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Common General Motor's 2.8, 3.1, 3.4 V6's engine problems

rbentonrbenton Posts: 30
edited September 2015 in Oldsmobile
Hi I am have a 96' Oldsmobile Ciera series II 4door with 79K. With 3.1 series 3100 V6. I just found out why car was using coolant for the last six month's. It appear's that one gaskets is letting coolant out the top of the engine. The mechinic said in could be the Intake mainfold upper and lower, head gaskets or the throttle body gasket's. I am wondering which gasket it is? I am wondering how common this problem is? I also like to know how time (aka work is involved to fix). And Lastly how other engine damage I might have. By the way I had checked my oil and it does not show any signs of contaimintation (the oil looking cholatety, or thick and murky).

See Also
The Lost Art of Diagnosing Engine Problems


  • alcanalcan Posts: 2,550
    They tend to leak between the lower intake manifold and cylinder heads. In extreme cases, the intake will reqire replacement due to metal erosion. The problem is common because people still haven't figured out that "permanent" isn't "forever", and the coolant requires replacement every 2 years due to the corrosion inhibitors becoming depleted.

    Mitchell Mechanical Labor Estimating Guide times:
    1984-96 Ciera
    Manifold gaskets................ 5.4
    Head gaskets.................... 9.8
    where A.C. interferes........... .3
    where Air Pump interferes....... .5
    where Cruise Control interferes .. .2
  • What alcan said is right on target. I have a 95 Buick Rgal with the 3.1 V6. I bought it used. To make a long story short, my car had to have the intake manifold and one of the heads replaced due to metal erosion. Mine was bad enough to have water in the oil. The previous owner did not maintain the coolant system. Lucky for me, the maintenance warrenty covered it and there was no other engine damage. That was at 90,000 miles, I now have over 145,000 miles on it and it still purrs like a kitten. I would recommend not wasting time getting it fixed. The longer you wait the more it could cost. Like alcan's post, it will take about 2 days or so for labor. Mine took a week because they had to wait on parts.
    Good luck.
  • My 1997 Monte Carlo overheats after I idle it for more than 5 or 10 minutes. I get the same result with friend's 3.1 motors. The temp needle climbs way up more than I am comfortable with before the fan kicks in. The way I prevent it is to turn on the a/c. Dealer says within specs. I dont think so. Anyone else have this problem?
  • 79377937 Posts: 390
    Alcan is right about metal erosion and gasket leaks. Also right about the coolant. What I do now is siphon the coolant overflow tank empty every 2 months or so and top it up with fresh coolant again. In this way the cooling system is getting a fresh transfusion all the time. It's easy and cheaper in the long run and very simple to do. Just take a length of small hose, prime it with water, ( don't suck it) and dunk the one end into the overflow tank and the other into a suitable container at ground level and drain the tank. Just be sure to get the right coolant for your car and mix as per instructions.

    By the way, Dex-Cool is available at K-Mart and similar outlets at very reasonable prices. Don't buy it from the dealers.
  • 79377937 Posts: 390
    kcwolfpack59, it looks like GM allows their engines to get hot. My 99 Cavalier also seems to get very hot while idling in stalled traffic before the fan kicks in. I'd never let it go into the red though and it never has. Like you say, it does make a person uncomfortable. Seems as if that's the way GM likes it.
  • jeneppjenepp Posts: 3
    Help! I have a 1990 Grand Prix 6 cyl with 199,000 miles. I have had very few problems with this car and have been very happy with it. Up until a couple weeks ago it still rode extremely smoothly and was a comfortable ride. One afternoon on a rainy day, the car would not start. The engine turned over and sounded like it almost started, backfired a few times. The car was under a carport, but there was condensation under the hood. It rained for a few days, and I tried unsuccessfully to start the car the next day. A friend looked at it and thought it was the timing chain. He replaced that, by chance, on the first dry day. The car then started, but since he did not try to start the car beforehand, I don't know if that was really the problem. Four days later, the car would not start again, but this time was different. It acted like a dead battery, but the headlights and interior gauges were still bright. After a jump-start the car started and drove fine. Three days later, again on a rainy day, the car wouldn't start AGAIN, this time the same as the first time, turning over, backfiring. It finally started that night, but then it ran terribly rough. Also, when I held a dollar bill at the tailpipe, it blew out and sucked in. OK- so I drove the car for a couple days. It was very rough. Gradually, it got better, though. By the time I got an appointment with my mechanic, it was fine. The mechanic found no problems. Some things I suspect: an electrical problem, something shorting out because of the rainy weather; also I heard the catalytic converter can cause all kinds of problems on these model cars. Any ideas? I would appreciate any help.
  • alcanalcan Posts: 2,550
    The first thing to check with a wet weather no start is secondary ignition system: distributor cap (if equipped) and plug wires. The symptoms you describe aren't consistent with a plugged catalytic converter.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 57,602
    I wonder if you had a sticking valve that came unstuck with driving......certainly could happen at high mileage, and the symptoms are similar to a slipped timing chain.

