30th Nov 2007, 20:17

November 30th, 2007.

We also have a 1998 Buick LeSabre with the same problem as all of the above owners, and it cost us $1,300 to get it fixed. Until we found this site, people told us we were crazy to believe that antifreeze could get into the engine and the oil

Now we see it is a GM defect that they should correct. How can a car freezing up on the beltway not be considered a safety hazard?

13th Jan 2008, 16:03

GM has replaced my plenum once under extended warranty. I did not take the car in for that reason. The service manager called me when the car was being service and told me it had a leak and must be replaced, however they also said they were not suppose to let me know since I didn't bring it in for that reason. I am changing it out for the second time myself (3rd time total). The first time I changed it I thought the engine was ruined because it locked up, but the cylinders were fill with antifreeze. Had to remove the spark plugs to blow out all the water, then had to remove the oil pan and clean out all of the gunk in it from the oil and antifreeze mixture. I also had to replaced the starter which has a ring gear which also is made of plastic which melted. I am now in the process of replacing it for the second time, but this time I caught it in time before the water started mixing with the oil. The lower manifold was filled with antifreeze, but did not get into the oil pan (Lucky there). I also believe GM has a design flaw and should recall the vehicles. I believe that every Plastic plenum will need to be replaced. In my case, I have changed plenums more often than tires.

20th Jan 2008, 15:42

Does anyone know what all years have the plastic problem on the Buick's?

21st Jan 2008, 14:50

Any car with the series II 3800 from 1995 to 2002 but the later years have a better version of the manifold. Look at the review trends and you can tell.

26th Jan 2008, 12:23

I have a 1999 Lasabre with 186K. I noticed I was not putting out any heat and the engine overheating light came on. I thought it was a stuck thermostat, but now I wonder if it could be more. Is there a sure way to know if it is a manifold gasket?


28th Jan 2008, 13:06


Yes it's probably your intake. GO NOW and get it fixed! Then sell it like yesterday.

I just put mine in today. To late for me.


13th Feb 2008, 11:31

I have a 1998 LaSabre with the same intake manifold problems as the rest of you. I am taking Rhonda's advice and calling them. This is the most ridiculous waste of money ever. I have always been a GM person and loved the product, but this time after this happening twice within a year I am not going to buy GM when I buy my next car. This problem is too much to deal with and I have lost my faith in GM in general. Lorraine

17th Feb 2008, 23:28

Same plenum problem as everyone else. I replaced the engine at 38,000 miles because of the water leaking into the cylinders and overheating and hydro lock caused by the hole in the plenum. Now the car is smelling of burnt plastic, which is my tap on the shoulder to let me know the plenum's destroying itself again. This time I'll try the Ken-co kit, although my mechanic said he read something about a replacement metal plenum. Anyone know about this?

Neal in Atlanta.

PS I called Buick C/S and had received the same poor service. They admit nothing, but will give me a coupon for a thousand dollars off my next Buick purchase. With the problems that I've had, the coupon would go unused.

2nd Mar 2008, 18:21

This is a sad time for past Buick customers. I have been a service manager at Buick, Chevy, and

Pontiac and GMC. What in the world is GM doing?

I in the past have seen and worked with quality that GM has always had. They at GM need to own up and take care of their customers. This plastic upper so called plenium intake problem and EGR tube needs to be corrected.

Please take the necessary steps as an owner of a Buick Park Avenue.

9th Mar 2008, 06:16

Well, I too am another victim of the cursed plenum. I'm losing coolant and can only assume this is my problem. I will be tearing into my car this weekend hoping it will not be too late. This is a real shame. My car is a '95 Park Ave. with 96k and I really love the car. I guess I don't really mind fixing this if it cures the prob. I will continue to drive this car since I do like it so much. Wish me luck.

25th Mar 2008, 12:17

I just bought a 97 Olds with the 3.8 v6 and 72,000 original miles. I read these posts... wish I had read them two days ago...

Anyway, I ordered a replacement upper plenum and intend to replace it immediately... what about the lower plenum? I have read about the KEN-CO repair kit, but I can't seem to find it anywhere... any ideas? Can I use it with the new upper plenum???



4th Apr 2008, 14:53

I just dodged a bullet, about to buy this time bomb.. too bad, it looked like a great car.. GM needs to own up to its mistakes.

11th Apr 2008, 21:16

The same thing happen to me with my 98 Buick Regal LS. It only has 98k. Now my motor is blown!!! It will cost me $2700 for a remanufactured motor with 3 year warranty parts and labor. I wouldn't have never bought this car if I would have seen this site!!!

29th Apr 2008, 19:04

I have a 1993 Park Avenue and I am having the same problem, so I don't think it began in 1995. I have no water in my oil yet, but it is leaking on the outside and smoking badly. I have also smelled the burnt plastic smell in my car for some time now, and could never figure it out till now. I do all my repairs myself and I have not tore into it yet. Thank God I have a Nissan I can rely on to get me around. When I get into it, I may have to make my own metal sleeve like that repair kit has. Hopefully the plenum is not completely damaged. I did see you can buy a new one on rockauto.com for 132 bucks.

30th Apr 2008, 18:08

In 1993 GM was still using the series II 3.8 which had the aluminum intake manifold. 1995 was the first year for the series III which used plastic. It is highly unlikely your problem is a leaky manifold. And the melting plastic smell is definitely not your intake manifold.

1st May 2008, 08:38

The series I 3800 was out until 1995. The series II 3800 came out in 95 also but was only on the Park Avenue and Bonneville, but the LeSabre still had the series I 3800 engine.

The plastic intake manifold was on the series II 3800 engine and is what gives everyone fits. But when I do go to the junkyard I do see plastic intake manifolds on the series I 3800 93 & 94 year engine models. But the don't seem to be very problematic, since you rarely hear about intake leaks on them. Also the series III 3800 came out in 2003 and it has the metal intake manifold.