Chevrolet/Geo Metro

zaken1 · July 2009

Incidentally, I'm not familiar with the G10 model number you often mention. My engine is referred to as a VIN code 6; and that designation is used on all the 3 cylinder Metros (both Geo and Chevy). The TPS on my 1990 5 speed is marked 179950-6281. It also is marked 1.5--6.0 degrees. And I expect it will work with your ISC motor.

They also used a different MAP sensor in the 1989-91 3 cyl models; which I find runs a bit richer (which I think would be a benefit in your situation). It has a thick plastic section where the mounting bolt goes through; while the later unit uses a metal plate in that location. It will mate with your harness plug. If someone installed the wrong MAP sensor, or if your engine's compression has now changed enough to have leaned out the mixture; the earlier MAP sensor would be worth trying. Mine is labeled 18590--60B00, and underneath that is another line reading 079800--1540.

shaggyman1 · July 2009

G10 refers to the ID number on engines of Suzuki manufacture, "G" being the engine type and "10" being the displacement, ie: G10 is the three cylinder 1.0L and G13 is the four 1.3L. 3rd digit is the model year, starting with "F" in 1985 and going to "Y" in 2000. The G series engines share many components, such as pistons, rings, bearings, etc.
VIN code 6 refers to the fuel system (8th digit in your VIN), 6 being Throttle Body Fuel Injection- so a G10 with TFI.
All of my TPS units appear to have only one switch (idle), rather than two, (the other being for WOT) but from what I've gleaned so far there is a third type with a continuous variable resistor as used on the 1.3 with port injection.
I'll check on the MAP- I think mine is plastic, but I'm not sure.

annielulu · July 2009

Zaken1:

I'm still fooling around with the car. I have checked EVERYTHING I could possibly think of and have hopefully narrowed it down to the COIL. I have been to auto parts stores here in Las Vegas. No one really seems to know what the correct coil should be. I bought one, but it was not the right one. Could you please tell me the correct coil manufacturer and part number. I checked the Rock Auto parts site, but I am still confused.

Thanks very much.

zaken1 · July 2009

Hi again,

The coil specification is not nearly as critical or restricted as your message implies. Virtually ANY 12 volt coil that has a 1.0-1.2 ohm primary, and is intended for electronic ignition applications will work on your car. I have used literally dozens of different types of coils on Metros; which work just fine.

In the Rock auto site; both the Airtex # 5C1069 or the AC Delco # E536 would be suitable. Basically, any coil listed for US model 1993 Metro LSI convertibles will work. And these coils will all look like a tin can, with the high voltage terminal and the two primary terminals together on the same end. The only listings which are not suitable are the ones for the Canadian models or the non convertible US models. And that difference will be very obvious; because the unsuitable coils will be more oval than cylindrical, will have an external metal core surrounding the coil, and will have the high voltage terminal on the opposite end of the coil from the primary terminals; with the primary terminals located inside a plug that will not match with your harness wires.

Now, there are other types of tin can style coils which are not suitable for the Metro; but they would not be listed as replacements for that vehicle. I believe that you already replaced the coil with a new one some time ago. If you think the parts clerk sold you a coil that was not intended for the Metro, and you can post all the numbers and markings, and brand information printed on the coil; I'll probably be able to confirm whether or not it is suitable.

I understand that you have checked everything you could possibly think of; but you must bear in mind that you are dealing with electronic parts here, which cannot be checked without meters and test equipment. Because you do not have this equipment, there are many items in the electrical system that you are not able to check. And it is certainly among those items where the problem lies. Electricity may not be visible; but problems with this invisible force still can prevent the car from running, even when the parts physically look just great.

Did the EVERYTHING that you have checked include the distributor pick up coil, and the ignition module, and what about the test I suggested for bypassing the ignition switch??? Pardon my skepticism; but since you are not skilled in this area, I would at least need to know the details of what you did, explained as completely as possible, in order to confirm in my own mind that each of these items is not the source of the problem. My experience has been that people all too frequently test an electronic component by performing some sort of rudimentary electical test that is either inappropriate, inconclusive, or is improperly applied; and then become totally confident that they have eliminated that part as the source of the problem.

And that is why I am requesting full and complete disclosure.

artcarclaire · August 2009

Hello, I have a 93 geo metro; last week, the water temp was reading normal until I gave it some gas. The water temp guage redlined and I took my foot off the gas, water temp drops back to normal. Luckily only a block from home; it does the same thing in reverse. Have repalced the thermostat, check all the fuses, flushed the radiator and have good even flow. I'm thinking now it must be elecrtical, but I'm not sure if I need to relace the coolant temp sensor, or the temp switch or what I should do. Thanks for any help!

senormechanico · August 2009

I'd suspect insufficient water pump delivery to the radiator for whatever reason.
Are you sure you have good flow through the whole system?
How fast does the temp change? If its only a few seconds, I'd suspect a bad electrical ground connection somewhere.

Steve B.

zaken1 · August 2009

Four possibilities come to mind here: 1> The radiator may not have been filled all the way to the top; or it may have initially been filled; but the level dropped when the trapped air in the system came out, and the level was not subsequently rechecked directly at the radiator. So, because the radiator is not full, there is now no siphon action between the radiator and the reservoir; so the radiator cannot refill itself from the reservoir, which makes the motor overheat whenever any additional heat input is added, because there is now an insufficient amount of coolant in the radiator.

2> The cooling system is filled with 100% pure coolant; instead of the 50-50 mixture of coolant and distilled water which it is designed to use. Pure undiluted coolant cannot transfer heat well, and thus must have water mixed with it, in order for it to be able to transfer the amount of heat which the engine generates when it accelerates.

3>The electric radiator fan has stopped working; which leaves the engine on the verge of overheating whenever you accelerate. You should be able to hear and see the fan run whenever the temperature gauge goes above about 3/4 of the way up. If the fan does not run when the engine gets that hot, the cooling fan relay has probably failed. That relay is located on the front edge of the underhood fuse box; near the fender on the drivers side, between the battery and the shock tower.

4> The head gasket has been damaged by the engine previously overheating; and now leaks hot combustion gases into the cooling system whenever the engine accelerates. This can be confirmed or disproved by connecting a cooling system pressure tester to the radiator neck, and watching the pressure gauge when the engine is accelerated. If the pressure in the cooling system increases significantly under acceleration; the head gasket is probably leaking. There is also another test for a blown head gasket; which involves drawing air from inside the radiator up through a vial containing a chemical which changes color in the presence of combustion gases. And an infra red emissions analyzer can also identify a leaking head gasket; by detecting hydrocarbons in the air inside the radiator.

