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Chevy Venture Engine Problems

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  • jeanzjeanz Posts: 1
    Haven't had this issue with Venture but other GM vehicles would overheat then cool down with heater full blast. With these vehicles a thorough radiator flush completely solved the issue, also with these vehicles the flush was an annual event, at 13 months all would over heat again.
  • Just out of curiosity, if you let the engine cool down to the point where you can remove the radiator cap, shouldn't you see fluid moving from the upper radiator hose (furthest from cap on top of the radiator) through the cooling fins back tot he lower hose once the thermostat opens?

    I don't see any fluids moving on mine, my thought is water pump and/or thermostat. The top radiator hose gets warm but not hot, and the lower hose is ice cold. Only takes about 2-3 minutes for the engine to go from zero to 50%, then another minute to get to 75% of the gauge.

    Thoughts?
  • First,

    IMO, there is no issue with Dexcool and sludge. the "sludge" is an supplement/additative GM added to the coolant as "insurance". it's basically ground walnut shells, and ginger root. Cast aluminum is pourus, and this can seal up any micro leaks. this will easily pass thru any coolant system, and when it does, it'l be ground up by the water pump. when exposed to air, the mixture turns to a jelly like rubber sealant.

    Second, I would suggest anyone that suffers from the cold coolant in the overflow, or temperature fluctuations, cold heet in cabin to have their thermostat changed, but have a 1/8 hole drilled into the outer portion of the t-stat. (between the thermo mechanism, and where the rubber gasket is. seems the 3.4 does indeed suffer from HG issues, but it is made worse by the fact that when the thermostat is closed (on a cold engine), or a running engine that's moving down a cold highway where the thermostat closes for some time. what happens is that tiny amount of air bubbles (less than a cup full) float up to the thermostats thermo sensor, and prevent the thermostat from properly detecting the temp of the coolant!. it varies, because if you make a turn, are on a bouncy road etc, the coolant will splash up & sometimes open the stat enough for you not to overheet, but you will see it on yor gauge as fluctuations. by drilling a hole, your 3.4 will indeed maintain it's 195 degrees, BUT any air trapped under the stat will be forced up to the highest point in the coolant system (luckily the cap), and as the pressure increases, it will be slowly expelled without damage to the overflow tank. Sometimes, small amounts of coolant will be dripped into the tank as well (even happens with a healthy engine), but during normal driving with acceleration, some of you know that the cooling system has a vaccume where it sucks in. - seen by a radiator hose collapsing a little or getting soft on a hot engine. - the good news is that the hose in the overflow tank is submerged in coolant, and it will suck that in, and not the air. as the pressure in the cooling system gets to operating temps, and 15psi, the amount of exhaust gases squeezed into the system diminishes. DO NOT USE HG IN A BOTTLE. you fill screw up the entire cooling system.

    BTW, many cars have self purging systems that resolve this issue unfortunately not the 3.4 we must make it ourslves.

