A Cloud of Smoke after high RPM run??
06-26-2014, 08:11 PM
#16
Race Director
targa996, was there a question in your post, or are you just confirming that you blew out a cloud of smoke?
If "lots of smoke" means you were laying down a James Bond-esque smokescreen, this is not right and needs to be looked into. If it means "it was enough that I was kinda embarassed," that's much more common and not (in my opinion) something to panic about.
If "lots of smoke" means you were laying down a James Bond-esque smokescreen, this is not right and needs to be looked into. If it means "it was enough that I was kinda embarassed," that's much more common and not (in my opinion) something to panic about.
06-26-2014, 10:01 PM
#17
Yeah - the question is "how much smoke is normal "in this condition ? It lasted a few seconds (but yes - a lot of smoke) - after that OK - and no subsequent problems so far ....
06-26-2014, 11:47 PM
#18
Rennlist Member
I posted this earlier today on another thread:
"FWIW I've tracked my car 6 days, 30 sessions so far and only noticed what appeared to be AOS induced smoke during one session. That particular day I was running my oil level totally full (on the gauge and at the notch). It was minimal and didn't affect my oil level. My last track day I went back to around a ¼ below the full notch and didn't notice any smoke. If that becomes more prevalent in the future I will probably invest in the Motorsport AOS."
It was my 5th day, 1st time at LS, that I noticed smoke during a session and on start up after that session. It's the only time I've tracked the car with oil at the full notch.
2nd time at LS last thursday, no evidence of it in spite of running faster laps (but running a lower oil level.) I think you're OK.
"FWIW I've tracked my car 6 days, 30 sessions so far and only noticed what appeared to be AOS induced smoke during one session. That particular day I was running my oil level totally full (on the gauge and at the notch). It was minimal and didn't affect my oil level. My last track day I went back to around a ¼ below the full notch and didn't notice any smoke. If that becomes more prevalent in the future I will probably invest in the Motorsport AOS."
It was my 5th day, 1st time at LS, that I noticed smoke during a session and on start up after that session. It's the only time I've tracked the car with oil at the full notch.
2nd time at LS last thursday, no evidence of it in spite of running faster laps (but running a lower oil level.) I think you're OK.
06-27-2014, 03:33 AM
#19
Race Director
I had several instances of post-autocross smoky startups with my 986. I never had any other symptoms or indications that anything was amiss. People more cautious than I may advise differently, but the M96 is known to do this every so often. In my book, it's filed under No Big Deal.
06-27-2014, 08:48 AM
#20
Burning Brakes
I had the mysterious blue cloud of smoke happen once after track run with my X51 equipped motor this year. Ha ha I smoked out the Corvette parked next to me in the paddock. After checking all the usuals visually, I went back out with no issues. Trust me, I had my eyes on the gauges the whole time. Coming back in, I hunted down one of the Porsche tech specialist that knows these motors well. When I told him what happened and asked if I should be concerned he basically said "that's nothing to worry about. These motors like to burp once in a while". I've completed five more track events since that one in March and it hasn't happened again.
I now typically run my oil level with one or two bars below full when cold. It comes up a bar when the oil gets 'track hot'.
I now typically run my oil level with one or two bars below full when cold. It comes up a bar when the oil gets 'track hot'.
06-27-2014, 11:47 AM
#21
Race Director
I know this is an old thread - but I just had the same happen on my '02 996 at Laguna Seca this weekend - 20 minutes high speed run - let car sit for 90 minutes and then lots of smoke out of the exhaust on restart. I didn't let the engine idle after cooldown lap - someone said you need to do that.
On run home and subsequent start - no problems. Yep, oil is definitely getting into the intake (via new AOS?) or cylinders somehow.
I was running street tires (Sumitomo) and stock suspesion - not ultra aggressive on corners or braking - but definitely much harder cornering than on the street. This was my first time on the track in this car - back-end becomes light as you go over hill on front straight (I had PASM kicking in a couple of times under breaking there - with back end wagging at 100+MPH) and PASM caught the back-end coming around on a couple of the lower speed corners - but car is overall amazingly stable, grips well - and was keeping up well with with a 993C4S & 2011 gen Cayman S. (my targa model has softer springs and narrower tires than standard C2 I think - plus slight weight penalty). One guy totaled his cayman at the corkscrew on one of the last runs of the day - crazy to push it that hard at a DE event - but I did see a few spins and offs !
On run home and subsequent start - no problems. Yep, oil is definitely getting into the intake (via new AOS?) or cylinders somehow.
I was running street tires (Sumitomo) and stock suspesion - not ultra aggressive on corners or braking - but definitely much harder cornering than on the street. This was my first time on the track in this car - back-end becomes light as you go over hill on front straight (I had PASM kicking in a couple of times under breaking there - with back end wagging at 100+MPH) and PASM caught the back-end coming around on a couple of the lower speed corners - but car is overall amazingly stable, grips well - and was keeping up well with with a 993C4S & 2011 gen Cayman S. (my targa model has softer springs and narrower tires than standard C2 I think - plus slight weight penalty). One guy totaled his cayman at the corkscrew on one of the last runs of the day - crazy to push it that hard at a DE event - but I did see a few spins and offs !
If you take a cool down lap and then let the engine idle this gives the engine time to shed its heat load and for temperature gradients to moderate. It also will have the intake heating up some which helps the oil on the intake walls to run down and be burned by the idling engine.
If you instead shut off the engine right away, the oil will still run down but of course collect on top of the closed intake valves or run into the combustion chamber if the valves are open. Then upon the next engine start you get the cloud of oil smoke.
Absent any other signs of engine distress: CEL, rough idle, hunting idle; there nothing wrong.
You can lessen the odds of this smoking happening by ensuring the oil is fresh -- I was told/taught when showing up at the track or auto-x to have fresh oil in the engine -- and that the oil level is not too high. I would not have a problem with the oil level at the max line measured when the oil was up to temperature. I would not be in favor of running the oil below this max line as an attempt to prevent the smoking. While the smoking can be an embarrassing event it is not harmful to the engine.
However, running the engine low on oil while on the track could result in the engine oil pump ingesting if not air oil that is not sufficiently defoamed. If either of these occur, this can be extremely harmful.