If the head gasket is leaking; the cylinder head will have to be removed, and the head surface checked for warpage and the entire head checked for cracks. The head will often require remachining to make the sealing surface flat again. And if the motor has over 50,000 miles on it; the valves probably should also be reground. If a head gasket is replaced on an engine which has a warped head; the new gasket will leak, and the engine will continue to overheat.

zaken1 · August 2009

Hi again,

I'm sorry it sometimes takes so long for me to get new insights; but that's just the way my mind works these days.

There is another test you can do for free, which will determine whether the distributor pick up coil is the source of your problem (and I do believe that is the most likely issue at this time): Try push starting the car in second gear; by either having at least three healthy people push it by hand as fast as they can on a level or downhill slope, and engaging the clutch when the car is going at their maximum speed; or pushing it with another car, with a tire wedged as a cushion between the bumper of the push car and yours. Make sure the key is turned to the position where the dashboard warning lights are lit while you do. If the car starts, and does not subsequently restart with the starter; the distributor pick up coil is definitely bad. If you have not done the ignition switch bypass test through the cigarette lighter plug, as I previously explained; the start contacts in the ignition switch may be an alternate source of the problem. But if you did test the ignition switch by the method I suggested, and the car did not start at that time; then the distributor pick up coil is the only remaining possibility. I hope this helps!!! Joel

artcarclaire · August 2009

Hi Steve,
I am guessing that there is good flow; what I meant by that was, after a flush, the upper and lower hoses and the radiator were all heating up together, no cold spots in the radiator. The temp gauge will redline within a few seconds of applying gas, but it will drop to normal level just a quick after I let off the gas. Also, this doesn't happen when I rev the engine in neutral, only in gear. In neutral, the temp guage doesn't jump.
Based off the post with suggestions after yours:
It does not seem that the radiator is pulling from the reservior. I ran the car with the radiator cap off to get out the air; it is air free (from what I can tell) and still not pulling from the reservior. The fan is not kicking on, but I'm not getting the gauge over 1/2 just letting it idle, or reving the engine. The radiator fluid is mixed 50/50, I double checked that today.
I'm hoping that helps, looking forward to any other suggestions.

annielulu · August 2009

Zaken 1:

OK, finally found the problem. Underneath the fuel injector there is a little O ring that the injector sits on. Well, that stupid little ring was split from wear, so that the fuel supply was getting messed up.

When the ring was replaced, the fuel got straightened out-we were able to put the fuel fuse in again and it started.

However, I think that raw gas was slowly seeping into the pan after running down the cylinder walls slowly over a period of time. This resulted in a thinning of the oil so consequently I now have a rod bearing knock, but the car starts and runs ok now.

From what I can ascertain, we can install 3 new rod bearings pretty simply by dropping the pan to install them. There doesn't appear to be anything major in the way to access the bearings.

I wish to thank you very much for all of the help you offered. You put a lot of time into your suggestions, and I truly appreciate your help.

zaken1 · August 2009

Hi,

I'm delighted to hear that you found the problem!!! I would just like to suggest that I doubt the rod bearings were damaged by the diluted oil. So I believe that if you change the oil and filter, and then drive it a little, the knock should go away. A knock could also be caused if the ignition timing has been changed to an incorrect setting.

annielulu · August 2009

Well, I changed the oil and filter, 20W-50 grade oil, plus put in 16 oz or so of something called "Lucas Oil Stabilizer" and drove it around the block for about 5-10 minutes, but the knock was still there, it seemed to abate somewhat, and it gets quieter when accelerating and louder when just idling. Do you think it might get better over time? Not only that, but I now need a new starter or solenoid combo, as after all the trying to start it, the solenoid is acting up. I had to push it and pop the clutch to get it going. I wonder if I take off the starter, if somehow i can fix the solenoid. If I have to put in the rod bearings, I will. I do like the Metro, and when it does perform right, it is a great little car.

zaken1 · August 2009

All the rod knocks I have ever heard become louder under acceleration and load, and get quieter at idle. So this doesn't sound like a rod knock to me. The three possibilities I would entertain are 1> a hydraulic valve lifter which has an air pocket in it; which will eventually stop making noise after being driven at say 40 mph for a few miles, or 2> a timing belt tensioner pulley which is loose, worn or has been improperly adjusted, or 3> valve noise from carbon deposit build up on intake valve stems; which can be addressed by adding the contents of a small size bottle of Chevron Techroline fuel system and combustion chamber cleaner (which comes in small and large size bottles) to a tank of fuel just before filling it up. This particular product works much better than other brands; so it is well worth going to the trouble of getting it (at Chevron gas stations, Wal Mart, and Kragen, Checker, Shucks, Murray, and O'Reilly auto parts stores) It sometimes takes 50 or 75 miles of driving for the effect to become apparent.

You can often distinguish between timing belt tensioner and valve train noises by holding your ear against the end of a broomstick, stethoscope or a wooden rod, while touching the other end to various parts of the engine, and listening carefully to hear where the noise is loudest. Timing belt tensioner noises would be most pronounced when touching the middle of the timing belt cover. Valve train noises would be loudest at the valve cover or the side of the cylinder head between the spark plugs (and this is where a non metallic rod is essential for safety).

If the starter solenoid is defective, it cannot be fixed, but can be replaced. I hate to admit it; but I have forgotten whether this starter has a built in or a removable solenoid. I think it is integrated into the starter. Here again, perhaps it is not in the starter itself; but may be something as simple as a poor ground connection for a battery cable, corroded or loose battery cable clamps, or a loose wire from the ignition switch at the starter. It also might be a defective ignition switch or clutch pedal switch; so don't assume it is in the starter without proving it by trying to activate the starter with a jumper wire from the battery positive terminal to the tab on the starter where the wire from the ignition switch normally connects.

annielulu · August 2009

Zaken1:

I got lucky. A local salvage yard had a used starter on the shelf which I got for $35.00. I put it in and it works great.

The car starts right up now and runs great EXCEPT....... that knocking noise is definitely a rod bearing issue. My plan is to drop the pan and install 3 new rod bearings. There is hardly anything in the way, so access should be easy. Here is my question please: the car has 120,000 miles on it. Do you know what bearings I should get. Would you know the part number, etc.

Thanks so much for your kind assistance and help.

zaken1 · August 2009

Well, I will give you the information you asked; but I will not take any responsibility for the outcome, because;

1> it does not make any sense to me that fuel dilution during a long period of cranking or local driving will take out rod bearings. This is because gasoline has some lubricating properties, and the loads and speeds which the engine was subjected to during the time when the injector was leaking were very low. So I just don't believe that this treatment would be anywhere near severe enough to take out the bearings. I have seen many engines run on diluted oil, and I have NEVER seen bearings become damaged as a result. It is only when an engine runs out of oil that this happens.

