964 C2 smoking problem???

dondlhmn · 12-17-2003, 06:01 PM

I have a 1991 C2 Tiptronic that on odd occasions smokes so badly that I can't see the cars behind me in my mirror. It only does this once in a while and it seems to initiate the smoking upon acceleration. It goes away in seconds, especially if I lift my foot off of the accelator and then press it down again. It doesn't do it most of the time..doesn't smoke at idle or at cruise power settings.. It seems to me that if anything serious was awry, it would smoke all of the time, but maybe especially at higher vacuum power settings.. This makes me suspect that the problem is in the vacuum, crankcase ventilation or some other EPA related system that uses engine vacuum for something. HAS ANYONE ELSE ENCOUNTERED this on again, off again smkoing problem? If so, what was it and what was the cure?? Please contact me at dondlhmn@aol.com with any clues....

Thanks!

AFJuvat · 12-17-2003, 07:49 PM

Need some more information:

Where is the smoke coming from? Tailpipe, engine compartment etc.

What color is the smoke - bluish white? black?

What is your oil consumption? Any oil leaks?

AFJuvat

dondlhmn · 12-17-2003, 08:06 PM

Oh...I just assumed that it would be understood to be oil smoke and from the exhaust..sorry. So it is bluish white as in OIL smoke and it comes from the exhaust pipe. Oil consumption seems to be fairly normal...at least no worse than any other porsches I know of, BUT I really don't drive the car enough to have a good fix on precise oil consumption rates.

Thanks!

FRED/LI · 12-18-2003, 04:37 AM

Too much oil in the system will do it. Drain and refill with 8 qts, warm up and top off to mark with engine running. I'll bet a beer this is it.

dondlhmn · 12-18-2003, 07:50 AM

Fred,

I sure hope you are right! But..using your theory, why would it have not done this at all for the last couple of thousand miles, during which oil was added only once and that at about 1200 miles ago, then suddenly started doing it in the last 100 miles? Again...here's hoping you are right.

Don

FRED/LI · 12-18-2003, 09:33 AM

I'd hate to lose that beer, but you may be able to check the spark plugs to potentially isolate a particular cylinder or determine if it's all six. in that case, I'd lean towards the induction system if all are showing some discoloration. Worst case, rings are worn and letting oil by.
My SC from years past was torn down not too long after I sold it and the piston rings were too weak to even spring out when the sleeve was removed. It too, exhibited the same symptoms you describe.
I'd still bet that it's in the induction or venting...at least I'd hope to find something there.

Porschedude · 12-26-2003, 09:28 AM

Fred,

When you change the oil, try a different brand than you have been using. I experienced this problem with my 2.4L '72 911T. It would start smoking about the time the oil needed changing. I found that some oils worked better than others. I found that heavier weight oils, say 20-50w, worked a little better than straight 30w. I tired straight 40w one time without any problems; just don’t try this in the colder climates. Over the 14 years I owned and serviced the 911T, I must have changed or rotated the brands once per year. It may seem strange, but it helped my smoking problem. This only masked to problem with the engine, which was worn-out cylinders with a whole lot of taper. When I assembled the engine, the taper was right on the edge of the maximum. I drove the car for 12 years / 120k miles with little embarrassment from the smoking.

I started using 15-50w Shell Rotella in my 964 with 114k miles, and no smoking.