1999 Pontiac Bonneville Engine cooling Problems

“Two intake manifold failures for my 1999 Pontiac Bonneville, 3.8 engine. First one was in january 2003. Now 15 months later, it has failed again after 35000 miles. The first time, repair costs were just over $800. Now I'm looking at a bill of $866. I have read the TSB and many other online complaints that I'm not the only one with this issue of recurring failures. Some have even reported fires in the engine compartments or complete engine failure.”

“In mid may I had a authorized Pontiac dealer replace the intake manifold which had ruptured after a backfire upon initial start of 1999 Pontiac Bonneville with a 3.8 l engine. On june 1, 2004, I was nearly near ended on interstate 80 in council bluffs as I retruned from a trip because vehicle lost power. Took to dealer and they said lower bearing was gone, meaning a new engine. I know there have been numerous consumer complaints. It's more than the cost of a new engine that I'm concerned about. …”

“99 Bonneville, in march of 2004 while traveling at 45 MPH the car back fired and the engine killed, it was towed to a shop and coolant was in the engine. The upper manifold was replaced and gaskets at cost of over $ 600.00. A year later march 2005 the car was making a noise. The Pontiac dealer could not find a problem. On april 2005 the porblem was find, haha , plastic intake was crank, more money. I thing GM sould recall and pay a these defects in there parts. I will fight till the end. I have spent over 1000.00 on there defect, me many many other people.”

“I have a 1999 Pontiac Bonneville and I noticed about 3 weeks ago that the coolant reservoir would not hold any coolant. I took the vehicle to butts motors to have a belt changed and the coolant leak investigated. They informed me that it was the upper manifold and gasket that needed to be replaced. I asked if those parts were part of the emissions system and the gentleman said, yes it is. If you don't get it replaced you'll be spilling emissions all over the place. He then quoted me a hefty price of almost $900.00 to do the work. …”

“The engine's plenum(spelling??) manifold started leaking water. My mechanic said it had "warped". He then told me that GM was having quite a problem with this part. He said he had replaced about 10 of these so far this year. And that his part distributor said there was a nationwide backorder on this plenum manifold. I contacted GM and was told there was no problem or backorders on this part. Would like to contact other GM owners to see if they have had similar problems with this part but don't know where to start. Any help will be appreciated. Thanks”