PontiacBonnevilleClub.com

Hello,
I Have a 2000 Bonneville SSEI. I am having a few issues and i am concerned it might be a cracked head gasket, I bought the car a few months ago, its supposed to last me a long time so i want to get to the bottom of this problem as soon as possible.

1. I stared to notice that after i shut my car off after a drive, some white smoke still comes out of the exhaust, It is Winter In Michigan so i was hoping it was just condensation but i am not sure.

2. When i start the car, and let it sit and idle, there is a small chug, or shake to the engine, i replaced spark plugs and wires chug is better but still there.

3. I changed the oil and got a coolant flush a few days ago. today I took the oil cap off and discovered some white foam on the bottom of the cap and some smoke was coming out. the oil level is fine. coolant seems to be a bit lower than when i got the flush.

Does this sound like i have a cracked head gasket? are there any other possible problems that could give these signs.
Thank You very much for your time

It is stupendously far more likely that your LIM gaskets are leaking. The LIM gasket failures are uber common. Head gasket failures are uber rare. GM and Felpro both make aluminum framed LIM gaskets to fix this issue for good.

I would also agree LIM gaskets are the most likely issue.

How much should the lim gasket be to get replaced. I doubt I'd be able to do the work myself I would probably take it to a local shop

You can do it yourself for about $100, I would expect $400 - $600 for a shop to do it.

There's a write up for the LIM gaskets in tech info. It isn't that tough of a job if you take your time and pay attention to details.

Yeah, even if the intake gaskets aren't the problem, it doesn't hurt to change them. If they haven't failed yet, they will. I would also change the upper intake while its all apart. The EGR port tends to degrade and warp over time and leak coolant into the intake ports.

When i first got mine, not knowing anything like i do now, I paid a shop to change mine. (with another set of the original designed plastic gaskets, that I have since replaced with aluminum felpro gaskets). They charged about $700 parts and labor for the gaskets (plus coolant and oil change on top of that).

If you take your time and follow the write ups on here, its not a hard job. Just make sure to follow the proper torque specs when putting it all back together. It took me about 5 hours start to finish. The experience and satisfaction is worth the time. Not to mention the money saved.

The op's supercharged engine doesn't have an upper intake.