1998 Pontiac Bonneville SLE from North America - Comments

15th Dec 2004, 08:52

Ouch! I too got stung by this problem to the tune of $1300 to replace the intake manifold (upper and lower) plus flush out or the motor and new plugs. I too am angry that I was not made aware of this problem that could have been avoided by replacing the manifold. Unfortunately its too late for me. I will not consider another GM product given this problem and GM's lack of concern for their products.

4th Aug 2005, 16:29

You said you can't imagine Toyota (or Honda, etc.) treating a customer this way? Well, read some of the comments written about recent Camry, Accord, Odyssey, Acura, etc. They ain't much better, they just get better press coverage.

14th Nov 2006, 10:23

Yeah, Honda is treating me bad. My 94 Accord with 243,000 miles just had the power antenna chopped off in the car wash and then they said they would replace it for free! Well, I guess Honda likes me!

3rd Jan 2007, 07:16

We purchased this car for my son as a graduation present, it turned into a graduation nightmare. Because of the leak of antifreeze, it ruined the engine. To replace the engine with a new engine it will cost $3,500.00. To replace the engine with a used engine it will cost between $1,800.00 to 2,300.00. GM should be ashamed of themselves if they knew this problem existed.

21st Jan 2007, 12:21

I would like to join the ranks of those with the plastic intake problem. I have a 98 Park Avenue that is presently in the shop having lifters and a new intake installed. I learned from the previous owner that he had the same problem at 49000 miles and replaced the intake and lifters as well. My problem appeared at 108000 and you can well understand why this car will go on the trading block with this track record. It would seem General Motors would build a more reliable engine to put in what was the flagship automobile for 1998. Between this problem and replacing two plastic door handle housings can there be any wonder why Toyota is kicking GM's butt in the auto market. The local service manager at my Buick dealership said the intake problems appear there in an "ongoing" manner. I have a 92Buick Century with 301000 miles on it so I know they can build good engines. I think they should own up to building a dud in the 3800 and fix the problem or do a redesign. My neighbor has a new Lucerne with basically the same engine and after seeing the complaints on the Internet plans to trade that car when the warranty expires. Stay away from the Buick plastic intake engines! they'll bite you hard in the pocket book.

22nd Jan 2007, 04:31

Does anyone know when GM began installing this defective part? I have been looking at several mid 90's GM cars with this engine, yet don't know if they are safe to buy. Thanks!

12th Mar 2007, 22:31

As a GM tech I would love to know what auto back-round you all have. I also know many are very happy with they're 3800's, most people in the industry consider the 3800 to be bullet proof. I'm currently working on one with 290000km the cylinder walls still have the cross hatch in them. I also know there are many factors that contribute to the intake issue, such as coolant condition and exhaust temp as the egr passage goes right by the area of concern. Which can heat the plastic intake to beyond what it was meant to handle. I hope this helps. It's so easy to blame someone else for our misfortunes, so after you buy your Honda and have to replace the alternator for 1000 bucks maybe the old 3800 won't look so bad. Good luck to all.

26th Mar 2007, 16:26

Sorry to burst your bubble, but the 3800 is as bulletproof as the average butt cheek. The problems we are experiencing are real, and probably as widespread and threatening as any GM has ever experienced.

I have a 1996 Olds Ninety-Eight that is leaking - badly - at both trouble spots; at the base of the intake plenum (near the throttle body,) and between the lower intake manifold and cylinder heads. I've been fortunate in that no coolant has yet made it's way into the crankcase, and if any has gone through the cylinders it's apparently only been tiny, atomized amounts.

Financially unable to immediately repair the car or withdraw it from service, I've topped off the coolant daily and kept an equally vigilant watch on the oil for evidence of coolant contamination (...none so far.) Recently, the car has developed severe driveability issues I suspect are linked to burning coolant: damaged sensors and/or the like.

I believe that the coolant leaks quickly multiply once they've begun, and that once a noticeable coolant loss is evident, significant damage has already been done. When enough coolant is lost, the plastic plenum is suddenly very vulnerable to the hot EGR gasses passing through it, and the rubber & plastic lower intake gaskets are also likely deformed. In addition, the exaggerated expansion and contraction of the aluminum lower intake probably deforms the bearing surfaces under the bolt heads and/or stretches the intake manifold bolts themselves, meaning they are subsequently "loose."

I will know much more in the coming days, as I've bought the parts and tools necessary to make the mechanical repairs myself. When done, I'll take the car for diagnosis to address it's driveability issues and hope that I can afford to correct them.

In my opinion, GM began making trouble for itself when it started doing away with diverse products made by different divisions for different people. If this engine were only in Buicks for example, GM would not be as badly hurt as it will inevitably be by this screw-up. Instead, GM now puts a few common engines in all of it's car lines, like putting all of it's eggs in one basket. It's big trouble when an egg-basket this big gets dropped, and now more than ever I wish my Ninety-Eight had a truly bulletproof engine: a good old steel and cast iron Rocket V8.

1st Feb 2008, 11:17

I have owned 4 Bonneville's in the past. Currently own 3 of them. The 3800 engine is the best engine in the world. This coolant / manifold leak problem is a $200 fix.

I just made a 1000 mile trip in my '95 Bonne. Got 34mpg. Toyota and Honda don't come close. All you guys that want to sell your car with a 3800 engine in it... I'll buy it.

2nd Oct 2008, 12:45

This intake on the GM 3800 has been a problem since I owned the car. I Have a 95 Bonneville I purchased in AUG of 94. This has been the worst car I have ever owned maintenance wise. I am on my 2nd motor and have replaced the plastic plenum on that motor 3 times. Twice in the last 6 months by GM. The list of the other repairs can go on forever.

2nd Oct 2008, 15:54

You should get a new mechanic. Replacing the manifold twice in 6 months means someone is doing a bad job. I have the 3800 series II in my car. The manifold was replaced in 2003, it probably had around 80k on it then.

I bought the car in 2006 (108k miles). I have yet to have a manifold issue and I drive my car every day and currently have 144k on the clock. If it was replaced with the improved manifold it shouldn't go bad that that soon, period.