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Chevrolet/Geo Metro

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  • zaken1zaken1 Posts: 556
    Please note the date on a message before deciding to reply to it. The message you replied to here was written in November 1998; almost 14 years ago. Please also note that Geo Metros were not built with Chevrolet design technology. They were designed and built by Suzuki in Japan.
  • tvmogultvmogul Posts: 5
    Replaced OG crank shaft position sensor twice and still having issues re-accelerating after having to decelerate in traffic. Car actually shuts off but since its standard shift, I am able to restart while still moving.

    I am thinking main bearing may be loose (which I would rather not spend the $ to replace since the car has over 130,000 miles lol) so I am going to try thicker oil - 20w-50. (now using 5w-30)

    Any other ideas?
  • zaken1zaken1 Posts: 556
    edited March 2012
    Yeah; I have several other tried and tested ideas; but they largely go against your ideas. If you have enough trust to consider them; it will be to your benefit.

    1> Your '98 Metro is not a Geo Metro; it is a Chevy Metro. General Motors sold the Suzuki built Metro under the Geo brand from 1989 to 1997; but they changed the name of the car to Chevy Metro in 1998, and it remained a Chevy Metro from 1998 through 2001, when it was last sold. The 1.0 liter motor was last sold in 2000. The importance of this is that if a parts clerk looks under Geo for parts for a 1998 model; they won't find any listings.

    2> Like many other owners; you have mistaken the throttle body fuel injection unit on your car for a carb. Metros never had a carb. The fuel injection throttle body just looks like a carb; but if you take it apart; you'll find that there is no choke, no accelerator pump, no float, no jets, no power valve, and there is an electronically driven fuel injector hanging down in the center of the throttle body.

    3> If your main bearing really was loose enough to cause the Crankshaft Position Sensor to not function; it would be making enough noise to be heard two blocks away. I assure you that this is NOT a main bearing problem.

    4> There have been reports from other '98 Metro owners of problems that seemed to come from a bad crank position sensor. But the real cause turned out to be that this sensor is mounted in the oil pan; and there are aftermarket oil pan gaskets available (probably listed only for Geo Metros; which do not have a crank position sensor) which are significantly thicker than the original part. If the oil pan gasket is replaced with a thicker part; it will move the crank position sensor further from the crank than it was designed to be. And this will cause the sensor to not function at low RPMs.

    5> Please have a cylinder compression test run on this motor. The normal compression pressure on this motor is 195 psi. The minimum allowable compression is 165 psi. If the compression on your motor is less than 165; or if there is more than 25 psi difference between any 2 cylinder pressures; the motor will not be able to run properly; and would need to be overhauled or replaced. If your motor passes a compression test; DO NOT change to heavier oil. It will compromise the lubrication at start up; which is the most critical time of all. 10W-30 is the heaviest oil to safely use in this motor.

    5> Another issue which will cause this motor to cut out on re-acceleration is spark plugs which have worn to the point where the gap has become too large. The best choice for spark plugs in this motor is Autolite #XP63 or #AP63. The plug gap should be .043". Be very careful if you check the gap on the XP63 plug; the Iridium center electrode is brittle and will break easily if you put any pressure on it.

    6> A distributor cap or rotor which has become dirty on the inside or outside will cause the motor to cut out on acceleration. So will a distributor cap in which the carbon button in the center has fallen out or worn away.

    7> Spark plug cables which have developed excessive resistance (more than 1,000 ohms per inch of wire length) will also cause this problem.

    8> If someone has moved the distributor position; in an ill advised effort to change the timing; it could cause this problem. The ignition timing cannot be adjusted on this motor; but moving the distributor position will change the rotor air gap; which will cause the motor to cut out on acceleration.
  • tvmogultvmogul Posts: 5
    edited March 2012
    First off - let me thank you for your thorough response - it's great to finally get to chat with somebody who clearly knows this vehicle.

    Ok so let me give you a few new details and maybe ask a few questions:

    The spark plugs are new (with the last month or so-maybe 1000 miles)
    Distributor cap has been checked and is perfect (button and contacts are fine)
    Oil Pan Gasket is original and has never been off

    Except for the time it cuts out (which is on re-acceleration in 5th gear AFTER being forced to slow in traffic) - it runs smooth as glass so would that not eliminate most of those other issues? (ie spark plugs, distributor cap)

    It only seems to do it when the engine oil is hot, not the water (which always stays correct), just the oil itself - after the car has been running for a while.