2> Furthermore (and perhaps even more significantly) any combination of load and lack of lubrication which would be sufficient to take out the bearings would probably also score the crank journals. So if your bearings are really wiped out; you probably need to have the crank reground, in order to keep from repeating the same scene. If you insist on replacing the bearings; please inspect the crank journals for scoring or bluing before you install new bearings. If the crank is scored or discolored from heat; then you'll need to have the crank remachined, in order for the new bearings to last anywhere near a normal length of time.

3> The knocking created by loose rod bearings is directly proportional to the amount of load on the motor. It is quietest at idle, and becomes louder the harder you accelerate. But you said that your engine's noise is loudest at idle; and becomes quieter as you accelerate. And this is just NOT what bad bearings sound like.

4> There is another type of knock which sounds totally ominous, and which DOES sound like what you described. It once convinced me that a 3 month old Toyota Celica had something major broken inside its motor. This noise was loudest at idle. It sounded to me like a heavy metal bar was banging around inside the motor. When I first heard it on my client's nearly new Celica, I told her to not drive the car one block more; and to have it towed to the dealership for warranty repair of an obviously defective motor. And she did so. Some time later, I encountered her again, and asked her what the problem turned out to be with her car. And she told me that the dealership had just run some carbon solvent through the combustion chambers, and that had completely cleared up the noise!!! They then told her that the noise, which is referred to as a "carbon knock," was caused by her use of cheap fuel that had insufficient quantities of engine cleaning additives in it. And that had led to the build up of carbon in the combustion chambers to such a degree that it effectively increased the compression ratio to the point where the engine went into uncontrolled detonation at idle. The dealership then told her to NEVER use any fuel except Chevron (which contains adequate quantities of carbon solvents). And the problem never came back.

Some years before that, I had the same experience with a Honda motorcycle which I had bought new and lovingly maintained for 80,000 miles (except for always using cheap fuel). And I naively misdiagnosed that sound as a broken piston skirt; and as a result literally gave the machine away. I later learned that the person who bought it never did anything to the motor, and it gave him no problems afterward. Carbon knock is something that we old timers never encountered in the past. It is a unique consequence of a glitch in the chemistry of modern reformulated fuels; in which the additives which are used to replace lead turned out to produce heavy carbon deposits in combustion chambers. Some fuel manufacturers (Chevron, Shell, and Texaco) have developed additives which counteract this carbon build up. But those additives are expensive; so the cheaper fuels don't contain them. And that's where the carbon knock comes from.

But it's your car, and your life. You can do what you want with it. Since I've been down that road before, I am just trying to save you a bunch of time, money, and frustration. But you can override my advice, (at your own risk) if you want.

If you log on to Rock Auto's website, and select your car and engine model; scroll down to the "engine" category, click on "connecting rod bearing" and you can use any of the brands listed there. I personally would not use the Clevite/Perfect Circle bearing, because it is made of aluminum; which has poorer anti friction properties than the other brands. But the caveat in selecting bearing sizes is that some engines are manufactured with undersize crankshaft journals (as a result of a machining error when the crank was first manufactured). So those cranks would require a thicker bearing to achieve the proper clearances. Some connecting rods are remachined to a larger ID during overhaul, which also would require a thicker bearing.

The situation is compounded because some manufacturers (namely Beck Arnley) call thicker bearings "oversize" (which is literally what they are); while all the other listed manufacturers call thicker bearings "undersize" (because they are made to match an undersize crankshaft). This is just a difference in semantics. All bearings which differ from stock dimensions are thicker bearings. Nobody makes a bearing which is thinner than the stock part; regardless of what they call it.

But, since some new crankshafts have undersize journals, and some used engines have had their crankshaft remachined during an overhaul; you cannot assume any crankshaft has stock diameter journals. The journals must be accurately measured with a micrometer or dial caliper before you can know what size bearing will fit properly. Wear on the journal is not an issue in bearing selection (unless you have a Model T Ford). The journal will either be stock, or smaller than stock in .010"; 020"; or .030" increments. And the connecting rod inside diameter will either be stock; or larger than stock in .010"; or 020" increments.

If your crank journals are stock diameter, while the con rod ID is .010" larger than stock; then you'd need a .010" thicker bearing. If the crank journals are .010" smaller than stock, and the con rod ID is stock; then you'd also need a .010" thicker bearing.

Rod bearings for the Metro are made in stock thickness, and in steps of .010" (.25mm); .020 (.50mm); and .030" (.75mm) thicker than stock.

If you look at the part image for the Sealed Power # 31140RA bearing, there is a handy chart which lists the stock crank journal diameter as 1.6530-1.6535". This chart also lists the ID of the stock con rod as 1.7716-1.7721". Wear on journals is less than .001-.002" so it is not a factor in bearing selection. And the oil clearance is also not pertinent to this operation. Just measure the crank journal and rod ID, compare the numbers to stock; and you'll know what size bearing to buy.

vanillalatte · August 2009

WOW....
Thanks a million for taking all this time.
It started my day with a bang!

zaken1 · August 2009

Well, I just hope the impact did not damage your grille.

jessegeo · August 2009

i have a 1992 geo metro and it is leaking oil on the left side of the engine right below the valve cover, however i have replaced the valve cover gasket twice each time expecting the oil leak to stop and it hasnt , i used Permatex High Temp Red RTV Silicone gasket sealer along with a new gasket when i replaced the old ones, when the engine runs i can see the flow of oil leaking town the engine, im stumped and i dont know what could be causing the leak, any ideas??? thanks

zaken1 · August 2009

I assume 'on the left side of the engine' means the side next to the distributor. That end of the valve cover has a deep recess which fits over the flange on the head. If you are getting a severe leak at that location; it could come from a crack or gouge in the valve cover or head; or from debris on the valve cover or head surface which keeps the valve cover from seating fully; or from the use of a cork or fiber gasket (the original equipment gasket is rubber); or from uneven or insufficient tightening of the valve cover nuts; or from the use of plain nuts instead of the original cap nuts to hold the valve cover on.

It is absolutely essential that both the head and the valve cover be surgically clean and free of all traces of old gasket material and sealer along the entire sealing surface, before installing a new gasket. This cleaning should include the recesses in the curved part of the valve cover. You can use an inspection light and a screwdriver, solvent, an Exacto knife, dental probes, or similar tools to reach into the corners of the cover and remove fragments. It just takes one tiny chunk of debris to keep the valve cover from seating completely. And after the parts are cleaned; thoroughly check the entire sealing surface for cracks or gouges.

