1st Nov 2008, 10:49

My daughter's 98 Bonneville had the exact same problem at 100,000 miles. It cost $500 to fix and clean out the engine. It's only a $200 fix if you fix it BEFORE you have a problem!

13th Feb 2009, 00:11

1995 Buick Park Ave Ultra. No problem with manifold as the supercharger is all metal. However my leak was the timing chain cover. Coolant destroyed the bearings. I replaced the engine with a remanufactured one from Jasper (Jasper, Indiana) for a cost of over $5,000 installed. I guess Jasper remedies all the GM defects when they remanufacture an engine.

But this was after I spent considerable amounts replacing other engine gaskets, made of cheap plastic, which got brittle over time etc. Another example of GM product defects. The basic 3800 engine is solid, the problem is other cost cutting short cuts that have harmed GM's reputation.

12th Nov 2009, 07:04

I have a 98 Bonneville SE and it's giving me problems with the intake. It's not leaking outside but into the motor. Other than that, I've got my moneys worth.

13th Apr 2010, 22:18

Got my '95 Bonneville 3 years ago. (170,000 miles) Best car I've owned. It currently has just over 251,000 miles now, and is still very reliable. The 3800 engine is still strong. Some problems with the tension pulley for a while, but overall well worth the $.

P.S. This car has been from MN to KY 3 times, and has been used for over 2,000 pizza deliveries in the 3 years I've owned it!!! Never has left me sitting.

25th May 2010, 22:23

I have owned a 1998 Bonneville SE since 2006, and can now comment in 2010 about my experiences after 4 years of ownership.

I read on this forum that the intake seal was a major issue, and so was on the outlook for it. Never had a problem (even drove it to California from Missouri and back) until 2008 when it seemed to not be running quite right. I asked my mechanic if it could be that intake problem (with which he was familiar), he said he did not think so. I took it home, drove it a few more days and it conked out entirely, would not start again at all. It was the intake seal, he did replace it and everything has been fine since. That repair cost me $500 (he replaced the seal plus spark plugs due to fouling). If I could recommend ONE thing for prospective owners to do it would be to proactively replace that intake seal. All mechanics apparently know about this issue and make quite a good living off replacing them. Just do it upfront and avoid a breakdown when you least expect it.

I have also had to replace the A/C compressor right after buying it (three times until my mechanic found an aftermarket one that worked), several other parts that one might expect to need replacing given the miles on the car.

My Bonneville now has 227,000 miles, I bought it at 92,000 used, I expect it will run a good while longer if nothing too major goes out. I really like the weight of the car and the way it handles. It has plenty of get-up-and-go, does well on Missouri ice and snow, and feels far safer than any econobox that gets 35 mpg or more. This car is a big luxury car with all the "bells and whistles" and still gets about 25 mpg.

I have had NO issues with my window motors or any other luxury on the car (lucky I guess), judging from other's experiences. I am currently thinking about buying another car and have checked out newer Bonnevilles. Here in Missouri they sell for anywhere from 4k to 7k. If I can get as much use out of a newer Bonneville as I have had from this one, I would be entirely satisfied.

I think that like buying any used car, it's a gamble. I have been lucky this once.

12th Sep 2010, 17:19

I have a 1998 Bonneville SLE with 167,000 miles on it currently. I have had to replace the upper and the lower intake manifolds. I took it to a GM dealer. They replaced them with genuine GM parts, which means plastic, and which means I will probably be replacing them again in the future. The car is paid for, so I need to make it last. Anyone know if they make after-market manifolds that are more reliable (i.e. metal)?

I put 1,000 miles a week on this car, averaging between 23-25 mpg highway. I like the car, I always have. One manifold replacement was covered by a warranty I purchased, the other wasn't (approximately $800 for new manifold, coolant, oil/filter, and sparkplugs), fixed the A/C compressor (lifetime warranty), blower motor replaced by me, and I have replaced the coolant system (water pump leaked as did the radiator, and I had a buddy replace it for less than half what I was quoted). Bought in 2003 with 84,000 on it, she's still going strong. Body is still in good shape, and I'm rapidly approaching the point where I have to put my third set of tires on it. I hope it lasts another 10 years! It's nice not having a car payment.

17th Nov 2010, 13:03

I am selling cars for Chevrolet now and am sad to hear about the gasket problems. Just traded for a 03 Bonneville and after looking under the hood found the same leaking coolant as described. It would build product faith if GM would correct this problem and fix the bad gaskets that are out on the road. Of course I feel they should make everybody's stock good before offering more stock for sale.

4th Feb 2011, 14:46

Same problem with our 98 Buick with the 3800 engine. I thought it was the best engine made, and could be except for the anti freeze leak. Too bad GM didn't inform the public. We lost the coolant and had the problem fixed, but the initial coolant loss evidently loosened a bearing. The mechanic said it was OK, but had a slight tick. Eventually our engine gave out on a trip in the middle of nowhere, and it resulted in us buying a new car. We are talking about a lot of money, which could have been avoided with a recall or warning from GM. Not happy.