Hootchi

At a recent track day last week my car would push out a ton of white smoke when I would first start the car before every run.(only after the first run and in between) After about 30 seconds or so it would disappear but, it was pretty heavy. Any ideas as to why this happens? It does not do it under normal operating conditions.

Patrick

Discussed many times, use the search function. I say it is normal if not every time. Others say it is bad. My experience has been that if your oil level is right at the top, this will happen more often.

Palting

Embarrasing, isn't it? So long as it's brief, only on start up, and only at the track after a hard run, it's supposedly normal. As Patrick said, I get it most when the oil level is all the way to the top, never at half-way mark.

Hootchi

Hey thanks Palting.....yah, a few people at the track said it was normal but, my car seemed to do it the most....with the oil being about 1/2 litre down. Anyone know why this happens?....it was a great day anyway!!!

bowmanm98

When you're cornering hard the oil gets shoved against the side of the engine causing some oil to pass by the cylinder. So when you restart the car the oil is trapped in the combustion chamber and it's burned. That's the white smoke.

The way to avoid this from happening is to return to pit road or your parking spot and leave the car idling for about 2-3 minutes.

cdodkin

Cause: Oil residue under the pistons heads.

The 996 engine uses a flat six cylinder design. Because of this construction, oil residue remains under the piston heads and burns off at every start up.

This can produce a white puff of smoke. It should only last a few seconds. This is normal, and no correction is necessary.

Happens more at the track as you are running fast and hard, and then stopping fairly shortly afterwards - with the engine hot but off, you're probably getting more oil past the rings and under the piston heads under cornering.

If it continues after more than a few seconds it can be a sign that the air/oil seperator is failing, spraying oil into the pistons.

This causes smoke and can damage cats and mess with your o2 sensors.

Oil sperator failure is fairly common on 996/968 etc.

Chris.

Hootchi

Wow....great stuff.....I guess Ill have this checked out on my next service. Thanks all!!!!

Darren

Yeah, normal, but idling doesn't seem to solve the problem for me, still happens, I just ignore it. Now that there are a lot more 996's at the track, people are getting used to seeing it.

Chris 996

Thanks for the answer. It make sense!!!

mooty

i have tracked several m96 motor'd cars.
some have more white smoke than others, some got none. i tend to overfill oil all the time and have blown out the cat that way, but never had (i think) air/oil separator issues.

is there a way to definitively chk for air/oil separator failure other than white smoke? i mean can i access the separator easily.

LiveNupe

It's happened to me twice..... after getting off the track and shutting the engine down without letting the engine cool off properly. The first time it happened, I didn't connect the dots. Now, I ALWAYS make sure I drive the car at low speed for a couple of miles and let the engine idle for a while before shutting it off after each track session.

TT Gasman

The smoking is common, but not normal. I notice this on a lot of 996s, IMO it's a function of the "integrated" dry sump and hard, high G turns. My car has never smoked at all and I have been tracking since new, so not all cars seem to be affected.
In addition to idling after a run make sure the last cool down lap is just that, a nice easy lap around the track.

Darren

If your car isn't doing it, maybe you aren't driving fast enough I know some people who don't have this issue, but they are also gentler on their cars. Those of us who are rough on our equipment seem to have more of an issue.

If it was caused by high G forces, you'd think it would happen on the track, not off the track -- as soon as the oil goes into the combustion chamber it will burn. I suspect it has more to do with the oil atomizing in the engine and condensing in the cylinder after shut-off (which is why letting it cool down seems to solve the problem for some people). My 944T did this same smoking thing if I don't let it cool down, in that case it was oil vapor condensing in the PCV system and so I removed it and installed a catch can.

Joe2000C4Cab

Funny, "hot walking" for a car!

LiveNupe

I thought the 996's (except for the GT2 & GT3) didn't have dry sumps. Am I missing something???