Ok, my turn. White smoke today..
10-13-2014, 03:13 AM
#1
Rennlist Member
Thread Starter
Ok, my turn. White smoke today..
Took my 03 996 to a Porsche Club AX today and got a lot of white smoke. The engine has about 1,500 miles on it since it was completely rebuilt last fall with new AOS, IMS, RMS, etc. and it runs flawlessly. After the first run, when I got back into the pits, I saw some smoke coming out behind me. I kind of shrugged it off and thought it might have been brake smoke. After I ran the second run, a friend told me it was smoking from the tailpipes throughout the entire course. I let it sit a few minutes, and then when I cranked it up a pretty good cloud of smoke came out of both tailpipes. You could hold it about two or 3000 RPMs and it would clear out and then if you revved it up, more smoke would come out. When I left the event, it smoked every time I hit the gas for about 10 or 15 minutes. After about 20 minutes or so on the way home, I couldn't see anymore smoke, and when I got home I checked it and nothing and then I let it sit for a while and started it after 15-20 minutes and nothing and right now it is clear with no smoke.
This is the first AX I have taken it to so I'm wondering if this sounds like a typical AOS issue? Or?
This is the first AX I have taken it to so I'm wondering if this sounds like a typical AOS issue? Or?
10-13-2014, 03:29 AM
#2
Race Director
A month ago I was at an autocross and had similar. (also an '03 996)
First run, no smoke. Then, the car sat for maybe an hour until the next run. Huge cloud of white smoke that looked like a NASA liftoff. Smoked much of the run, but at a relatively low volume. By the end of the run, the smoke had stopped.
That was a month ago, not a wisp of smoke since then.
By the way, I changed out my AOS last year.
Also, it's never done that before (smoked) at either the track or at an autocross. Odd.
First run, no smoke. Then, the car sat for maybe an hour until the next run. Huge cloud of white smoke that looked like a NASA liftoff. Smoked much of the run, but at a relatively low volume. By the end of the run, the smoke had stopped.
That was a month ago, not a wisp of smoke since then.
By the way, I changed out my AOS last year.
Also, it's never done that before (smoked) at either the track or at an autocross. Odd.
10-13-2014, 09:03 AM
#3
Rennlist Member
I had a similar experience at a track day. Was your oil level toward the high side? I think the aos more easily gets overwhelmed when the oil levels are full or overfull and then some oil gets burnt off in the combustion chamber and then the smoking stops. I've seen recommendations that the oil be to the low point of full on the dipstick for this reason.
Might all be anecdotal though.
But the stock aos isn't really built for high intensity track work. A new one is as likely to smoke as an old properly functioning aos. Check your coolant reservoir for oil and your oil for coolant. If both are fine you are probably fine.
Might all be anecdotal though.
But the stock aos isn't really built for high intensity track work. A new one is as likely to smoke as an old properly functioning aos. Check your coolant reservoir for oil and your oil for coolant. If both are fine you are probably fine.
10-13-2014, 10:49 AM
#4
10-13-2014, 12:17 PM
#5
Race Director
Took my 03 996 to a Porsche Club AX today and got a lot of white smoke. The engine has about 1,500 miles on it since it was completely rebuilt last fall with new AOS, IMS, RMS, etc. and it runs flawlessly. After the first run, when I got back into the pits, I saw some smoke coming out behind me. I kind of shrugged it off and thought it might have been brake smoke. After I ran the second run, a friend told me it was smoking from the tailpipes throughout the entire course. I let it sit a few minutes, and then when I cranked it up a pretty good cloud of smoke came out of both tailpipes. You could hold it about two or 3000 RPMs and it would clear out and then if you revved it up, more smoke would come out. When I left the event, it smoked every time I hit the gas for about 10 or 15 minutes. After about 20 minutes or so on the way home, I couldn't see anymore smoke, and when I got home I checked it and nothing and then I let it sit for a while and started it after 15-20 minutes and nothing and right now it is clear with no smoke.
This is the first AX I have taken it to so I'm wondering if this sounds like a typical AOS issue? Or?
This is the first AX I have taken it to so I'm wondering if this sounds like a typical AOS issue? Or?
Absent any signs the engine is not running right, and as long as the smoking doesn't return, that's what I would hazard a guess is what happened.
Be sure you check the oil level. I think you'll find it low.
Be sure when you attend another AX event you show up with the engine full -- but not overfull -- of fresh oil.
While I can't be sure I suspect the smoking episode was possibly partially due to oil that should have been changed before the event. While 1500 miles is not that many miles on oil depending upon how the car is used oil can still end up quite contaminated with unburned fuel and water (combustion byproducts) and these can have the oil more prone to foaming and thus creating more oil vapor in the engine which can overwhelm the AOS and the smoking was the result.
10-13-2014, 02:16 PM
#6
After everything JR has posted about tracking an unmodified M96, why are you doing it? I bet you even had the wrong oil in it too. Your lucky your car left the track intact (if it still is). Oil starvation and AOS/OVS issues for the stock M96 are no joke. Consider yourself warned for next time?
10-13-2014, 02:50 PM
#7
Race Director
Jake's posts are awesome, but badgering everyone with reminders of everything Raby has ever said gets old. The people who post here are some of the most informed Porsche owners on the planet, so maybe throttle it back one or two clicks?
If anyone needs me on 11/9, I'll be at the stadium tempting fate by autocrossing my unmodified 996...WITH THE WRONG OIL Z0MG!!!!
If anyone needs me on 11/9, I'll be at the stadium tempting fate by autocrossing my unmodified 996...WITH THE WRONG OIL Z0MG!!!!
