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YOUR RESEARCHHelp! white smoke after spirited driving......
Reported or suspected cause
oil crossing the intake manifold
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Reported cause
I've had my car smoke after start-up after hard runs in the canyon and at the track -- but this is due to the oil crossing the intake manifold.
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Performed · outcome unconfirmed · Original poster
Checked the oil again after this white smoke today and I am two bars low.
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Performed · outcome unconfirmed · Original poster
Oil was changed 2 months ago and I have only put about 500 miles on the car since.
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Outcome without a verified action link
The lastest generation of coolant cap fixed the problem.
last time I drove my 2002 996 C4S was about two days ago. Not a daily driver but gets driven 2 or 3 time a week, about 5k miles a year. Car has 66k miles, owned for the last 4 years (never had any problems).
Drove the car for about 20 spirited minutes at lunch time, a couple of redline shifts, one slight over rev in first gear, first time I ever did that (about 300 rpm past redline). shut it off hot, went back in the office.
came out an hour later, started the car and their was a HUGE cloud of White Smoke on start up. Lasted about 10 seconds, maybe less. Lasted about as long as it took me to notice the smoke, unbuckle seat belt and walk to the exhaust pipes.
Smoke from exhaust pipes looked white not blue.
drove it about 5 minutes, ran fine no smoke. parked it. Started it an hour later, another HUGE white cloud of smooke for about 3 seconds. Shut off car.
waited half hour, started again, white smoke for 2 seconds.
Never had this cloud of smoke happen before. This is not a daily driver but when I've gone a week or so without driving, some times a get a tiny puff of white smoke for a second (condensation) but never like this.
Outside temps were 90 degress and very humid. Water temp was normal. Last oil change was 2 months and 500 miles ago. I did about 2 months ago top off the oil (added a half qrt) for an autocross.
Oil had been full and was full last time I check probably a few weeks/a month ago.
Checked the oil again after this white smoke today and I am two bars low.
Anyone know what this might be?
thank you,
G
Couple of things to check quickly. Is there any trace of coolant in the oil, or oil in the coolant. Look in the coolant reservoir and on the dip stick. If you have contamination this would indicate you might have coolant getting into the cylinders.
Next take off the air box and the throttle body and look for oil in the intake plenum. If the AOS is going bad, and this can be a source of such smoke, you will likely see some oil in the plenum. You can also check the breather tube that runs from the AOS to the plenum, it connects to the plenum on the left side behind the throttle body.
Probably a bad AOS.
Sounds like the AOS. I've described the same thing to my indie and that's what he says. Happens sometimes with some spirited driving on the street and about 30-50% of the time after starting up after a DE session.
Hope to hell it's the AOS.
It could be the cheapest thing to repair along these lines. Also hope it's white smoke from burning oil and not steam from coolant leaking into the combustion chamber thru a cracked cylinder liner. This happens all too often and usually ends in a motor replacement.
I wouldn't fret at this point especially if your oil is low and coolant is full. Hoping for the best!
you mean we should drive these cars as if they were made out of fine porcelain?
I don't think i've driven the car in a method OTHER than describing as spirited driving; on and off the track.
Dude hitting the red line a couple of times is not smart. After all its how many years old???? It's your car enjoy it the way you see fit, doesn't sound like this is turning out to be much fun. I have one of these cars to and bought one new in 1999. If you're hitting the red line you are driving pretty fast on the street, thats not to smart.
"Hitting the red line" is the best part of owning that car. I do it at least few times each day I drive it. My car is 8 yrs old and I will rev it to the red line when its 18 years old if I'll still own it. It is good for the car and it is good for me.
You will also get this if your oil is overfilled. It sound like the period of the smoking upon start up is getting shorter and shorter. Keep driving it daily for the next several days and see if it goes away. You said there is no sign of coolant in the oil..
You can do a oil test at Blackstone Labs to check for coolant in the oil.
Every car is different but my 996 coolant expansion tank is always under the min mark. If I add water or coolant it goes back down to the same level after a day and stays there. So I am just saying if you had a coolant leak it would be going down quick and blowing white smoke while driving and idling not just at startup.