The gray formula Permatex RTV is preferable to the high temp red formula; because it is more resistant to being squeezed out of place when the cover is tightened. And that cover does not get hot enough to require high temperature sealer. It is also important to only apply only a thin, even coat of the sealer to the top and bottom faces of the gasket (not to the metal parts); and then wait about ten minutes after applying the sealer to allow it to set up, before installing the gasket in the valve cover. The sealer should still be tacky enough to hold the gasket in the cover without it drooping out of position. And the valve cover nuts should be tightened in a criss cross pattern, going back and forth in several steps between nuts on opposite ends; so the cover can come down evenly. The final tightening should be done with a torque wrench, to 15 foot lbs.

Some brands of gaskets may be made of cork, fiber or cardboard. These are inferior quality, and should not be used on this motor. If that is the type of gasket you've been using; find a store that sells a rubber gasket. And be sure they sell you the right gasket for this motor. It should match the shape of the cover, and fit snugly in the cover without needing to be cut or shortened. Also note that there is only one way the gasket will fit; there should be one curved end that matches the curve of the valve cover and the cylinder head. And the gasket definitely has a top and a bottom side.

Some gaskets also come with grommets. These grommets go on top of the valve cover, under the cap nuts. If your gasket came with grommets, and they were placed underneath the cover; they would prevent the cover from seating.

carol54 · August 2009

I don't know if this helps but I just had a bunch of work done on my 99. They said that leak on the left side was coming from a seal that has to do with the timing chain component. They said if they went in there to replace it, it would be a kind-of a major deal, so it would be kind-of expensive, that it probably would be okay for a while if I am not going thru too much oil.(I usually have to add about a quarter of a quart a month). I didn't get it fixed this time, as I spent $475 ona new pressure plate, something to do with the clutch and about 5 bolts were missing from my tranny! Whoever owned the car before replaced the original engine with another type and I didn't have a clue. I am misssing a couple of motor mounts and a tranny mount.A couple of these the auto shop could not find anywhere and they think it is because of the motor change. So I'll just bip-bop along and when it starts to rattle too much or the gears start jamming at first notice I'll take it back to the shop to have him tighten it all up again.

shaggyman1 · August 2009

1996 1.0 5 spd
Been on this one for months- starts fine but can't give any throttle before it warms up, or it floods out.
Checked the voltage at the Coolant Temperature Sensor by backprobing.
It has three wires:
Light Green/Black, which is common and goes to the MAP, TPS, and IAT. Gray/White, which is the signal to the ECM.
Yellow/White, which is not shown on wiring diagram, but I assume is the input from the ECM.
LtGr/Bk is ground- no voltage.
Gy/Wt reads 2.34V when cold, decreases with rising engine temp and finally goes to 0.5V when hot, at which point the cooling fan kicks on and takes it back up to around 0.65V. (With two different CTS units- same within .2V)
At anything over 1.0V, the engine will flood and stall if the throttle is opened even slightly.
These values seem reasonable if the temperature was around zero- but it's 80.
What does not seem reasonable is the voltage on the Yellow/White wire which I believe should be the standard 5V input from the ECM, but reads a steady 9.2V, regardless of temperature and even when not running with the ignition on. If the input voltage is nearly twice what it should be, then the CTS could have exactly the correct impedence, but the output signal would be much higher than the ECM expects, and it would compensate with a mixture richer than Bill Gates.
Is it possible that something is creating a field that the wire is having additional current induced in it somehow? My DMM read nearly a volt with the positive probe held in the air near (2 inches) the sensor wires.
I hope this is the gremlin I have been looking for since April, but I don't have a clue how it could get 9.2V.
Maybe something a little over 12v, yes- but not 9.
Anyone see this before?
Hints? My crystal ball keeps saying to try again later....

zaken1 · August 2009

Hi there: Since the amount of change you see in the CTS is in a range which seems reasonable; and the CTS ground is common with the TPS, IAT, and MAP; it would seem likely that the problem may be in one or more of those other devices; and not in the CTS. Also, I would not pay too much attention to the voltage reading you get on the Yellow/White wire; as the no load reading from a power source, when measured with a high impedance meter, may be greatly different from the voltage the computer 'sees' from that source. This is because your meter is grounded to the engine; which is electrically connected in common with the alternator, battery, and ignition system. The 5 volt signal from the computer, however, is a closed loop which is isolated from those other components. As an example, I have a plug in power supply for a phone answering machine; which has a rated output of 9 volts DC. But when I measure the open circuit output voltage from that power supply with my DMM; it reads something like 13 volts!!! However; as soon as it is connected to the designed load; that voltage drops to 9 volts. Because of this; plus all the inductive input and transients the meter will pick up; I would only become concerned about the supply voltage if you read more than 5 volts across a given sensor; rather than measuring voltage between one side of the sensor and an engine ground.

But there is one other factor here which proves this point: The CTS resistance is highest when it is cold, and drops as the engine warms up. This means that the voltage signal the computer "sees" from the sensor is LOWEST when the engine is cold; and becomes higher as the engine warms up. So if your supply voltage was too high, the computer would get a signal that the engine was hotter than it really is. And under that condition, the engine would not go rich when throttle was applied. Instead, it would go too lean. But you claim the engine is flooding.

Actually, I believe you are confusing the behavior of a flooding engine with one that is going too lean and starving for fuel. An engine which is too rich is typically insensitive to small changes in throttle opening; and will easily accept sudden openings in throttle position. A rich engine will also run much better when it is cold than it does when it is warmed up.

On the other hand; an engine which is too lean will stall out if the throttle is opened when cold; but will run much better after the engine temperature comes up to normal. So I believe this is what your engine has been doing. Hopefully this will give you a better sense of where to look for the source of the problem.

Here's a simple test you can do to prove this: Disconnect the plug to the IAT sensor, and then try running the motor. I bet you'll find that the cold stalling is gone. The IAT sensor is just like the CTS. Its resistance is highest when the air temperature is cold. So when you disconnect the IAT plug; the computer thinks the air temperature is below zero; and richens up the mixture.

zaken1 · August 2009

One other thing could also be going on here; if you don't see the oil actually coming from the valve cover, but can see it running down the engine below the distributor; chances are the oil is coming from the distributor housing rather than the valve cover. There is an o-ring on the distributor body which can become damaged or disintegrate over time, and a torn gasket between the distributor mounting flange and the cylinder head can also cause an oil leak.

shaggyman1 · August 2009

Uh oh.
The voltage most definately decreases with increasing temperature, which means the resistance is increasing. WTF? How could both my sensors work backwards?

And the fan comes on when the voltage hits half a volt- shouldn't it be coming on with some increased voltage? If I disconnect the CTS the fan comes on, which implies that a zero volts signal received triggers the fan circuit.

