Hello

My uncle has a '97 Buick with a 3.8. It was a freebie a few years ago from a long time customer who moved south or otherwise. It had a spun bearing, and the engine was rebuilt about 5k miles ago (3 years). No warranty left in the engine rebuild.

It's been running rough lately, and has been using more fuel then it should. At times, it will stumble, puke some blue smoke from the tail pipe, and then drive fine. It threw codes for the PCV, EGR, and IAC (all with erroneous readings), I changed them all (EGR/IAC were junkyard parts) The only noticeable change was after I did the PCV, is that the stumbling/puking happens less often. I used a new kit (springs, seals, and the pcv itself)

On a hunch, I removed the oil fill tube, and the engine stumbled hard enough to throw the serp belt, and then I shut it off. After reinstalling the serp belt, I started the engine without the fill cap on. It's pulling massive vacuum through the oil fill. It is also pulling massive vacuum through the oil dipstick.


I suspect the plastic intake manifold was reused during reassembly, and is cracked. I believe the oil cloud to be from the vacuum eventually overcoming the PVC, and sucking the oil from the valve covers into the engine. I plan on replacing the intake manifold, and using the new updated gaskets.

Can anyone confirm my suspicions on this car?

~Nate

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95 Honda Shadow ACE 1100.
1999 Plymouth Neon Expresso. 2.4 swap, 10.5 to 1 comp, big cams. Autocross time attack vehicle!
2012 Escape, 'hunter" (5 sp 4cyl)

I can give you some mildly related info. My old Nissan Stanza pulled vacuum in the crank case (since new) and it would not run without the oil cap on. It would stall immediately if you removed it while the engine was idling.

On your car, have you checked both ends of the PCV system - the valve side and the breather side?

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

97 would be the series II so i would say pull the intake and can it and put on a new one.what usually happens on them at about 80k miles is the plastic will melt right next to the egr pipe.when this happens it tends to leak coolant under that upper plenum and they will smoke and the exhaust will smell like sulphur.when you do pull the intake a word of advice.pull the plugs as water will get into the intake runners.