Plastic engine intake plenum assy meltdown causing coolant into cylinders of engine. Original incident identified to possible damage to 1st cylinder. Plenum assy replaced with metal sleeve which mechanic claimed was superior to original mfg part. Prior damage to 1st and 2nd cylinders became permanent months later when engine shutdown while driving. Researched recall data and found nothing to date. Mechanic acknowledges problem is frequent and known by manufacturer for long time. Contacted GM and was refused any type of compensation. Researched complaints on NHTSA a found an unbelievable large volume of the exact same problem. Intend to call NHTSA direct and find out status of large complaint base with no action. Intend to contact all others filing complaints for definite immediate class action.

- Bel Aire, KS, USA

1999 Pontiac Bonneville caught on fire in the engine compartment. When the consumer attempted T start the vehicle it's engine backfired then caught on fire. Recently the consumer came across a recall for defective fuel regulator which caused fires. The consumer contacted the manufacturer is awaiting a response.

- Unknown, DC, USA

I've had major problems with my 99 Bonneville, costing me over $2,400. It started at 64,000 miles (6/26/02) with a backfire caused by a faulty fuel pressure regulator, which now has a service recall (a little too late); that cost me $300. A week later, the upper manifold plenum leaked causing the engine to flood and die; I spent over $500 on that little project (replacing the manifold and cleaning the engine). It never ran right after that; I had extremely low gas mileage and lack of power, and the engine light kept coming on and off and it stalled on many occasions. After about six months of this, it died again on 3/22/03. This time, it spun the main bearing and the lower half was ruined. I went to three different mechanics before I could find someone willing to touch it, but I found a good mechanic that rebuilt the lower half (versus replacing the engine) for $1,600. I still have the car and it seems to be performing well, but you never know. IM going to include all of my repair costs for reimbursement (through the fuel pressure regulator recall notice) and see what happens. My mechanic says that all of this is related to the backfire and the plenum leak.

- Duquoin, IL, USA

While the vehicle was parked consumer noticed that fluid was leaking from underneath. Vehicle was taken to a body shop for inspection, and mechanic determined that the head gasket needed to be replaced due to a defective head gasket.

- Morton Grove, IL, USA

My car stalls intermittently, usually in town while braking or turning, or merely slowing down. It lurches when cruise control is set at higher speeds like it's trying to die. It has happened at least 10 times (dying) and 5 times (lurching) in the last 3 days. Dealership unable to duplicate more than 1 time and can't figure out what to do next. Have cleaned terminals and replaced crank shaft sensor.

- Bourbon, IN, USA

There is a recall on GM 3800 series II engines for years 2000 and above relating to the intake plenum. This defect causes serious engine problems. I talked with more than one mechanic who stated that this exact defect frequently occurs in 1998 and 1999 year autos which use the same engine. My 1999 Bonneville has this problem which will probably cost several thousand dollars to repair. I believe this should be covered by GM. Currently, they are not covering 1999 models. This is an obvious manufacturer's defect and should be taken care of by them.

- Gobles, MI, USA

The consumer stated the vehicle stalled which made the vehicle difficult to control. The dealer replaced the oxygen sensor, but the problem continued.

- Pittsburgh, PA, USA

The vehicle stalled without warning, which made the vehicle difficult to control.

- Cameron, WI, USA

I have a 1999 Pontiac Bonneville. The car would not start and I had it towed to dobbs. Dobbs investigated and found that the upper plenum had warped. Thereby causing the starter to fail and antifreeze to get into the engine. Pontiac knew about this problem and corrected it on the year 2000 model. However, they did not do a recall and left us poor saps to have to pay for the repairs ourselves. Since my car is out of warranty, they have said that it is my own problem. I am out of pocket $1,046.96 plus $40 towing fee for a problem they knew about and didn't recall. I wish to be reimbursed.

- Overland, MO, USA

Brakes do not work correctly. Consumer has to stop at a good distant to come to a complete stop. Also, drums have been checked. Last month dealer replaced brake cylinder. Brake problems have caused an accident. Brakes failed frequently since the purchase of the vehicle. The rim cracked during the accident. The alternator and rear wheel cylinder failed. Oil pan gasket failed causing oil leak. A/C failed four times.

- Huston, TX, USA

A bell sounds and engine shuts off. No power at all, causing very dangerous condition. Had to dealer 5 times, and crank sensor replaced, along with computer. Condition still exists which could cause possiable accident with serious injury or death.

- Searingtown, NY, USA

Engine cuts off while driving. Parts replaced so far: Crank position sensor, elect ignition control.

- Chesapeake, VA, USA

While driving and would slow down for stop sign/light, vehicle would stall out. A bell would ring prior to vehicle stopping cold. Would be doing speed limit when it happened. Will be taking to dealer.

- Bethelem, PA, USA