    I guess what I am asking is, if those above mentioned options were the issue, wouldn't the car run poorly all of the time and not just in this one, rare instance?
  • zaken1zaken1 Posts: 556
    Thank you, for your open minded, intelligent, and cooperative reply.

    We can obviously rule out the pan gasket and distributor cap as a factor here. But the remaining items I listed are still very likely. To understand this; you need to know that this motor is extremely different in the way it runs from probably most of the motors you've experienced in the past. Japanese motors in general; and this one much more so that the rest, typically do not show signs of degradation in performance as they become worn. The only signs of poor compression will be apparent at low RPMs; particularly during the transition from deceleration to open throttle. This is an especially vulnerable area; because the computer cuts off the fuel injection during deceleration, and then turns it back on when the throttle is reopened. Because of the fuel cut circuit; the engine will be slightly starved for fuel during the first moments after the throttle is reopened; and the higher the gear being used at that time; the greater the load the engine will have to overcome; and thus the greater the tendency to hesitate or stall. This is why you experience this only in 5th gear. At what speed do you encounter this? I ask because some people are not sensitive to when this motor is being lugged. It should never be driven slower than 45 mph in 5th gear. If you coast down to 35 mph in 5th, and then try to accelerate; that alone could cause this, on an engine in perfect condition.

    Cultivate the habit of downshifting to 4th whenever your speed drops below 45, and see whether this problem goes away. Downshift again to 3rd when your speed drops below 35 mph; and your little car will be far less likely to burn the valves; which is the downfall of so many mistreated Metros.

    This amazingly responsive and economical car is far too highly tuned for the American public. And that's why it got such a bad reputation with insensitive drivers.

    But as the valves burn, and the compression drops; the engine speed at which this problem manifests will become higher and higher.

    If your car stalls out on transition from decel to open throttle at 45 mph or higher in 5th; then there is a mechanical problem. Low compression is the most likely cause. Poor ignition is the second most likely cause. NGK spark plugs just don't do the job in this motor; even the recommended heat range runs too cold. Autolites are the best thermal match to this motor. Excessively resistive plug wires, or wires which are not fully inserted in the cap or coil sockets; or plug boots which are damaged or are arcing will also do this. So will a low quality distributor cap. I spent years searching for a decent distributor cap for these motors; until I discovered by accident that Standard Motor Products #JH165T (their economy line) is a better quality cap than the so called premium quality caps. You need a cap with tan or brown insulation. The black caps don't hold up in this motor. Beck Arnley #1746959 looks to be another cap with better insulating material; but I have not used one personally.

    If this problem manifests with proper driving techniques; please run a compression test on all cylinders, write down the measured pressures, and post the results here. Also tell me the brand and part number of the spark plugs in this motor. And I'll respond in kind.
  • tvmogultvmogul Posts: 5
    Ok I will run the compression test and get you the info on the plugs and dist cap - in the meantime, lets just assume that it is the compression problem that you stated - since it's not a giant problem currently - let's assume I did nothing and waited until it became a real issue ... how long do you think this engine will last?
  • zaken1zaken1 Posts: 556
    It would be inaccurate and unnecessary for me to guess about the life expectancy of an engine that I have no details about. Since you said you'll run a compression test; it would be far more useful if I answered that question after seeing the numbers in the test results. It would be even more helpful if you were able to provide information about how far you can drive before the motor needs a quart of oil, following an oil change.
  • tvmogultvmogul Posts: 5
    Ok - will do - may take me a few days to run the test but I will do it and get you the results.