    GOOD LUCK
  • Hi, I've recently had the intake gaskets replaced, 200,000 kms/162,000 miles. I was smelling the coolant in the cab and could see some leaking on the engine. Works great, like new except there is a reduction of fuel mileage from 33-34mpg to 29-30. Mechanic does not have any ideas.
    Anyone out there encounter same?
  • neustkgneustkg Posts: 35
    Wow! How were you getting 33-34mpg? At best on the highway we got something like 30-31mpg but that was when we were keeping the speed between 65-70mph. We drive across Wyoming and Idaho once a year and since the speed limit is 75, we keep it between 75-79 and get an average of about 27-28mpg (which makes sense due to the higher speeds) depending on the wind. You pretty much have to drive at least 75 or you get ran over by semis (hypermilers would be in danger on these highways).
  • I have to clarify that I was doing 60 mph most of the time, on repeated long trips and this is in Imperial gallons, which are larger than U.S. Gals., also using nothing but Shell gasoline. Alas I can't seem to recover my former fuel mileage.
  • I might of found a very effective way of ilemminating the air pockets in the cooling system with out opening the bleed off valves all the time. My daughter has a 2002 Venture and has been having problems with over heating and no heat for defrosters or interior of the van. A mechanic changed the thermostat, but problem remand. Everytime we bleed the cooling system, it would go away for short periods and we had heat in the van. I had an idea, thinking of the old cast iron radiators in homes with the pressure relief valves, these are closed loop pressurized systems, and they had automatic bleeders to remove any air pockets, so why wouldn't this work on the van. Well, I found one thru a McMaster catalog for $26.78, Installed it and right away it started working as thew van should of. The valve is made by Maid-0-Mist and is called Auto-Vent No.78. All you have to do is remove the total bleeder assembly on the passenger side of the motor, and screw the automatic bleeder valve with the 1/8" NPT valve body directly into the bleeder port. Done, about three minutes and no more overheating problems and instant heat/defrosters in the van again. Doing research, it looks like you can order these automatic air eliminators right from your friendly Ace Hardware stores for a cost of $10.00 to $15.00 dollars.
  • Does anyone know the true answer to this problem???
  • WOW KellerMeier - that's great you got this going. I am curious how this works out in the long run. I just did a Head gasket job on my Venture, and the gasket was intact, but the head had a small warp that the machine shop milled out. I'm sure your solution will work for many 3.4's that have a very minor amount of air entering the coolant - that reaks havic on the ability of the water pump to move the coolant thru the block. aside from the 1/16 drill hole in the stat, I also thought of using a 180 degree stat to keep the block 15 degrees cooler, and thus reduce the amount of expansion on the aluminum heads. Unfortunately because of emissions standards, it will be hard to find anyone who will match up a 180 to a 195 & sell it to you.
  • russ23russ23 Posts: 25
    What problem?
  • Yes. I know.

    The 2 heads are aluminum & the block is cast Iron & each has a different rate of contraction & expansion. the head gaskets are made of multi layered steel (MLS). If the cooling system is not maintained properly (not kept full, car allowed to overheat etc.), air is trapped in the cylinder heads, and form hot spots, and the expansion/contraction is made worse. additionally the head gaskets themselve (steel), can begin to rust. All that is needed is a little leak between the cylinder portion of the gasket, and the coolant portion of the gasket, and you will get air pushing into the coolant.
    think of it like this oIO where "O" is the cylinder, and "o" carries coolant thru to cool the engine block. if "I" rusts and breaks down, compressed air from "O" can now get into "o" and causes the car to overheat.
    best advice if your Venture is OK is to keep that overflow tank filled to the line with 50/50 dexcool. If you have to keep filling it up, you have a leak, and you really should get it fixed. - these vans are really reliable if taken care of. Unfortunately for those of you who purchased 2nd hand, you have no trustworthy way to know how it was maintained. everything on this van is simple and straight forward.
  • fred150fred150 Posts: 1
    Not calling you a liar as much as i'm calling myself stupid..If someone can be kind enough to explain i sure would be appreciative..The maid o mist thing is designed to vent at 75 psig and the radiator cap does the same thing at 15 psig or a whichever one it is.Soo how can the maidomist vent before the caps does??
  • Here's my experience with the 98 venture I own. After a year of overheating issues I replaced everything in the cooling system. Here's the list...radiator, hoses, heater hoses, engine coolant temp. sensor, relays (all 3) maf sensor, egr valve gasket, thermostat, water pump, upper and lower intake manifold gaskets (twice), the upper intake manifold (try finding one of those in a junk yard, tons of engines without the intake manifolds on them) and rebuilt ecm. After replacing all this the first few times it overheated (according to the gage) I 'bout blew my top. I took it to a reputable shop and has them diagnose it. They checked the block for minute cracks (none) and then let the engine run for 4+ hours to check the temp. It never overheated but the gage showed it running hot. The official verdict was this, since the coolant temp sensor AND the ecm were new, the sensor wasn't correctly calibrated so the ecm was reading that the engine was hot. Temp at the sensor was 225% when the fans came on. Runs great now, I just don't worry about the temp gage until I see steam!
  • How long should a radiator and water pump last?
    2002 Chevy Venture runs hot all the time and recently got well into the Red zone.
    Mechanic says its needs a new radiator and water pump but he did that 4 or 5 years ago.
    Is 500.00 a fair price for this job?
  • russ23russ23 Posts: 25
    There is no magic timeframe for radiator or water pump life. Pull radiator cap and look at the seal and inside of the radiator. If it is muddy brown, that means your anti-freeze has gone bad. The GM a/f is Dexcool and has a habit of turning to a brown (acid) sludge if not changed frequently. Changing it does not fix overheating since the damage is done with the muddy a/f that gums up everything and eats cylinder head and intake manifold gaskets. To make your life more challenging, there is no known cleaner to clean the coolant out of your car. EPA has eliminated most of the heavy duty cleaners. The most common cause of overheating is failure of the cylinder head and/or intake manifold gaskets. So just changing the radiator/waterpump may not fix the problem. A cheap way to tell is to pull the thermostat and run the car and see what happens. You need to do a block test to check for combustion gasses overheating the coolant. That tester is $50 at NAPA (turns a blue liquid to yellow if you have a cylinder head gasket leak. If you are losing coolant, this may be your problem. Of interest, how does your heater work? A dirty radiator also means a dirty heater radiator. That small radiator acts as a filter and it clogs easily.
  • ybkybk Posts: 1
    Here is the technical discussion on throttle position sensor (TPS) and high idle.
    When throttle is closed Powertrain Control Module (PCM) sees about 0.5 (plus minus 0.2 or so depending on a particular sensor) Volts. When ignition is turned on PCM records the voltage as 0% throttle.