Tried disconnecting the IAT- no change.
(It is receiving an index of 4.95V from the ECM)

Tried measuring the voltages accross the signal and common ground wires, rather than grounding to the battery- same.
It read 2.65V after sitting all night, and decreased as the engine warmed to a minimum of 0.50V, at which point the cooling fan came on. Maybe I drew the wrong conclusion from results, in that the signal of 0.5V is interpreted as zero, the same as if the sensor was disconnected, and the ECM thinks it's a malfunctioning sensor and defaults to cooling fan ON?

I'll go and get another sensor today and see what it does. I could swear that when I tested the impedence on that unit it decreased with heat.
I am disturbed that the wiring diagrams only show two wires, rather than the three I have. It implies other info may not be precise, either.

Anyone with an FSM for 1996 have a table of voltages through a temperature range?

My head hurts. Feels like I am dealing with things that violate accepted laws of physics- which implies I may be wigging out in a rather interesting fashion....

zaken1 · August 2009

I have seen temperature/resistance charts for those sensors; which are in the FSM. And they show a resistance of many thousand ohms (perhaps 5,000 to 15,000 or more) when the sensor is cold; decreasing to a few hundred when the sensor is hot. This is true for both the CTS and the IAT sensor.

In view of this; it sounds to me like you are interpreting the voltage drop ACROSS the sensor as the amount of signal the computer sees. But this is just the opposite of what is happening. The higher the resistance of the sensor is at any time; the more the voltage will be dropped across the sensor. And the more voltage that is dropped across the sensor; the lower the voltage will be that reaches the computer.

Think of it this way: If there is a 5.0 volt supply to a sensor circuit, and the sensor has enough resistance to drop 3.5 volts across it; the computer will only see the remaining 1.5 volts. IT WILL NOT SEE THE 3.5 VOLTS YOU ARE MEASURING ACROSS THE SENSOR. Similarly, the lower the voltage drop there is across a sensor; the higher the signal voltage will be at the computer. We know this much; sensor resistance decreases with heat; which will produce less voltage drop across the sensor. So if you are measuring lower voltage at the sensor as the engine warms up; you must be measuring the voltage ACROSS the sensor; rather than the voltage in series with the sensor. And that is the source of your headache.

Furthermore, I believe the engine temperature sensing circuit is connected in SERIES through the CTS and IAT; rather than in parallel. I also believe the engine load sensing circuit is also connected in series through the TPS and MAP. And this would further confound your attempts to measure the circuit dynamics.

But I see one thing that is not right in what you measured: Disconnecting the IAT should NOT have resulted in no change. If it did; this indicates either a short across the IAT sensor, or else the computer was not responding to the change in IAT signal, because it was in "limp in" mode as the result of a trouble code having been set. Does your "check engine" light come on when you first turn the key on, and does it then go out after the motor is started? If it doesn't come on at all; or if it stays on all the time; then the computer is in limp in mode, and will not respond normally to sensor inputs. In this case, you'll need to clear the trouble codes with a code scanner (assuming your 1996 model has an OBD II engine control system) Trouble codes can only be cleared by disconnecting the battery if you have the earlier OBD 1 system. And you can't tune the motor when it has a trouble code set in the computer. I know scanners are expensive; but there is no easy way around this. Actually, some people say that turning the ignition key on and off about 15 times in succession will clear OBD II trouble codes.

shaggyman1 · August 2009

Pulled the CTS and put it in the freezer- resistance at 0 degrees F was around 8000 Ohms. Put it in hot water and watched it fall to233 Ohms at 212 degrees F. So it is working properly. It could be the thermister is betwwen the signal to the ECM and ground, which would make the voltage decrease with the resistance, but I would be seeing the opposite.
Fine. At last some logic in the chaos.
In looking at the wiring diagram i see the O2, MAP, IAT, TPS are all in fact connected to the CTS.
So how is one to correctly troubleshoot these components? AAAARRRGGGHH.
Removing the IAT had no effect because (as you pointed out) it had set a fail code when I disconnected the CTS, and was in limp mode.
(BTW) I've found that an easy way to clear the codes is to first disconnect the negative battery cable, then ground the positive cable to the chassis for a few seconds, thus draining the various capacitors- including those pesky ones in the airbag system. Beats a trip to O'Reilly to borrow their OBDII reader.
(Personally, I think they should be built in with readouts available in real time)
Back at it tomorrow, with a new TPS which seems to have a much better and smoother resistance curve than the last two. Got my fingers crossed. Again.
Thanks Zaken! I thought I was witnessing a miracle gone horribly wrong....

zaken1 · August 2009

FYI; the only way to conclusively test sensors is to pull them and test them individually, as you did with the CTS.

Now, back to today's problem; if I were working on a vehicle that acted the way you describe, I would begin with the simple and direct approach: The symptoms you described sound just like what happens whan a TPS is adjusted too lean (set too far counterclockwise). So, before doing anything else, I would loosen the two mounting screws; and turn the damn thing clockwise until there was a noticeable improvement in the running. Forget the adustment specs; those specs are only valid when the engine is all new and stock. As soon as the compression changes, or any of 1,000 other factors changes; the TPS setting goes off. I have had to reset mine all over the range, after changing other things on the motor. And it ran great in all sorts of different settings, when they were appropriate.

It would only be if resetting the TPS as far as possible did not correct the problem, that I would start thinking about defective sensors or other exotic issues.

If you set the TPS too rich; the consequence will be that the fuel cut does not come in during decelleration. And that is fairly obvious, as you slow to a stop in gear. Normally, the fuel should come back on as you get down below about 10 mph; and the car will feel different when that happens. But the other consequence of too rich a TPS setting is that the fuel mileage drops severely; and the exhaust pipe becomes wet and sooty.

One owner wrote in here some time ago; complaining that his exhaust pipe always looked rich. So I finally helped him to overcome his fears about disturbing the TPS setting; and explained that it has to be done by the "seat of the pants." A few weeks later, he wrote in to thank me for going against what everybody else had said, and reported that it took a series of tries and road tests before he finally got it right; but his car now is peppier than ever, the pipe is brown and clean, and the fuel economy is great.

shaggyman1 · August 2009

TPS settings don't have any effect on the stalling problem- only warming the engine will allow it to run.
I connected a known good CTS and immersed it in boiling water, thinking to imitate a warm engine and started it. Died as soon as I opened the throttle. So the coolant temerature sensor or it's circuit is not the culprit.

