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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHBlue smoke when driving
Reported or suspected cause
air oil separator
Reported cause
No successful repair reported for this finding.
1
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0
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0
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Reported cause
I explored the AOS option, my AOS was also new but I had a lot of guidance telling me it was the AOS.
Leading evidence: 'air oil separator' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'air oil separator' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check bore scoring and all ok' (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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Performed · outcome unconfirmed
The fault was traced to worn valve seats, these were changed and all is now well.
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Suggestion · Original poster
I should add it has had a new Aos 12mths ago and had the bore pressures checked for bore scoring and all OK.
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9 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Porsche Club GB: 1 discussions
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Hi. I'm sure this has been discussed before. 996's and Blue smoke! The whole blue smoke on start up occasionally happening is something I've come to live with. However! On four occasions in total since owning the car (12 months), two of which happened today on the way to and from Chatsworth, I have had a puff of blue smoke come out whilst I'm driving. It doesn't last long and looks to be from both exhausts. Oil pressure stays fine and no other warning lights. Once it clears all is good and no more smoke! I should add it has had a new Aos 12mths ago and had the bore pressures checked for bore scoring and all OK. Anybody any thoughts as I'm biting my nails just waiting for the thing to blow up!
Thanks in advance.
Hi
It was good to speak to you at Chatsworth yesterday. When you said that you'd had the cylinder pressures checked and that they were ok did you mean that the pressures were all similar or that they were verified as being within tolerance?
Hope you manage to get this sorted without too much expense!
Simon
I have read elsewhere oil overfill can cause this - if you can draw some off/drain it out, get it between half and full on the dipstick (no matter what the current reading appears) then run it every day for at least 15 mins for 3-5 days, even just idlin (it can take time for the effect to clear). Sounds obvious, but it might just do the trick. Good luck.
Unlikely Geoff.
This is what a failed AOS looks like - white-ish smoke:
https://www.youtube.com/watch?v=txr6jXTKz2c
And Andrew says that the AOS was replaced in the last 12 months, so unlikely to be the cause of the problem. He mentions blue smoke, which means the engine is burning oil. If the oil level is correct and the bores are OK then, depending upon mileage, maybe it's worn valve stems/seals, although that should have been flagged up by the cylinder compression test.
Puzzling.!
Jeff
I had similar when I got my 996 in February (there is a thread on my blue smoke dated March 2017).
I only noticed the smoke on start up (after a layup for a few days), I don't know if it was smoking while running.
I explored the AOS option, my AOS was also new but I had a lot of guidance telling me it was the AOS. My mechanic said new AOSs hardly ever fail, but by coincidence he had just had a new one fail and was actually changing it when I saw him.
I had a bore scope inspection done and all was well.
The fault was traced to worn valve seats, these were changed and all is now well.
I don't know how much the work cost as the engine is covered by a warrantee (it had IMS bearing failure and piston damage late last year so it was rebuilt). Since the valve work I haven't done enough miles to monitor oil usage, but it seems to be well within the maximum tolerance.
I don't know if that helps you or not!