    And to answer your oil question - I change it every 2000 miles and have never had any issue of burning oil. I put in almost 4 qts and drain near the exact same amount.
  • zaken1zaken1 Posts: 556
    Your oil consumption report looks very encouraging. I am now having second thoughts about the cause of this problem. I may be able to save you from going through the bother of a compression test, if you can give me some additional information. Do you have access to a volt/ohmmeter? If you do, there are some measurements I'd like you to make. At this time, I would also like to know the details about the brand and part number of the spark plugs now in the motor. If you can also measure the gap; it would be that much more helpful. If you would prefer to not do these things yourself, but would instead have them done by a shop; I can provide a list of instructions to relay to the shop. But the procedures will not be excessively fussy. I just need someone to do them.
  • sprinter4sprinter4 Posts: 1
    edited May 2012
    Sorry, have to disagree with part of this:

    Quote:
    The truth is that the Chevy Sprint engine had hemispherical combustion chambers and a single overhead camshaft; which operated two rows of adjustable rocker arms through solid lifters. That motor had a recommended valve adjustment interval of 30,000 miles. But the Sprint had a bad cylinder head design, and developed a reputation for blowing head gaskets.

    Suzuki either couldn't, or wouldn't, fix the head gasket problem; so GM got their engineers to redesign the head. The head design was changed from a hemi head with two rows of adjustable rocker arms and mechanical valve lifters; to a wedge head with a single row of non-adjustable rocker arms and automatically adjusting hydraulic valve lifters.

    End Quote

    The Sprint does indeed have the adjustable rocker arms, but you will not find a single lifter anywhere. The Metro does indeed have the hydraulic lifters, but zero rocker arms...

    Metro:
    image

    I do know this for fact as I have done a fair amount of work on both vehicles.
  • zaken1zaken1 Posts: 556
    You are absolutely right about this. It has been a while since I was into a Chevy Sprint motor; and when I thought of the design, the image of a solid cam follower came to mind. That was not correct. The Sprint rocker arms run directly on the cam lobes.
  • I have a 1997 GeoMetro and the past two years I have been having trouble figuring out why it wont charge the battery. I have bought a new battery and changed the alternator, but still dies with in minutes.
    I had a few people check the car and the only thing they can tell me is that the alternator is bad. I gone to other places to check the alternator and they say its good.
    Someone told me that maybe something is left on when the car turns off. Everything turns off when the car is off, however it had a added alarm that I wasnt aware of. My dad decided to disconnected and after a few months it drain the battery again.
    Someone checked it and said it wasnt disconnected all the way and completely disconnected the alarm. We tried the car again and it ran for a few days and now its dead again and have to recharge the car.
    I want to know what else could be the problem and how to fix it.
  • zaken1zaken1 Posts: 556
    This sounds like a very common problem that happens with alternators when they are worked on by ignorant people: The alternator has to do two different things: It has to charge the battery when the engine runs; and it also has to keep the energy from draining out of the battery when the engine is shut off.

    Most mechanics know how to test whether an alternator is charging the battery; but only a few mechanics understand enough about electricity to know how to test whether the alternator is keeping the power from draining out of the battery after the engine is turned off.

    My experience has been that the people who work in discount auto parts stores usually do not know how to test whether the alternator is keeping the power from draining out of the battery after the engine is turned off. So these people will "test" the alternator, and then tell you that the alternator is good; when it really is making the battery drain after the engine is stopped. And even some mechanics who work in garages do not know how to do this. It is sad that people who ought to know better often do not know how to make correct diagnoses of alternator problems; but it is a fact.

    I also need to warn you to NEVER let anyone disconnect a battery cable on your car while the motor is running. Some ignorant people will do this because they believe it is a way to "test" whether the alternator is working. What they don't understand is that disconnecting a battery cable while the motor is running will instantly destroy the diodes inside the alternator. A diode is a one way valve for electricity. When a diode blows; it will let the power drain out of the battery when the motor stops. So you can have a perfectly good alternator on a car; but when some ignorant person tries to "test" it by disconnecting a battery cable while the motor runs; they will destroy the diodes in that alternator. And after that; the battery will drain as soon as the motor is shut off.

    Here is a test you can do yourself to see whether the alternator is charging the battery, and whether it is allowing the battery to drain after the engine stops. You will need to have a digital voltmeter to do this. This instrument can be bought at a Radio Shack store for less than $20. Some auto parts stores also sell this tool at a similar price.

    This meter comes with a red and a black cable. There are different sockets on the meter where these cables can be plugged in. If there are more than 2 sockets on the meter; 2 of them will be marked "VOLTS" and the others will be marked "AMPS" or "MA" or "OHMS." For the test you'll be doing; you need to use the "VOLTS" sockets. One of those sockets is marked with a "+" symbol; while the other is marked with a "-" symbol. The black cable goes into the "-" socket, while the red cable goes into the "+" socket.