I believe your problem is the AOS. Mine has been acting up for over a year and half and it started to gradually get worse, just recently the breather tube is showing oil and oil consumption is really high. AOS can go fast or it can take forever to go.
To azrob226
My car is 8 years old 108k km on it and I hit redline a few times every day and at every shift while at the track in which I have 6 years on tracking it with about 16-20 track days a year. These cars were built and tested to drive at redline without doing damage to the engine. You can baby your if you like but your missing out on what these cars were built to do.
Guys, the redline on these cars is set conservative and the car also has a rev limiter to prevent you from reving it into an unsafe area. You should not rev it beyond 4K until fully warmed up, once there you could probably rev it to the point of hitting the rev limiter nearly every shift without doing damage to the motor. These motors were designed to sing and again 7k is not an RPM that should be high enough to damage them.
Usually the RPM ceiling is set by the reciprotating mass of the piston. Pistons only like to travel so fast, stop, change direction, stop, etc. How far a piston travels is determined by the stroke of the crankshaft. Light weight pistons with a short stroke = high rpm, as strokes increase, PRMs decrease, same with piston weight increases.
Finally, type ll revs, are I believe what Porsche refers to as, the type from down shifting into too low of a gear, where the revs will exceed the ceiling set by the electronic rev limiter. This forces the motor into reving beyond its designed parameters. This can be dangerous and damaging and should be avoided at all costs.
Mine is always just below the minimum. Just like you, i've added water and it eventually goes back to just below.
Drove the car to work today, one second of smoke upon start up and it drove perfectly fine, no smoke while driving.
I just dropped my car off at my local Indy so we'll see.
glad I stopped in here -
hitting the redline or close to it is the best way to keep these motors alive! putting around like a Buick grandpamobile will surely cost you much more in headaches later...
My 996 has 120k miles on the clock and when I drove it (properly warmed) it saw near redline everyday. I often drove to work in 3rd or 4th and kept the rpm above 4k all the way...the new owner is driving it everyday the same way. That said we have a small issue with a cam solenoid right now... but that motor is smiling happy.
I recently helped do a complete rebuild on a Tip car that suffered a catistophic failure and the insides of that car made it obvioous the car lugged around and was never properly driven (carbon all over the place) The owner claiming, I never drive it hard, dont know why it died...well thats the reason.
for what its worth your engine saw redline at the factory and again when it was installed and on its maiden voyage around the test track... there is not "take it easy on the motor till it breaks in"... they drove the **** out of it right out of the gate.
There is a major differance between driving it spiritedly and beating the car (by the way its tough to beat these cars, and mainly comes down to warm up, cool down and propper maintenance)
so all you out there afraid to push the gas... imagine puushing it so hard that it would not go any further....now repeat again and again after you propperly warm the car... and drive it a while to cool it down... if it smells when you park it.... that was a good day for your car. There is a very special smell it should have...go to the track and you will discover it, then make sure yours smells like that damn near everyday - FWIW I hit redline or near everyday on my 86' and it has 170k miles on the clock.....
+1 for AOS by the way (back on topic)
if the car is driven on short trips and the oil hasnt been recently changed your car will absorb water in the motor and what you saw was that water being burned out of the oil after being caught by the AOS... my advise is to drive it again and again in the same way and see it it repeats (providing you dont put it away hot as you did before.... do a little cool down lap)
its normal to have the coolant be a little low if you have not checked it in a while as over time air bubble escape... fill it to just below propper level and watch it. and for the oil, yes.... a little low is way better than a tiny over.
its my opinion you should drive it.....watch for a repeat - THEN change (check) for an AOS problem
I've had my car smoke after start-up after hard runs in the canyon and at the track -- but this is due to the oil crossing the intake manifold.
I wonder if anyone has put an oil catch tank on these motors? I had a similar problem with my S2000 and the oil catch tank alleviated the "non-issue"
I had my 02 C2 for a month now and the same thing happened 2 weeks ago after a long spirited drive - I called the dealer next morning as this car is under CPO warranty and he told me it is gas build up on the intake manifold and he has seen that a lot - he suggested to let the car idle for a minute after a spirited drive - this issue lasted 3-4 starts and about 1 day and never happened again
hope that helps
Oil was changed 2 months ago and I have only put about 500 miles on the car since. It has been used for very short trips the last two months and I did not let the car cool down after the spirited drive.
