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YOUR RESEARCHWhite smoke screen from exhaust
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Check before it takes your motor out
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Leading evidence: 'Check before it takes your motor out' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check before it takes your motor out' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Regarding oil, I run 0w30....you can run what you like as long as your engine achives approx.
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You need to have your engine cylinders pressure tested, particularly cyclinders 5 and 6.
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Suggestion
Have you checked the crankcase vacuum with a manometer to rule out a bad AOS?
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Suggestion
3) You lose 1.25 quarts of oil every 7000 miles - meaning you check your oil level and add oil every 7000 miles?
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2002 996 c4 I have search other trheads and not found one like my issue. I did not run the car hard and as I turned into my neighborhood thick white smoke came bellowing out the exhaust and rear. Car also ran rough and I thought it was going to seize up. I pulled over and noticed coolant was low. I have had an intermittent leak for a couple months. I topped it off(about a QUART). Started it up and more thick smoke with little to no odor. So thick that it completely hid the world from view in seconds. It appears to be water vapor. There is no mix in the oil or oil in the coolant. No trouble codes other than PO 0455 for loose gas cap. What gives here?
I forgot to mention that the oil light came on briefly and when checked it was 1.25 Quarts low but Mobil 1 seems to evaporate a quart every 7000 miles in whatever I run it in. 10w30
"I have had an intermittent leak for a couple months. I topped it off(about a QUART). Started it up and more thick smoke with little to no odor. So thick that it completely hid the world from view in seconds. It appears to be water vapor. There is no mix in the oil or oil in the coolant. No trouble codes other than PO 0455 for loose gas cap. What gives here?
when checked it was 1.25 Quarts low but Mobil 1 seems to evaporate a quart every 7000 miles in whatever I run it in. 10w30"
1) You have an intermittent coolant leak for a couple of months - and did nothing about it.
2) You have a CEL for your gas cap - and did nothing about it.
3) You lose 1.25 quarts of oil every 7000 miles - meaning you check your oil level and add oil every 7000 miles? Hmmm...
You need to have your engine cylinders pressure tested, particularly cyclinders 5 and 6. Hopefully it is just a cracked head. Hoffmans can fix it up for you.
NOT turning this into oil discussion but 10w30 IS NOT the correct weight to be running in these engines. 5w40 is your best bet with some heavier weights possibly, depending on several factors.
Needed to read your post again...
Where exactly is it coming out? If a cracked cylinder liner (and I did have coolant in the oil fwiw), water vapor would be coming out of one tailpipe (assuming you don't have an x-pipe setup). If its coming out the whole engine bay, you're probably looking at a cracked coolant tank or ruptured hose, but that wouldn't explain the rough running. As others have mentioned, pressure testing the cylinder and cooling system is a good start.
Blowing the engine could mean a lot things, but a cracked liner would required a full rebuild. At least you'd be at a better starting point.
https://rennlist.com/forums/996-foru...s-rebuild.html
No idea until you've figured out the issue. Here's a good thread for rebuild costs:
https://rennlist.com/forums/996-foru...under-10k.html
The numbers will be much higher if you're not supplying the labor. Best case scenario its just the coolant tank or a hose.
1. I had a mechanic try to find the leak but he did not. I did keep it topped off as needed
2. I replace gas cap but code still pops up from time to time
3. I keep tabs on the oil. All I was saying was that in every vehicle I own, running Mobil 1, loses some oil around 6-7000 miles.
I tried 0w40 and 5w40 in my 2001. It didn't like them, noisy motor and I went back to 5w30 which was suggested by Porsche, And everything quieted down.
OK, finally got some free time to look at it. Its definitely coming out of the exhaust and smells a little like oil. It cleared up by itself and then returned on its own. I did get another code today. P0134 O2 sensor B1S1 no reading. No coolant leaks or any other leaks. Still no mix of fluids. I have a short video I will post if I can. Also, the smoke is way more prevalent on the right hand side. I guess its off to the shop?!
Normally, when someone complains about excessive smoking out the tailpipe on a Porsche 996, my immediate reaction is a failing AOS. IMHO, you need to rule that out.
You Tube
You Tube
Official product number for 2002 996 3.6L C4 it is that 99610702651 but without M100. Pelicanparts adds their own identifier. Just make sure that you get a genuine part - it's not that expensive.
Or then that "Rennlist product" called UAOS ->
https://ultimateaos.com/
Look for threads here.
Brianbbs67, take off the airbox+hose, push open the throttle valve with your finger and check if the intake behind it is oily. It should be dry, if not the oil comes via the PCV(positive crankcase ventialtion) system which has the famous AOS(Air Oil Separator) in it. The smoke thickness you describe tells me it is oil burning and not water evaporating.
Causes could be broken AOS and/or scavenge pumps dead/very worn in conjunction with leaky chain tensioners. Possibly a combination of it all. Heavily overfilling with oil could also generate the same smoke screen.
Regarding oil, I run 0w30....you can run what you like as long as your engine achives approx. 3.5bar @ 5k rpm. Idle oil pressure is rather irrelevant but anything over zero is good.
Thanks, Checkered Flag Porsche verified its correct and Yes, only Porsche Parts for this one.
Yes it is oily. I'm leaning AOS. As pressures and engine running conditions are good. (I am not running it now of course). Hopefully, I dodged a bullet. I ordered a Porsche AOS today for $120 and will have the local shop look at it and relay the findings.
In another year or so, take a hard look at replacing the Oem aos with a UAOS or Motorsports aos.
The Uaos allows you you change the diaphram without removing the aos plus it has additional enhancement parts that can be added for the track. This will save time and money.
The motorsports aos will have to be removed and replaced.
Both are durable as he'll in relation to the Oem aos. Unfortunately, the Oem aos has a very short life span.
Hi Brian
As mentioned by others, white smoke is usually coolant and will tend to dissipate whereas oil, bluish in color will hang in the air. I would see if you can get a hold of a slack tube manometer and verify the crankcase pressure as it is possible your AOS has failed and you now have higher vacuum going to the crankcase and pulling up oil. Use an Airlift kit for the cooling system, this kit will apply 25" vacuum to the cooling system and generally if you have a leak, it will not be able to draw down a vacuum on the cooling system. I measured my 2003 996 crankcase pressure today at the dipstick and it was 6" H2O.
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