Okay, what else is temperature sensitive?
What about the Early Fuel Evap Heater (EFE) in the plate under the Throttle Body?
Fuel system component, temperature related, has a 30A fuse and a relay.....
It's on the car, in the wiring digram, and utterly without mention in Chilton or Haynes. AllData says it preheats the Fuel/Air and reduces the time in open loop, until engine reaches operating temperature when it is deenergized by the ECM.
Resistance should be 0.5 to 3.0 Ohms. (seems low for a heater) Checks at 2.6 Ohms across the leads, and open from either lead to battery ground.
Connect unit and measure voltage: Voltage coming in while running is 13.4V with a drop to 1.2V on the ground side. (12V drop) Tht's a heckuva drop for 3 Ohms. Sounds reasonable that it might be the culprit.

zaken1 · August 2009

Well; it sounds like the time for a little more education: The supply voltage in any series electrical circuit will ALL be dropped across the sum total of the resistances of the loads in that circuit; regardless of how much or how little resistance there is in the circuit. The amount of voltage drop across any single element will be proportional to the percentage of the total circuit resistance which it constitutes. Regardless of whether there is one, or six, or one hundred resistive elements in a 12 volt circuit; the entire 12 volts will always be dropped across the whole circuit. Suppose there are six resistive elements in a particular series circuit. If each of those six loads have the same amount of resistance; then each element will drop 1/6 of the total circuit supply voltage (which works out to 2 volts drop across each element). If there is only one resistive element in the circuit; then the entire 12 volt supply voltage will be dropped across that one element (regardless of whether the resistance of that element is 1/10 ohm, 5 ohms, or 10,000 ohms). If there are unequal resistances in a series circuit; then the supply voltage will be dropped across those loads in proportion to their resistances: Suppose there is a 5 ohm and a 10 ohm load in series with a 12 volt supply. In this circuit, the total circuit resistance is 15 ohms. The 5 ohm load makes up 1/3 of the 15 ohm total circuit resistance; so it will drop 1/3 of the supply voltage (which works out to 4 volts). The 10 ohm load makes up 2/3 of the 15 ohm total circuit resistance; so it will drop 2/3 of the supply voltage (which works out to 8 volts). 4 volts + 8 volts = 12 volts; which makes this a legally functioning circuit, because the entire supply voltage is used up.

I hope you can see from this that the voltage drop across a 3 ohm load has NOTHING to do with the amount of resistance of that load. It is solely determined by how much ADDITIONAL resistance is in series in that circuit. If the 3 ohm heater is the only resistance in that circuit (which is what I would expect in a heating circuit) then the entire 12 volt supply (minus what is dropped across the plugs and wiring harness) will be dropped across that 3 ohm resistance. Applying Ohm's Law (Current = Voltage divided by Resistance); 12 volts / 3 ohms = 4 amps. 4 amps current at 12 volts is 48 watts of power (Power = Voltage X Current). 48 watts of power is about what a single 12 volt headlight draws. That is not at all unreasonable for a heater that has to bring a steady stream of fuel and air up to a temperature high enough to vaporize the fuel. It probably sounds high to you because most other current draws in automotive electronics are much smaller than that. But I expect the rear window defroster grid draws at least that much. And the starter motor draws 20 to 30 times that much!!! So your test of the EFE heater tells me that it is working right.

I appreciate your perception that this appears to be a temperature sensitive problem; but I assure you that the root cause will turn out not to be someting directly related to temperature, and will instead turn out to be related to excess leanness, or sudden changes in air/fuel ratio when the throttle is opened. I'm glad you tested the TPS and eliminated that as a potential cause. I can accept that; and this information helps narrow down the focus.

What it now sounds like to me is that the EGR valve is opening too soon, or too suddenly, when the throttle is opened. This would happen if one or more of the EGR vacuum control devices were bypassed or missing. (there should be an exhaust back pressure tradsducer and an electrical vacuum switching solenoid in the vacuum lines to the EGR valve). It would also happen if the ignition timing had been adjusted without first disabling the electronic advance by shorting the check connector wires.

zaken1 · August 2009

In addition to improper EGR valve regulation (the EGR valve essentially acts as a massive timed vacuum leak into the intake manifold), two other vacuum related issues would be a vacuum leak in the hose to the brake booster from the intake manifold, or the use of the wrong model PCV valve, or a PCV valve that was not plugged into its socket. An additional EGR issue could come from using manifold vacuum, or the wrong throttle body vacuum spigot, to supply the EGR circuit (it should come from the spigot on the front of the throttle body which is closest to the passenger side). A purge circuit issue could be caused by using manifold vacuum or the EGR spigot to supply the purge control valve (it should come from the port on the front of the throttle body which is closest to the driver's side).

You can eliminate the EGR valve as a factor by simply disconnecting and plugging its vacuum hose; and seeing if that changes the stalling behavior. However; the EGR valve may also be sticking partly open; and may thus never close fully. And that would continue whether the vacuum hose was connected or plugged. It should be possible to reach underneath the valve actuating diaphragm, and manually raise and release it to see whether the spring returns it all the way down. If you manually raise the valve while the motor is cold and idling; it should make it stall.

And if none of these things work, it is probably time to reset the dreaded idle air bypass.

shaggyman1 · September 2009

96 Metro 1.0/5spd
Check engine light flashing occasionally while driving. Flashes for a couple minutes, then reverts to steady on for a while, then starts flashing again.
Does this indicate it is busy setting a code? Is the brainbox freaking out?
I'm currently getting a fairly frequent #1 cylinder misfire code, but I've never seen the light flash while driving before.
Don't find any mention of this in forum archives or in manuals.

Currently have bad compression in #1, and am waiting on parts to arrive to do a ring and valve job. Hopefully I won't have to replace the ECU too.

zaken1 · September 2009

My check engine light has flashed on occasion; when the air/fuel mixture was too lean in one particular load range; but was OK at other loads. What you describe sounds pretty normal; particularly considering the low # 1 cyl compression. I would expect it to go away after the compression is fixed. I seriously doubt that there is a problem with the computer.

zaken1 · September 2009

I just wanted to add that when one of these motors reaches the point where it is leaking compression past the pistons; just replacing the rings is often not enough to fix it. The reason for this is that a major part of the leakage takes place from the ring gooves in the piston becoming enlarged by wear. And that leads to compression leakage on the inside edge of the rings, through the ring grooves. In addition, when the ring grooves become worn; the increased clearance erodes the support the grooves normally provide to the rings; which allows the rings to twist and flex. And that raises havoc with the seal between the rings and the cylinder wall. So the right way to fix the problem is to replace both the rings and pistons; once it has been determined that the cylinder bores are still straight enough to support new pistons.

These little motors make much more economy and power for their size than an old Ford flathead or Chevy 6; and as a result they are far more critical and demanding about precision in mechanical tolerances and tuning adjustments.

shaggyman1 · September 2009

96 1.0/5
Valve job, rings, bearings. Compression test shows 200 in all three.
Replaced: MAT, Distributor, Coil, Cap/rotor/wires/plugs, PCV and
Throttle body with TPS, Injector, Fuel Pressure Regulator, ISM.
Thoroughly clead all carbon from pistons and EGR tube in intake manifold.

