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Oil in 924 turbo intake.

 
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Mreed1  



Joined: 22 Sep 2014
Posts: 12
Location: Altoona, IA

PostPosted: Thu Aug 11, 2016 12:58 pm    Post subject: Oil in 924 turbo intake. Reply with quote

I have 1980 924 turbo in which I just had the turo rebuilt. I'm getting oil in the intake and it smokes while running. It's hard to start the engine while cold. Sometimes that will run well for a long period of time and then have a warm hard start problem. Any suggestions?
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macBdog  



Joined: 16 Aug 2004
Posts: 1098
Location: Brisbane, Australia

PostPosted: Thu Aug 11, 2016 1:16 pm    Post subject: Reply with quote

Classic aging 931 issues right here, you've come to the right place. Plenty of other members will have a crack at diagnosis but to kick it off in reverse order...

Warm engine hard start: Check the fuel accumulator at the rear of car near the gearbox.
Cold engine hard start: Check cold start valve and WUR
Smoking out the tailpipe after turbo rebuild? Leakdown test, oil getting past rings and into intake.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1534
Location: Not Detriot - NMI

PostPosted: Thu Aug 11, 2016 1:22 pm    Post subject: Reply with quote

Sounds like multiple separate problems..

Look for vacuum leaks and fix them all, if you are planning to keep the car just replace all the rubber vacuum elbows and hoses..

Do a CIS test, you will have to get or make a CIS tester..


As far as the oil in the intake, that sucks.. You could maybe try running it in for a little longer hoping the intake side piston rings on the turbo seat themselves, or make em rebuild it again.. idk

iirc it is not unheard of for a freshly rebuilt turbo to leak oil like that..
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ideola  



Joined: 01 Oct 2004
Posts: 15493
Location: Woodstock IL

PostPosted: Thu Aug 11, 2016 3:05 pm    Post subject: Reply with quote

Smoking while running may have nothing to do with the turbo. It could very likely be worn valve stem seals (moderate difficulty to replace, can be done with engine in situ) or worn/broken piston rings (best to pull the motor for this one).

Difficult warm start: for an engine that has been fully warmed up and running within the last hour or so, the owners manual calls for depressing the accelerator all the way to the floor, and then starting. You may find that this solves the hot start problem. If it doesn't, it's best to get a CIS tester and go through this regimen to isolate the problem. The accumulators are frequent culprits, but there could be multiple compounding problems, so best to be highly methodical when troubleshooting the CIS.

Difficult cold start: can be caused by any number of the CIS components: failed cold start valve (CSV), failed thermo-time switch (TTS; tells the CSV when and how long to spray), failed wiring between TTS and CSV, failed or stuck auxiliary air valve (AAV), failed warm-up regulator (WUR), etc. For general troubleshooting, follow the regimen here, which covers most of these issues and more.

Welcome to the forum. Keep the questions coming, I'm sure the crew here can help you get it running reliably!
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1545
Location: Somerset, UK

PostPosted: Thu Aug 11, 2016 6:58 pm    Post subject: Reply with quote

Put a bore scope in the spark plug holes when cold and see if there is wet oil pooling in the Pistons. This would indicate valve stem oil seals leaking. This is indicated by oil smoke on start up but gone once warmed.

Compression test to see if the bores/rings are worn. Results should be within 10% of each other. Piston #3 and #4 are usually the culprits of bust rings. Worn or snapped rings with cause oil smoke at all times especially on revving and under load.

These engines do breath oil vapour. The design of the breathing system draws positive pressure in the crankcase through the Purolator and turbo and into the intake manifold. Even a good engine will have oil mist in the system. A bad engine will have oil pooling in various spots.
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macBdog  



Joined: 16 Aug 2004
Posts: 1098
Location: Brisbane, Australia

PostPosted: Thu Aug 11, 2016 7:41 pm    Post subject: Reply with quote

Great replies, remember you can get a borescope that connects to your mobile phone off ebay for like $5! Check it out:

http://www.ebay.com.au/itm/5-5mm-7mm-Android-Phone-Endoscope-IP67-Inspection-Borescope-HD-LED-Camera-video-/152154628407?var=&hash=item236d1f6137:m:mHgBPZLtMEQXG_gid4kXHMg
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1979 931 with a 350 chev
1973 911E with EFI
p-talk wrote:
I'm still convinced the word 'Porsche' makes people crazy in all kinds of ways
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11353
Location: PacNW

PostPosted: Fri Aug 12, 2016 3:05 am    Post subject: Reply with quote

Rebuilt turbo on a worn motor will smoke due to crankcase pressure interfering with turbo oil drainage. This is bad for the turbo, as are the combustion gasses in the crankcase. Ask me how I know!

2nd the broken ring hypothesis.
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Mreed1  



Joined: 22 Sep 2014
Posts: 12
Location: Altoona, IA

PostPosted: Sat Feb 18, 2017 11:52 pm    Post subject: Oil in 924 turbo intake. Reply with quote

Checked the compression and all around 120 psi. Still have oil in intake and plug fouling after run up. Could thr seals on the rebuilt turbo be leaking?
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ideola  



Joined: 01 Oct 2004
Posts: 15493
Location: Woodstock IL

PostPosted: Sun Feb 19, 2017 12:32 am    Post subject: Reply with quote

You need to do a leakdown test on the cylinders, as the compression test only gives you a moment-in-time reading. The leakdown test will tell you if air is bypassing the rings. 120PSI sounds low to me.
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11353
Location: PacNW

PostPosted: Sun Feb 19, 2017 2:57 am    Post subject: Reply with quote

14.7 x 7.5 = 110.25

120 sounds fine to me.
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Paul  



Joined: 02 Nov 2002
Posts: 9312
Location: Southeast Wisconsin

PostPosted: Tue Feb 21, 2017 10:45 am    Post subject: Reply with quote

I remember a case where a 931 had the wrong dipstick and was overfilled with oil.....
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