Oil could have been a tad high, I topped it off (add a 1/2 qrt) before doing an autocross back in May. I check it this morning and it read 2 bars low. Coolant was slightly below minimum and that's normal. When I top it off it typically goes back to slightly below minimum in a few days.
I drove it this morning to my local indy (short trip) and there was just white smoke for a second upon start up.
I will probably have the AOS replaced as a precautionary measure.
I love this car and want to keep it forever so I hope its a simple problem. This is the second longest I've kept a car. I've had about 20 cars in the last 20 years so I must really like it.
P.S. my car is a 6 speed, don't think I said that above.
Not normal for a car to lose coolant, for the level to drop. I suspect the car's coolant cap leaking. Do yourself a favor and if cap does not have part number that ends in 03 or 04 buy a new cap and fit it.
Both my 02 Boxster's original coolant cap developed a leak -- and I replaced it -- and I spotted the symptoms with my 03 Turbo and had it checked and sure enough the cap would not hold pressure and cap was replaced (car under CPO warranty).
Sincerely,
Macster.
+1 for DDun911, my 996 used to do it almost everytime I restarted after a moderately hot track session. Did it for 3 years and never gave me any further trouble
+1.... this is normal, if it burns out within several seconds. Its common for boxer engines to behave this way... inherent in their design. Though not all does it.
Same thing happened to me on my first track day. Had a pretty quick session, shut down car. An hour later start the car again - huge puff of white smoke. I was freaked out. Then, an hour later, saw a 996 GT3 do the same thing. Then, saw a 993TT do the same thing. Called a friend who has raced 911s and Caymans for more than a few years in Grand Am (well, Koni/Conti) - they all do that. Says he underfills the oil a little just for that reason. Seems like, due to the boxer design, and different parts cooling at different rates, some oil can leak past the piston seals.
M96 motors need vacumn in the case to alleviate foaming. Venting to a catch can eliminates that vacumn. I was told by a Grand Am motor builder it would destroy the motor....
From my experience, just running the car hard will not cause smoking on startup, but pulling significant later g's will. I always keep my car about 1/2 qt low to the full mark, and that alleviates the problem. So... if you were doing some significant cornering, I would just make sure to run 1/2 qt low to full, and not worry. If on the other hand the driving involved just running the engine hard... I'd look to other issues.
I think you are correct. My Indy checked the car and said there is abosutely nothing wrong (it doesn't smoke on start up any more) He said the oil was slightly overfilled and this is what caused the problem if I took some high G turns.
I have never done a DE with this car but there are some great driving roads where I live and work and I did take some fast high G turns just before getting back to work and shutting the car off hot. (Car smoked on the next start up).
I'm glad to know that this is normal, next time I will let the car idle and cool down before I turn it off and never overfill the oil.
my advise is to take your sprited driving off public roads and save yourself the potential for more than you bargined for...
just saying, be safe.........
most states are low on money and have extra patrols out hunting for revenue. I scored a wopper a couple months ago. Seems the track days get it out of my system and I tend to drive on the public roads a lot less spirited.
There's nothing wrong with your car. As DDun911 noted, you should just let the car idle for, say, 5 minutes after intense driving. The first (and only) time my car did this at the track, I almost had a code brown, but there were plenty of people around to tell me the remedy. It's never done it since.
I agree with you 100%. I did not exceed the speed limit once (really). My high rmp shifts were in first gear which doesn't exceed 50 mph speed limits. I have never received a speeding ticket in my 23 years of driving, and I've only driven fast sports cars.
I've never DE the porsche but I've done about 100 DE's and autocrosses in the last 10 years in both several M3's and Z06's including 5 skip barber racing schools
These were curvy roads with no traffic, and sharp entry and exit ramps. But yes cops are everywhere in New Jersey.
I agree you're right I will do that from now on.
I got the car back today and it drives 100% normal, no smoke, nothing.
glad there is a happy ending, I love this car