    If TPS is worn out or wires are loose the voltage may drop below initially recorded by PCM and PCM will assign 0% to a lower voltage, for example 0.3 Volts. As a result the original voltage of 0.5 Volts is interpreted by PCM as 4% open throttle, enough for PCM to start thinking that throttle is partially open and stop idle control loop completely.

    Check engine light goes on only when TPS voltage drops below 0.2 Volts or so.

    I was only able to figure it out after borrowing a professional scan tool and monitoring sensor data while driving.
  • Hello eveyone, just wanted an opinion from all you experts about why my transmission still seems to slip after just getting a rebuilt one put on. Literally within 1 week of rebuilt one put on, same issue back again. Van has 143k on it and tranny has felt like its slipping past 3 years. Before new tranny it was slipping getting on ramp on hwy and then at 60-70 speeds. Now its slipping on hwy again AND in town since new tranny put on? Any ideas here are greatly appreciated.
  • russ23russ23 Posts: 25
    The obvious answer is to take the car/trans back to the company that rebuilt it and say fix it. I am not a trans guy, but I own a 98 Venture with 165k and the trans runs as good as the day it was installed. I am not the original owner, but the previous owner did do maintenance on it so I presume the trans was serviced. I had the trans serviced at 140k. The engine is another story, it is the second one that died at 135k.

    Here is my thinking. It just so happens the trans in the van is UNIQUE only to 1997 and 1998. It is called a GM 4T60-E transmission. You might want to google Wikipedia 4T60E. It gives a lot of good info that might be relevent to your situation. A key issue here is that trans came in 12 different combinations and it is possible the wrong parts were used. You say your trans was rebuilt. Does that mean the original trans was rebuilt or they exchanged it with another that was supposedly rebuilt? It makes a difference if they installed one of the other 11 different trans into you car. Another thought is in 1999 the trans was changed to a 4T65E. Not sure but remotely possible one of those was installed and it was not intended to work.