    There probably will be a rotary switch on the meter. For the test you'll be doing; turn the switch to "DC VOLTS." Be sure to turn the switch off after you're finished using it; so the meter battery will not go dead.

    The meter test leads come with alligator clips on the ends. The car battery has 2 terminals on it, where the battery cables are attached. One of these battery terminals is marked with a "+" while the other terminal is marked with a "-". Clip the black meter lead to the "-" battery terminal, and clip the red test lead to the "+" battery terminal. Be sure that the test leads touch metal, and not plastic. The battery should be charged before running this test. If the battery has power in it; the meter will read about 12.0 to 12.7 volts when it is connected to the battery.

    Now start the motor, and let it idle. The meter should read between 13.5 and 14.5 volts while the motor is running. If it reads less than 13.3 volts; the battery is weak, or the alternator is not charging the battery.. Try turning the headlights on and speeding the motor up while watching the meter. If the meter still reads less than 13.5 volts when the motor is running fast; the alternator is not charging the battery.

    Once you have a good battery and it is being charged by the alternator; shut the motor off; make sure all the car doors and lights are off, and the key is out of the ignition; and then disconnect the battery ground cable from the "-" terminal. Wait at least one full minute with the battery cable disconnected, and then touch the battery ground cable clamp back to the "-" battery post. Watch for a spark when the cable clamp touches the "-" battery post. If there is a spark when the clamp touches the battery post, then something is draining the battery. In that case; do not connect the ground cable to the battery.

    Instead; disconnect the heavy power cable from the alternator, and tape up the metal end on that cable so it cannot touch any metal. Then try touching the battery ground cable back to the "-" battery post again, and see if there is still a spark. If there is no spark this time; the alternator has one or more shorted diodes in it, and must be replaced. Please do NOT buy a replacement alternator from a discount parts store (even though it may have a lifetime warranty). Those alternators are worked on in Mexico by unskilled people who do not have the needed parts and do not have proper test equipment. As a result; many, many of these "rebuilt" alternators are bad when they are sold. The only place you can buy a properly rebuilt and thoroughly tested alternator is from a NAPA Auto parts store.

    If there is still a spark while the alternator power cable is disconnected and the battery ground cable is touched to the "-" battery post; there is an electrical short somewhere else in the car. You'll need to have this checked by an auto electrical specialist.
  • pipemanpipeman Posts: 58
    CONGRATULATION: perfect explanation, proffesional touch.
    If i can add a " little" comment:
    sometime the "spark" can be very small, difficult to observe (you can try in the night time). Another way is: If you have a test light you can attached the clip from test light to negative cable from the ground and the "sharp end of the test light to the negative post on the battery (remember that the negative cable is disconnected from the battery and is attached only to the ground ).
    If you will noticed any small "reddish", orange, yellow small light, something is drains the system.
    Next step will be to check and remove the fuses from the fuse box and check the test lights is off.
    YOU ARE CORRECT 1000% - only NAPA is selling perfect alternator, or loco rebuilders electrical shops.
    Thanks.
  • jmizelljmizell Posts: 2
    Pipeman, I feel your reply is mostly correct, however, on most new cars, even when the key is off and all doors are closed and lights are off, there is some current drain due to the continuous feed to the radio or navigation, the clock and various other items which stay in a warmed-up mode all the time. Therefore, you might have a small spark anytime you put the positive or negative cable back on the battery.
  • I have owned a 98 chevy metro for about 2 months now. all was good, until today when I was driving and I noticed my start ups were way slow and my engine is revving way high. example: I will finally make it to 15 mph (after about 2 mins) I will be in second gear and off the gas pedal my rpms will be about 2000 after lightly pressing on the gas they will jump to 4000ish. I switch it to 3rd gear, still going 15mph, foot off the gas will be 1500rpms foot on the gas about 2800ish rps! any ideas about what is going on? oh and also I can go a mile and only be at 25mph with my highest rpms at 4000. I have never had this problem, please help!
  • zaken1zaken1 Posts: 556
    Your clutch is slipping!!! This happens when the clutch disc wears down from age and use. When the clutch disc wears; it becomes thinner; and the clutch pedal has to be lifted further up before it fully engages. This results in less and less free play at the top of the pedal stroke. There always MUST BE at least 1/2 inch of free play at the top of the pedal. If the free play becomes smaller than 1/2 inch, and the clutch linkage is not readjusted to add more free play; the clutch will not fully engage when the pedal is lifted all the way up. And when that happens; the clutch will begin slipping when you apply power. The higher the gear you are in, and the more engine power you apply; the more severely it will slip. It is not unlike driving with the clutch pedal pressed partly down.

