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Ron Henderson · Joined: 06 Jan 2009 Posts: 21 Location: San Clemente, CA

Our freshly rebuilt 931 is smoking---blue smoke (oil)... The compression is great at 140 to 150 psi (8.5:1 pistons) and the turbo was completely rebuilt. The motor is new top and bottom and no oil has appeared on the walls of the charge tube. Also---it does not appear to have any blow in the crankcase ventilator hose.

Any ideas about what is causing puffs of blue smoke when the car is revved up. We ran it for an hour and we are still having problems.....now the turbo is on the bench and the expert says it is perfect!!

Thanks!

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Ron Henderson
Kaman Industrial Technologies

951-312-1625 cell

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

How are the valve guides/valve stem seals?

Headgasket? Don't necessarily need to have oil and water mixing to have a leaking headgasket.

Do you have access to a leakdown tester? That might hint at where the leak could be coming from.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

The plugs should also be indicative...if there's oil fouling on the plugs, it's either rings or valve stem seals.
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erstwhile owner of just about every 924 variant ever made

Smoothie · Posted: Tue Mar 16, 2010 9:18 am Post subject:

Did it get a proper break-in before the worrying started?
I'm pretty sure it's not unusual to get some oil smoke early on after a rebuild/overhaul. How much smoke are we talking? Just enough to see? - or a little more? - or huge embarrasing clouds of it?
We've a few threads here on correct ring break-in.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Joes924Racer · Posted: Tue Mar 16, 2010 10:20 am Post subject:

Just guessin. Hows the air-fuel mix.
My Na will kind a do that if its to rich.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

Ron Henderson · Joined: 06 Jan 2009 Posts: 21 Location: San Clemente, CA

There was huge embarrasing clouds of it. The car has never left the driveway, however it ran for an hour in neutral. It has brand new JE with their rings. New valves seals. Turbo completely overhauled. This one's weird.

Thanks!
_________________
Ron Henderson
Kaman Industrial Technologies

951-312-1625 cell

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Did you follow a break in procedure?
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

emoore924 · Joined: 13 Apr 2004 Posts: 2822

Crankcase ventilation...?

Did you block off the air/oil separator?

macBdog · Posted: Tue Mar 16, 2010 2:07 pm Post subject:

I have had this problem from oil not draining out of the turbo fast enough. Had to install a scavenge pump.
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1979 931 with a 350 chev
1973 911E with EFI

Cedric · Joined: 27 Aug 2004 Posts: 2822 Location: Sweden

Had the exact same problem this summer. Newly rebuilt turbo, nice compression and loads of blue smoke. The car didnt smoke on the first test starts but then it just started during a test drive. Tried everything, no clogged vent lines, no glogged oil lines, all was perfect. One day the problem just dissapered. After that the car didnt drink any oil under the season. Just some short puff when it has sat for a long time. Really weird..
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1980 924 Turbo
www.instagram.com/garagecedric/

Ron Henderson · Joined: 06 Jan 2009 Posts: 21 Location: San Clemente, CA

the lines are all free flowing----we blew right into the PVC hose at the air cleaner and at the separator---no restrictions. The oil drain lines are all free flowing with no restrictions. No blow by oil was detected in the PVC system--clean as a whistle. Last time at start up we had no smoke until it was revved up a bit.

The car has not been on the road yet with only driveway time---so I'd say we did not start the break in period...yet

At those point we are going with trail in error
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Ron Henderson
Kaman Industrial Technologies

951-312-1625 cell

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Sounds to me like the rings have not bedded in.
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erstwhile owner of just about every 924 variant ever made

Fifty50Plus · Posted: Wed Mar 17, 2010 6:54 am Post subject:

Break in on driveway: 2500 - 3000 RPM no load for 30 minutes. See if smoke is reduced. A really hard ring (Swedish steel) and strange wall hone will take a long time to begin sealing. Improper hone is usually the culprit for poor sealing.
Chuck
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1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

Joes924Racer · Posted: Wed Mar 17, 2010 8:39 am Post subject:

Yea sounds like the rings havent dsealed all the way letting oil get by to seal. Did you hone the block yourself. May be you need tio drive it under load to get it sealed ..broke-in... and your sure its not the fuel air mix at all cuase you probly didnt mess with that at all. I might want to lean it out a little counter clockwise on the adjuster to see if that helps.. then
just drive it.
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

Ron Henderson · Joined: 06 Jan 2009 Posts: 21 Location: San Clemente, CA

I think everything is going to go back together and I'm going to try the method provided by Fifty50Plus (Thanks!). Block was professionally honed by local shop and tuning was done by Bill Brewster San Clemente. We are going to have to break it in on the driveway as there are no seats in the car and registered non-op.

Many Thanks!

*edit: I'm going to attempt to break it in on the driveway as provided in Fifty50Plus's instructions, I don't know if it is possible.
_________________
Ron Henderson
Kaman Industrial Technologies

951-312-1625 cell