    MODERATOR --Need help with anything? Click on my name!

  • jeneppjenepp Posts: 3
    Thanks! I'll check these things out!
  • jeneppjenepp Posts: 3
    If I had a stuck valve, does that mean it will stick again? Or might it be okay for a while? Thanks!
  • 79377937 Posts: 390
    My son once had a German built Chevy Chevair 1.8L. It had the same type of formed rocker arms used by GM today. These had a tendency to break after high mileage and would prevent that particular valve from opening. In one case an exhaust valve rocker broke and the exhaust valve was not opening. That cylinder would fire but, on the exhaust stroke, the gas had nowhere to go and was blown past the piston and into the crankcase. This happened at highway speed. So it was with much bucking and snorting that he managed to chug home a few miles further on.

    I'm not suggesting that's what Grand Prix's fault was but, while we were on the subject of valves....
  • 79377937 Posts: 390
    Sorry, meant to say jenepp.
  • rwingerrwinger Posts: 6
    I just bought a used 97 Venture (130K km) and while changing the oil, the dealer tech told me he could see evidence of coolant condensed on the filler cap. They suggested it was the intake manifold gasket. Is this the same problem as for the 3.1's covered earlier in this discussion? Is it the upper or lower manifold gasket? Is this a common defect with this series of engines, or is it a symptom of poor maintenance? I've heard that coolant replacement is the culprit, but isn't this dexcool stuff good for 5 years?