Set a code for EGR flow after 40 miles- had the vacuum lines reversed on the modulator (the label on mine was gone). Just to be sure, I replaced all the vacuum lines, the modulator, and both the solenoid valves.

Runs great, except for two problems:
1. Cold starts are the same as on the last engine/TB, etc- will not accept ANY throttle without dying until warmed up. ( I now suspect either the TPS, which is a three wire without an idle switch in it) or the fuel vapor purge system, which I find difficult to fathom. I just don't want another burned valve in a couple thousand miles....

2. Air in the cooling system- this one REALLY scares me, as I don't seem to be able to clear it out. It will idle warm with an occasional bubble in the radiator filler neck, but when I race the engine, I get lots of bubbles, with an occasional surge- as if there were a pocket of steam forming somewhere and suddenly venting with the increased flow. The bubbles do not smell like exhaust, and there is no greasy film on top of the water (haven't put antifreeze in yet, as I don't want to waste it).
Could this be a failing water pump, or is it more likely to be a cracked block?

Is there a flow spec for the water pump? Some kind of sniffer for the cooling system?

zaken1 · September 2009

You say you replaced all those parts; but were they new or used replacements? If they were used; there might be compatability issues. And even if they were new, there still might have been errors in listings or model selection. There were significant changes in the TPS and distributor over the years. I tend to feel that you still don't have the right TPS. Also; the distributor for the 1996 model should not have a vacuum advance. If it is the right type (made for electronic advance, rather than vacuum advance) the timing MUST be set with a strobe while the check connector terminals are shorted to disable the electronic advance. Otherwise your timing will end up too far retarded.

Does your engine have an electrical EGR vacuum switching valve unit in series with the exhaust back pressure transducer? If the VSV is not in the circuit; the EGR valve will get far too much vacuum; which will create all sorts of undesirable leanness. Do you have a vacuum hose routing diagram, so you can be sure the hoses are correctly routed?

Regarding the evap cannister purge; the purge control valve on top of the cannister (at least on the earlier models) is activated by a vacuum signal from the purge port on the throttle body. There is some sort of temperature sensing "wax valve" plumbed into that vacuum line; which bleeds air into the signal line when the engine is cold, to reduce the strength of the vacuum signal to the purge control valve. If that air bleed function is defeated; it would result in the purge valve opening when the engine is cold; which would cause severe hesitation.

On the earlier throttle bodies; there are three vacuum spigots, coming from ports which are all located at slightly different heights. The spigot closest to the distributor is intended for the purge system. The port which supplies that spigot is the highest of the three on the throttle body wall; which means it will be the last one to supply vacuum as the throttle is opened. The spigot furthest from the distributor is used to supply the EGR vacuum signal. It is the lowest (earliest opening) of the three ports. And the spigot in the middle was used to supply vacuum to the distributor advance (on those cars with vacuum advances). That spigot is typically capped on cars with electronic spark advance. If you get vacuum from the wrong spigot; it can really mess up the engine operation, particularly with regard to setting EGR codes.

Have you tried setting the heater temperature valve control to maximum heat; in order to purge all trapped air from the heater core? And do you have a thermostat installed in the cooling system? Running without a thermostat can create weird imbalances in coolant flow. You can check for pressure build up in the cooling system with a radiator pressure tester. Install the tester in the filller neck, and pump up just enough pressure to lift the needle off the peg. Then start the engine while it is cold; and watch the pressure gauge. There should be no significant increase in pressure for at least the first 5 minutes of running (or until the temperature gauge reaches normal and the thermostat opens).

shaggyman1 · September 2009

Most of the RPL parts were used, but bench tested okay.
All of the TPS units (5) are the same- 3 wires, same as my harness.
Input Voltage from ECU, Signal to CPU, and ground. Signal always goes through the potentiometer.

Distributor is correct- with no vacuum advance and the pickiup coil bench tests okay.

EGR is a bit different: Vacuum from TB base goes to a VSV, which goes to the "P" side of the modulator. The "Q" side of the modulator goes to a second VSV, which controls actuating vacuum from another spigot on the TB, which is connected to the
EGR through this second VSV. All connections are true to the diagram on the hood.

The third and lowest spigot goes to the purge system. I think I will try plugging the line to the purge system and see what it does to a cold start.

I have a new thermostat which functions as expected, and have "burped the system from the high point on the back of the TB. Spot on with the pressure check- I hadn't thought about it in that way. If the engine is cold, there should be no increase in pressure until the coolant starts warming up, so an increase would have to come from combustion gasses leaking into it. I sure hope not- I really don't want to tear the whole thing down again. Sigh. At least I have a couple other blocks to start with, and might as well jump on whichever one has cylinders in better shape. (BTW, the piston ring grooves appeared to be undamaged, although I didn't bother to mike them- I was hoping for a quick 'n' dirty rehabilitation, not a perfect remanufacture)

Thanks for the good advice....

offshore3 · September 2009

I have a 1996 geo metro I am restoring and the vacuum hoses are missing. Its a 1.3 liter. Does anyone have a diagram of these hoses?
Thanks

leadfoot429 · October 2009

I have 95 metro 1.0 engine with manual 5 speed it starts and runs as long as i give it gas and drives normally. just replaced fuel regulator had head done a few weeks ago ran fine for a week then this O2sensor gave readings of .4- to 1.2 volts seams a little high since most i read say up to 1 volt TPS was smooth resistance from bottom of reading to top dont remember what the readings where exactly idle control motor is working after took it off and cleaned it and surrounding stuff. also the fuel milage has dropped 5-7 mpg since head gasket was done not so much worried about that as the wont idle (dies every time come to stop sign) since i drive 55 miles to work then same home kind of pain driving it this way i am new here so any help would be appreceated()

leadfoot429 · October 2009

sorry i ran everything togther-- still new to forums

zaken1 · October 2009

Sounds like you have a bad vacuum leak somewhere, or your vacuum hoses are not connected properly; or you have a fouled spark plug or bad plug wire or defective distributor cap; or the ignition timing has gone off; or have lost compression in one or more cylinders. Sorry I can't be more specific.

leadfoot429 · October 2009

vacuum leak not it sprayed carb cleaner around no change hoses are where they supposed to be .. spark plugs look good ... wires proper resistance... cap think would affect running ability? like i said runs well above idle just wont idle . help!!!

zaken1 · October 2009

Well; if we assume your observations, and the assumptions you drew from them are correct; then there isn't anything wrong with the car. And in that case, I flatly can't help you. And neither can anybody else.