    Since the trans has the same problem of the original, it is highly likely they just screwed up in the fix especially if they did not change out the torque converter.
  • I purchased a used 2002 Chevy Venture last year. It started leaking water into the floorboard and then overheating. So we changed the heater core. The problem got worse. So we changed the thermostat, and found that the water pump was leaking so we changed that too. The overheating got worse. The leak in the floorboard got worse, so we changed the heater hoses and found that one of the clamps was bad allowing water to leak into the floor boards. We did a compression test, and it has good compression. However, we cannot drive it for more than a mile without it completely overheating. We cannot figure out what is going on please help. Also I don't know if this is relevant but the heat does not work either.
  • russ23russ23 Posts: 25
    Continuous loss of coolant has probably caused engine to overheat to point of no return. Might possibly get by with replacing cylinder head gaskets and intake gaskets. Overheating on this engine very common problem. A used engine from junkyard probably a cheaper fix. I attempted to repair my 1998 Venture with new cam bearings (cam failures also a problem) and when thru it started leaking oil. Ended up with a junkyard engine that cost less to replace than the fix. Have been happy ever since.
  • The engine temperature guage started fluctuating about 2 months ago. One afternoon, I started it up and the engine light came on and then some white smoke started coming out of the tailpipe temporarily. I drove it to my mechanic and on the way there the coolant light came on and then the engine light turned off. Mechanic intially said it was head gasket problem but then decided to change the thermostat. Seemed fixed after that but then just 2 days later temp needle started fluctuating again and getting into the red zone with 5 minutes of city driving. I changed out the coolant temperature sensor and when I did the new one made the temp needle spike all the way to hot and never came down. So, I put the old one back in. A few days after that I drove it on the hwy for a good 20 minutes, got to my destination and randomly decided to open the hood. Good thing I did b/c the coolant was boiling like crazy in the overflow tank and actually spilling out of it. The radiator hoses were hot and the fan had come on. Let it cool for about 30 minutes and drove home with the heat on and had no issues. I brought it to my mechanic and he did a coolant flush and never noticed any problems with anything. He just said it took about 30 minutes to drain out all the coolant. Later, I decided to change thermostat myself since part is so cheap and though possibly the first one was bad. I drove the van for 2 weeks with little to no movement in temp needle. Then needle was showing temperature was hot within 5 minutes of driving and would constantly fluctuate up down, up down, up down etc....Noticed I was not getting any heat into the van. I am the only owner of this vehicle and have maintained it very well. Had head gaskets replaced a few years ago, the water pump 3 years ago, new hoses a few months ago and some other things like a new radiator cap. So currently the temp needle fluctuates constantly, sometimes gets to hot zone and heat sometimes does not work. I'm thinking its either the radiator or heater core is still clogged with that dex cool crap or an air pocket. Any ideas or suggestions would be greatly appreciated.
  • Hi i have a 1998 venter and i have this overheat problem to.
    Does your fans come on because mine's don't. some times they turn on but on low speed. i had to unplug the thermostat sensor and the fans come on on high speed. the draw back is the check engine light comes on. I think its an electrical problem that need to be check. I plan to bypass this problem by having the fans stay on when the car starts. Oh you said that you change the thermostat. you need to bleed the system when the car is hot so it can push out the air thats in the system. good luck.
  • russ23russ23 Posts: 25
    My first guess is cylinder head gaskets. To be sure you need to do a block tester to see if combustion gasses are going into the coolant, which apparently is happening. That tester is available at most parts houses for about $40. A blown cylinder head gasket or crack in the head is allowing combustion gas to heat up the coolant. Dexcool crudes up the radiator and heater core to the point you are not getting adequate cooling and it is highly unlikely you can clean it out. The heater core with smaller passages acts like a filter. To check it out disconnect the inlet and outlet hoses to the core and back flush with high pressure hose.