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10-13-2014, 04:19 PM
#8
If the smoke started right when you started it up after it had been sitting after a run, then this could be normal. after a high rev run, tons of oil pools in the heads because the scavenger pumps cant keep up and pump the oil out, then at the next start up, it smokes. The solution is to let the car idle for a few minutes after a run so the scavenger pumps can clear the heads.
10-13-2014, 05:09 PM
#10
Rennlist Member
Thread Starter
A month ago I was at an autocross and had similar. (also an '03 996)
First run, no smoke. Then, the car sat for maybe an hour until the next run. Huge cloud of white smoke that looked like a NASA liftoff. Smoked much of the run, but at a relatively low volume. By the end of the run, the smoke had stopped.
Also, it's never done that before (smoked) at either the track or at an autocross. Odd.
First run, no smoke. Then, the car sat for maybe an hour until the next run. Huge cloud of white smoke that looked like a NASA liftoff. Smoked much of the run, but at a relatively low volume. By the end of the run, the smoke had stopped.
Also, it's never done that before (smoked) at either the track or at an autocross. Odd.
After everything JR has posted about tracking an unmodified M96, why are you doing it? I bet you even had the wrong oil in it too. Your lucky your car left the track intact (if it still is). Oil starvation and AOS/OVS issues for the stock M96 are no joke. Consider yourself warned for next time?
Tell me more about this????
10-13-2014, 05:11 PM
#11
Rennlist Member
Thread Starter
Reads like the AOS got overwhelmed and gave the engine a good shot of oil. Probably wet the heck out of the intake manifold with oil which is why the smoking persisted.
Absent any signs the engine is not running right, and as long as the smoking doesn't return, that's what I would hazard a guess is what happened.
Be sure you check the oil level. I think you'll find it low.
Be sure when you attend another AX event you show up with the engine full -- but not overfull -- of fresh oil.
While I can't be sure I suspect the smoking episode was possibly partially due to oil that should have been changed before the event. While 1500 miles is not that many miles on oil depending upon how the car is used oil can still end up quite contaminated with unburned fuel and water (combustion byproducts) and these can have the oil more prone to foaming and thus creating more oil vapor in the engine which can overwhelm the AOS and the smoking was the result.
Absent any signs the engine is not running right, and as long as the smoking doesn't return, that's what I would hazard a guess is what happened.
Be sure you check the oil level. I think you'll find it low.
Be sure when you attend another AX event you show up with the engine full -- but not overfull -- of fresh oil.
While I can't be sure I suspect the smoking episode was possibly partially due to oil that should have been changed before the event. While 1500 miles is not that many miles on oil depending upon how the car is used oil can still end up quite contaminated with unburned fuel and water (combustion byproducts) and these can have the oil more prone to foaming and thus creating more oil vapor in the engine which can overwhelm the AOS and the smoking was the result.
10-13-2014, 05:50 PM
#12
IMO for any serious track work, you should have X51 pan, Motorsports AOS, and either the Accusump or the X51 dual scavenging pump mod as to not starve your engine in long hard sweepers, especially if you are running good suspension and R compound tires.
Non x51 engines are only fitted with one oil scavenging pump on one side. The X51 motors are fitted with two on each side. It doesn't guarantee you won't have oil starvation but definitely reduces the chances of it. If you are paranoid, supplement it with the Accusump as well.
Non x51 engines are only fitted with one oil scavenging pump on one side. The X51 motors are fitted with two on each side. It doesn't guarantee you won't have oil starvation but definitely reduces the chances of it. If you are paranoid, supplement it with the Accusump as well.
10-13-2014, 06:49 PM
#13
Race Director
Whether it does a better job of separating the oil from the (crankcase) air I can't say. My WAG is probably not. I say this based on the assumption it is probably the same basic design as the stock AOS and thus shares its inefficiencies.
At the risk of being accused of being wise after the fact, my opinion is the AOS is not really the problem -- as long as it is healthy -- it is the oiling system of the engine, and more specifically the oil scavenging system of the engine.
As alpine003 covered very well there are mods that improve the oiling of the engine and just as importantly the oil scavenging.
Were I preparing a car for track usage I'd do the oiling/oil scavenging mod's first. Then perhaps add the motorsport AOS if the stock one failed too often. IIRC the motorsport version runs around $900 (and can require extra work to install) while the stock unit can be had for around $120 and while the installation may not be a piece of cake easy it is easier than the motorsport AOS installation.
10-13-2014, 07:07 PM
#14
Race Director
In case anyone's wondering, an autocross is not typically considered a track event. Autocrosses are generally tight courses that accentuate smoothness and precision, not high-speed. This is why Miatas and 914's tear up Corvettes and Turbos. Autocross is also one of the few driving events you can participate in with a totally stock car.
Oil system upgrades should definitely be considered when you're upgrading from street tires and stock suspension to racing slicks and adjustable suspension components. If you want to spend the money upgrading your oil delivery system on a bone-stock car, that's your prerogative, but to me it makes about as much sense as the giant red tow hooks you see screwed into Honda Accord bumpers all across America.
Oil system upgrades should definitely be considered when you're upgrading from street tires and stock suspension to racing slicks and adjustable suspension components. If you want to spend the money upgrading your oil delivery system on a bone-stock car, that's your prerogative, but to me it makes about as much sense as the giant red tow hooks you see screwed into Honda Accord bumpers all across America.
10-13-2014, 07:32 PM
#15
Track events generally can experience longer/higher/sustained g levels however both auto-x and track events can both see high sustained rpm's during your whole run. This is more of what's at play here.