But in my lifelong career as a diagnostic specialist, plus also having owned a Geo Metro for the last 17 years; I have repeatedly found that things are often not quite as clear as they seem to be. And all too often; people dismiss perfectly valid possibilities I suggest because they have not had enough experience to see how they can be so.

Since I don't know anything about your experience or abilities; I'll start by giving you the benefit of the doubt. So I'll not challenge that anything you claimed is not correct, just yet. Instead, I'll list those things which fit with your description; which could still be issues. The first one is compression: Just because the head was freshly redone doesn't mean that the cam timing has not slipped, or the belt tensioner is not too loose. So I'm respectfully asking you to run a compression check on the motor, at this time (even if you already ran one two days ago). I need to see the actual numbers; not just whether it "passed" or not. Low compression cylinders on a Japanese motor will often only have a noticeable effect on the idle.

The second possibility; if the ignition timing had been adjusted without having first disabled the electronic advance (by following the manufacturer's instructions about shorting the check connector terminals); the actual timing would come out way too retarded. And that would both screw up the fuel economy and the idle.

The third unmentioned possibility that fits within what you wrote is that the EGR valve is sticking partly open. This would create a massive vacuum leak at idle; which would go away when the throttle was opened beyond idle. So I suggest removing the EGR valve, and thoroughly cleaning the carbon out of it; and then working the diaphragm through its full travel by hand; to make sure it closes completely every time you let go of the diaphragm. Then confirm that the EGR valve is not receiving a vacuum signal at idle; by disconnecting and plugging the EGR vacuum hose, and seeing if this changes the idle behavior.

The fourth possibility is that the fuel injector is not closing completely, or the O-ring under the injector has deteriorated; and as a result, fuel from the injector is pouring into the motor when it should be spraying just a fine mist. And both a sticking EGR valve and a sticking or leaking injector would ruin the fuel economy.

The fifth possibility is that someone has disturbed the factory sealed throttle stop setting on the throttle body; and has set the stop too far closed. This would be compounded if the idle air bypass screw has also been closed too far. And that, too, would mess up both the economy and the idle.

Sixth; if the throttle position sensor adjustment had been set way too rich (too far clockwise); it would do the same thing.

But if you have run ALL of the above tests and none of the above points are valid here; then I would say that, even though the spark plugs look good to your eye, and you think that the distributor cap would not be the problem if the motor ran good above idle (by the way; my definition of "running bad" includes getting abnormally poor mileage, even when it 'seems' to be running well) please give ME the benefit of the doubt; and install a new set of Autolite # 63 spark plugs (NO NGK'S HERE, PLEASE) and a new NAPA distributor cap.

Thank you.

leadfoot429 · October 2009

well we found it- sorry if we insulted you but we are fairly knolageable just needed some help--and we Thank you for your help -- seams like the new head work may have created to much comprestion for the rings did compresstion test and had 65 in #1 , 35 in # 2 , and 50 in # 3 so any other advise--lol ya not good .. timing marks still lined up-- it wont even run now--just my luck ant one 95 geo with bad motor---lol

zaken1 · October 2009

If you don't mind my saying so; I don't believe that anything you could have done to the head would create so much compression that it would damage the rings. What sounds much more likely to me is that the low compression is being caused by the timing belt having slipped out of position. I understand that you say the timing marks are still lined up; but I've seen Metros where the belt slipped 180 degrees; so the timing marks still looked OK, while the cam was way out of time. The sure test for this is to turn the engine until the timing mark on the crank pulley lines up with the 6 degree BTDC mark on the scale on the timing cover. Then pull the distributor cap and look at the rotor position. The tip of the rotor should only be pointing either straight up, or straight down. If it points anywhere else; the cam timing is off. A confirmation of this test is that if you pull the spark plug in # 1 cylinder (the cylinder closest to the crank pulley) and insert a rod through the plug hole; if the rotor tip points straight up, the piston in # 1 cylinder should be at TDC. If the rotor tip points straight down; the piston in # 1 cylinder should be at bottom dead center. If the piston is anywhere else; the cam timing is off (or the distributor drive tang is not properly engaged with the camshaft).

One other thing that could cause the cam timing to be off, while the belt is tight and the marks appear to be lined up, would be if the woodruff key that locks the crank gear to the crankshaft has been sheared off; or was not in place when the timing belt was installed. I hope this is helpful.

vikasintl · October 2009

In 1996 Geo Metro 4 cyl. LSI 1.3 liter what could be cause for oil in air filter chamber and leak from there?
And once you tell us what could be cause what is the solution for that?
Car has 134K miles on it? does it indicate motor needs to be rebuilt?
Someone suggested to use sea foam and some one suggested to change PCV valve? Some one else said leaking head valves.
How much it should cost to fix this?

shaggyman1 · October 2009

Save your money on the SeaFoam- it will make it worse, and it is only kerosene with some detergent in it.
The oil is coming in to the air filter housing through your PCV valve, probably due to worn rings.
It is also possible that it is worn valve guides.
Or both. Not much to be done about either without a teardown.
If you are a competent mechanic, you might get by for under $200 in parts and valve job labor, depending on how bad things are. The sky is the limit on what you *can* spend....

papazcol · October 2009

Hello, hopefully somebody can help. I found an oil leak on the right corner of the oil pan (seeing from the drivers seat). The oil pan seal was replaced but the leak is still there, the thing is I cant see where exactly the leak comes from, oil filter is new and dry.The alternator belt is also new. I dont know if this has something to do with the leak but it came after I removed the AC compressors belt (the bearing was broken and replacing the compressor was about the price of the car itself). . I appreciate any comment.

zaken1 · October 2009

The most likely source of an oil leak in that area would be a bad front crankshaft oil seal. This is a seal on the end of the crankshaft, in the engine block behind the bottom (smaller) timing belt sprocket. The crank pulley, timing cover, timing belt, and lower sprocket would have to be removed to access that seal. If that seal was bad; it would spray oil all over the timing belt and the inside of the timing cover, which would lead to the belt degrading and eventually failing. It would also cause oil to leak out onto the fan belt pulley and the oil pan.

shaggyman1 · October 2009

1996 5/3
Good (180 all 3 tested today) compression.
Replaced:
Coil
Noise Suppressor
Injector
Injector Resistor
Plugs
Plug Wires
Pickup Coil
PCV
MAP sensor
TPS
MAT sensor

Timing is 10 BTC, firing order 1-3-2
Will not start, EXCEPT if I remove #1 spark plug wire- then it will start and idle on 2 cylinders. WTF?

papazcol · October 2009

Thanks Zanken, do you know if there is a way to diagnostic if the crankshaft seal is bad without removing all these pieces? should be a leak coming from inside the pulley? it's quite difficult to say right? Regards.

Chevrolet/Geo Metro

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