    Thanks in advance for your insight,
  • alcanalcan Posts: 2,550
    Dexcool (orange/pink coolant) is good for 5 years. The deposits on the inside of the filler cap are often caused by short trip winter driving. Check the oil dipstick for signs of coolant contamination. Is the coolant level in the recovery bottle dropping?
  • lngtonge18lngtonge18 Posts: 2,228
    I have a friend who owns a 92 Buick Century with the 3.3 liter engine. He is having intermittent problems with the car running rough (bucks and misfires) and than sometimes stalling at idle while the check engine light comes on. The car only has 80,000 miles on it. We tried changing the spark plug cables and the spark plugs. The car ran better for a week and than it went back to the same thing. What could be causing this problem? Is it a clogged EGR valve? Any other ideas?
  • stealth1969stealth1969 Posts: 162
    My 95 Regal with the 3.1 liter engine had a somewhat similar problem. I had rough idle and it would miss while crusing down the road. I never had a check engine light though. I had changed the plugs and wires and it did seem to help mine a little also, but did not fix the problem. After time it just got worse to where it was missing on one cylinder. One of the coils for the ignition went bad. It was strange because the coils fire two cylinders but only one was not getting the fire. Replaced the coil and it has been fine since.
  • rwingerrwinger Posts: 6
    I've only had it for a week, and my mechanic (who inspected it before I bought it) must have missed this. The coolant level was low when I bought it - bottom of the reservoir, it took about 750 ml to top it up and I've been driving it very little since then. What would I be looking for on the dipstick?
    The coolant looked like it was a mix of dexcool and regular AF. I say that because it had a green shade to it (it was still basically that fluorescent orange/pink, but it sure didn't look like fresh stuff) Would the intake manifold gasket deteriorate as a result of mixing the two?
  • 79377937 Posts: 390
    Stealth1969, if one end of the ignition coil were shorted to ground you would get the effect you mentioned. The 2 plugs and secondary coil are all connected in series. The coil sees the plugs as 2 capacitors. So, you have a capacitor, coil, capacitor. When a high voltage is induced into the coil by the primary winding, the voltage will travel from the side electrode of one plug, through the coil and to the centre electrode of the 2nd plug. Take off the wire to one plug and short it to ground and, the other plug will still fire. Not recommended though!
  • lngtonge18lngtonge18 Posts: 2,228
    How do you determine which coil is bad? There are 2 or 3 of them no? These are the black boxes where the spark plug cables connect? I kind of figured that area might be a problem since it is normally where a distributor cap and rotor would be located, which is a normal wear item. How much did the coil cost for your car?
  • 79377937 Posts: 390
    intonge18, the coils are marked where the plug wires go on. On the 4 cylinder engine one coil fires plugs 2&3, the next coil fires 1&4. In the case of a 6 cylinder, the coils are marked and fire 1&4, 6&3, and 5&2. Each coil can be individually removed and replaced if needed. I am of course refering to the Direct Ignition System that uses no distributor. Hope this helps.
  • stealth1969stealth1969 Posts: 162
    I pulled one plug wire at a time and attached it to an extra plug. I postioned the plug so the electrode was grounded and would not move, you could use a pair of insulated pliers but be careful not to get shocked, like I wouldn't touch any part of the car then. I had my wife crank the engine while I looked for the spark. As soon as I saw the spark, I had her turn it off. Do this for each wire. I had one were I wasn't getting a spark. Replaced that coil and she runs fine now. The coil cost me about $13 at Autozone. Hope this fixes your problem.
  • stealth1969stealth1969 Posts: 162
    I know I'm not Alcan and he can correct me or add if I missed something. Is your car using coolant? Have you had to add more since the first time? Does your oil level seem to increase? A little goop under the oil cap can be normal, expecially during the winter months. If the head or intack manifold was bad, you should see some coolant loss from the reservior.
  • rwingerrwinger Posts: 6
    Unfortunately, (or maybe fortunately for the engine) I haven't been driving it enough to notice any consumption of coolant. At the time it was spotted by the tech, he was changing the oil, but I also had him flush the cooling system at the same time. Other than the coolant levels decreasing (and if its happening, its not a large amount) is there any other telltale signs that the gasket is leaking? The oil dipstick was mentioned by alcan, but what would I be looking for? I want to avoid driving it too much with this problem, cause coolant doesn't make very good oil. Is there any other way to detect a faulty gasket without running it enough to consume a noticeable amount of coolant?
    Its going to another mechanic tonight to take care of something that was supposed to be done when I picked the car up, so I can get a second opinion from him before I go spending a ton of money.
    How common are intake manifold gasket failures in these engines anyway?
    Any help is appreciated, Thanks
  • stealth1969stealth1969 Posts: 162
    I don't know if is common for the intake manifold gaskets to fail on these egines. I don't work in the auto industry. Let me tell you about my car. I had to fill my coolant reservior every 1 to 2 tankfuls of gas because it was empty even the radiator would be low. I also noticed my oil level would increase, I check it every fill up. At that time I drove 60 miles to work one way. So it was very obvious. It took the dealer 3 times to totaly fix the problem. To make a long story short. The head gasket was replaced 1st, then they tried to patch the head and the intake amnifold, which did not work, so the head and intake were replaced. I haven't had a problem with coolant loss since. Lack of maintenance was blamed for the head and intake needing to be replaced. It took about 3 to 4 months for it to be finally fixed. During that time I put about 7,500 to 10,000 miles on the car.
    On the dipstick, I would look for an increase in the level or if there is a kind of goop like what is on the oil cap. If you trust the mechanic, I would also talk to him about it.
  • rwingerrwinger Posts: 6
    Thanks stealth1969
    Something bugs me about this failure - I'm still puzzling over the reason that (at least for this vehicle - 97 venture) they sell it with dexcool, which is good for 5 years, and then can blame lack of maintenance in the cooling system for the gasket failure. The service advisor at the dealer was quite sure it was the intake manifold gasket leaking, so I assume he's seen this a few times. I've only had it 1 1/2 weeks so I can't comment on what the previous owner did or didn't do but given the van's age, the coolant shouldn't have been in bad shape for too long if its designed to last this long.
    I guess I'm wondering why this failure is common, and usually blamed on the coolant maintenance which only needs attention every 5 years. Should I be changing out the dexcool every two years like the regular stuff?
    A little miffed, Not enjoying spending $$
  • stealth1969stealth1969 Posts: 162
    I can understand what about your frustration. I have a 3.1 in a 95 Buick Regal. I had mine for a month when I saw the problem. A little older than yours and I know more miles. I don't know if they used Dexcool then. Is there any kind of warrenty you got with the van? Did you buy it from the dealer or a private party? Like Alcan and I said, a little goop on the oil cap can be common. Check the dip stick to see if the same type of goop is on it. Also does the oil look different? By all means, I would talk to your mechanic about it. I think he would have checked the condition of the oil when you had him check the van.
  • rwingerrwinger Posts: 6
    I got this thing from a used car dealer/wholesaler. He gave me a 3rd party powertrain warranty with it, but of course gaskets are excluded. I'm working on him to at least cough up 1/2 the repair cost, but he's obviously not interested. He put the onus on the buyer to have it inspected and will fix what's wrong, but after you pick it up, its your problem. I think that he has a responsibility to ensure the car doesn't need major repairs for a reasonable amount of time (at least a month).
    I'll talk to the mechanic and see what he says. I just would like to know that first, it needs doing, and second that it should be OK after as long as I maintain it properly. I like to have my cars in the shop when its convenient for me.
    Am I bitter? A bit.
    Mastercard likes me though.
  • stealth1969stealth1969 Posts: 162
    I know what you mean. It has been about a year since mine was fixed and it has no coolant problems. It now has over 147k miles. I would also check you state laws to see if there are any pertaining to car sales. Would the warranty cover the labor part? That is going to be what costs the most.
  • alcanalcan Posts: 2,550
    Sorry to take so long to get back to you re mixing of antifreeze types. Here's a quote from GM:

    When adding coolant it is important that you use DEX-COOL (orange colored, silicate-free) coolant meeting GM Specification 6277M.
    If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will have to be changed sooner -- at 30,000 miles or 24 months, whichever occurs first.

    The problem is that silicated (conventional) coolant can damage aluminum parts such as the intake manifold and cylinder heads on 2.8's, 3.1's, etc. Re your question as to whether this is common on these GM engines: yes, very. That's why they had to develop the silicate free coolant.
  • kwagkwag Posts: 1
    My 96 Grand Prix also has a 3.1 and as you can guess the intake manifold gasket is bad. For the past few months I have been adding dexcool about every two weeks. After reading through your previous posts I'm even angrier with GM for recognizing this as a problem and then charging ridiculous amounts to have the problem fixed.

    I was quoted by a dealership that it would cost upwards of $700 to have this problem fixed. I think I'll get a quote from another mechanic before I do anything.

    The part that really upsets me is that the entire coolant system is advertised as "no coolant change" for 100,000 miles. What could have caused the gasket to go bad? I never added dexcool coolant to the system until I noticed it was leaking. I have never considered buying a foreign car, but it's expensive repairs like this that make me wonder if its worth sticking with GM cars.

    I now know I'm not the only one out there with this problem. Thanks for the insight.
This discussion has been closed.