Hi everyone, have 1996 3800 V6 engine. Noticed loss of power, white smoke out tailpipe and loss of coolant. Almost overheated but stopped before it could. Started working on it yesterday. I got down to taking the intake manifold off and noticed coolant had filled one of the intake runners right up to the fuel injector. I cleaned out most of the antifreeze and pulled the plug on that one. Tonight i will try to get as much of the coolant out of the cyl. as i could. I checked the intake manifold gasket and the plastic manifold but did not spot any failure points. I am assuming that it was the gasket. Could it still a head gasket failure that caused this. I want to be sure before i go ahead and replace gasket and put everything back together. Thanks for any help.
Driveway Al

Head gasket failures are pretty rare. If it were the headgasket, I'm not sure how coolant would fill the intake runner. By "intake manifold gasket", do you mean the one between the upper and the lower or the ones between the lower and the heads? It's the latter that tend to fail.

It would be wise to drain the oil and replace with new stuff. Then change it again shortly after running it again.

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I’d be willing to bet based on what you have described that it’s the UIM. Mine was cracked where the EGR tube is between the water passages. When I removed the UIM the LIM was full of coolant. But before I went too far run a compression check to make sure.

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LocoWBL

Here is the cause and solution:

http://www.pontiacbonnevilleclub.com/fo ... =53&t=1061


http://www.pontiacbonnevilleclub.com/fo ... =53&t=3591
and
http://www.pontiacbonnevilleclub.com/fo ... f=53&t=159

Follow those 3 Techinfo articles, and you'll fix and prevent a serious flaw in the original design, giving you years of service. But.....YOU MUST DRAIN YOUR OIL IMMEDIATELY. If moisture sits in there too long, your bottom end may fail within miles, weeks, or even short months after the original failure.

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