    Frankly a 1998 Venture (I have one) may not be worth that much money to repair. I ended up replacing my engine with used one out of a 2000 Venture. I understand the LA1 3.4 engine block (see wikipedia) is the same all the way thru 2004. I had to reuse almost all the old parts on my 1998 such as intakes, exhaust, fuel rail and throttle body. The basic block is the same, but the emissions standards are different so all the old sensors have to be reused since the engine computer is set for 1998 emissions. Really hurt to have to throw away all the newer parts. I will say this, when you get the engine running, it is great. I get 19-22 mpg and the comfort is fantastic. Use mine like a pickup truck. The transmission in mine is original and runs as good as the day it was built.
  • Thanks for the responses. I did actually have a test done for a cracked block and it came back negative. I also had some ''surging'' occuring unrelated, which we thought was the transmission slipping. But sometimes it still surges even after we had a new transmission put in @ $2000. Back to the cooling issue though, I have spent well over $600 in the past two months taking the van to 2 different general mechanics to fix the suppossedly overheating problem. So, I am going to take it to the chevy dealer and have them look into it. My wife and I have put way too much money into this van to get rid of it plus it is in such good condition inside and out (plus we cant afford a car payment.)
  • russ23russ23 Posts: 25
    I am not sure how to tackle a surge since that can be a bunch of things. I would suggest looking at the coil packs in the rear of the engine where the plug wires attach. One of the 3 packs on my engine was corroded. I would be curious as to what your vacuum is? Attach a cheap vacuum gage to one of the vacuum lines on the engine and run the gage to a point on the windshield where you can see it while driving. Observe it particularly when you feel the surge. It could be a leaking intake manifold which is very common on that engine. Also do not overlook the PCV valve getting crudded up.
  • bodykbodyk Posts: 2
    Help. 02 venture over heats, and blows cool air in cabin of van, no defrost.

    Flush/cleaned radiator/coolant changed thermostat. NOT loosing coolant in fact, coolant has seemed to back up into resivor. Coolant was at recommend level. checked today to bleed system (no Heat) hose to thermostat is getting hot. Was going to do water pump and drive belt because of squeak and 114k on van.

    I was going to try heater core. but I understand there is one by engine and one in dash of cabin. what one do i do first. I have flushed coolant system every year the past 3 years.

    so could that be a radiator issue if it is backing up not heater core. had all kinds of issues with air when van was new now it seems heating issues. I know I need new vehilcal but I want to try and get heat in van for winter. any ideas.
  • bodykbodyk Posts: 2
    Yes, just wanted to put this out there. after flushing changing thermostat. still had no heat issues. for the heck of it I went and bought a new radiator cap, one that locks down in place. so far, I have heat, no air in lines, not over heating. $8 fix. much cheeper than getting ripped a gm dealership... still gonna do Water pump and drive belt. I have parts and there is a squeak from water pump.. so far so good :)
  • Dear Sir ,
    I am really interest in your solution , I have 3 Cars of 2002 and 2003 Chevy venture ,
    2 of them are always creating air inside I can even hear the sound of the water bubbling when I press Gas with a weak rear heat or sometimes without heat if the car stopped without pushing gas( Same for the front heat), the third car 2003 is perfect with no air in the system at all .
    I spent around 300 $ till no by changing the heat sensor and the cluster and thermostat twice and water pump. with no use . I even went to ACE stores like you adviced but I couldn't find the auto bleeding 78 part . Can you please advice me If your van still running good after you install auto bleeder ??. Please reply my my e-mail address is mohrnb@yahoo.com .
    Sincerely
  • russ23russ23 Posts: 25
    Please clarify the problem of air inside and weak heat?? I am not sure what that means. Do you mean a air/water bubbling sound related to the heater whether off or on? If so you possibly have a cylinder head gasket blown, the heater hose clamps are loose or one of the two heater cores is leaking or clogged. Do you have a drop in coolant? If not, it indicates a restriction in the heater core(s). Dexcool, the anti-freeze will turn to mud if air gets too it. I would pull the thermostat and run the car without it for awhile to see if the sound goes away. If not, it will confirm an internal leak like the cylinder head or the intake manifold gaskets both of which are common failures.
  • Yes , I Can hear bubbling when pressing accelerator . but I have no leaks or clogged from heater cores( water level is steady) at all and the car is not mixing oil and coolant I flushed the car 5 times in one time a lot of mud came out .
    My question is how long you used Maid-0-Mista(uto-Vent No.78) and did it works good I found one online for 26$ check this website:-

    http://dekkasupply.com/stores/maidomist/78.html

    Shall I buy it and install it ,please advise.
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