    A slipping clutch can sometimes be saved by readjusting the linkage to give the proper free play distance; but if the clutch has slipped too much or for too long; the disc will be permanently damaged. When that happens; the clutch will need to be replaced. This sometimes may only require replacing the disc; but in more severe cases; the pressure plate will have to be replaced, and sometimes the flywheel will have to be resurfaced; and usually the throw-out bearing should be changed.

    If you have the free play adjusted and still are not able to recognize what the pedal feels like when the free play is set to the right distance; PLEASE have a mechanic or knowledgable person show you what to look for and how to check it. And don't let them leave until you are totally confident that you understand.

    Some drivers never seem to develop the sensitivity or coordination to prevent abusing a clutch (partiularly those people who go around with the radio blasting). It takes integration of the sound of the engine with the coordination of the accelerator pedal and clutch pedal movement to do it gracefully. Metros often do not need any pressure on the accelerator at all; until after the clutch pedal is all the way up; in order to get the car moving; but this, of course, cannot be done if you accelerate from stop lights to keep up with the impatient people who predominate on the roads these days.

    I realize that this car probably had the clutch abused by its previous owner(s) and you bought the results of that abuse. But Metros are delicate, sensitive vehicles; and some people destroy the clutches, while others destroy the engines. Most Americans are just too impatient and too insensitive to succeed with this car.

    That's a real shame; because I've had my Metro since 1992; and it now has 304,000 miles on the odometer; while it still has the original motor, original clutch, and original rear brake shoes.
  • malibubmxmalibubmx Posts: 2
    I have a 92 metro with a bad engine, and a friend with a 96 engine. What kind of issues will I encounter making this swap?
  • zaken1zaken1 Posts: 556
    You may not realize that there were at least five different motors used in the 1992 Metro, and at least 3 different motors used in the 1996 Metro.

    Basically, the Metro was made with a 3 cylinder, 993cc motor (called the base model and the LSI); or with a 3 cylinder 993cc motor which was designed for more extreme fuel economy (called the XFI, which was not made in 1996); and was also made with a 4 cylinder, 1.3 liter motor. There were also differences in the motor which was used with a manual tranmsission; compared with the motor used with an automatic transmission. And there were difference in motors which were made to meet 49 state emission requirements; compared to motors which were made to meet California emission requirements.

    So you first need to make sure that both engines have the same number of cylinders; and use the same type of transmission. You then have to make sure the 1992 vehicle is not an XFI model (XFIs have an all black rear bumper; while base models and LSIs have a two color rear bumper).. But you might be able to get by if both vehicles do not have the same class of emission equipment.

    The 1996 vehicles used a totally different electronic engine control system (called OBDII) which would not be practical to adapt to a 1992 vehicle. So you would need to use the 1992 intake manifold, throttle body, distributor, ignition coil, igniter, computer, and wiring harness with the 1996 engine. These parts should be directly interchangeable. There are one or two sensors on the 1996 motor which are not used on the 1992 motor; so they would have to be left disconnected (and preferably removed). Both motors in both years use the same spark plug and the same plug gap.

    The 3 and 4 cylinder motors use different model clutches; but the 1992 and 1996 model clutch does not change with the years for each engine type.

    The automatic transmission uses the same overhaul kit for both engine sizes and both years (though that does not necessarily mean that the transmissions are entirely the same).

    This should be a straighforward swap; providing the engines are the same type, and you folow all the steps listed here.

    If you post additional feedback; please list the engine size and transmission type. Also get the emission specification information, from the emission label on the underside of the hood of each car. Thank You.
  • malibubmxmalibubmx Posts: 2
    edited June 2012
    Thank-you, you have been very helpful. I do know both engines are the typical 993cc version and they both have the 5-spd tranny. I will get the emission info and post it, if you could look at that, I would appreciate it very much.
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