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[Video] Bad smoking problem
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macBdog  



Joined: 16 Aug 2004
Posts: 1111
Location: Brisbane, Australia

PostPosted: Mon Jan 07, 2008 9:45 am    Post subject: [Video] Bad smoking problem Reply with quote

http://www.youtube.com/watch?v=KGjl6Q3zDPY

A few weeks ago my car started smoking on start up a little bit. As soon as it came up to operating temperature there were no problems. But its slowly been getting worse and worse, now its how it is in the video.

My initial thought is busted turbo passing all the lubricating oil straight into the exhaust. When I was writing my fuel map it backfired many times which can't be good for the turbs. What do you guys think?
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Rasta Monsta  



Joined: 12 Jul 2006
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Location: PacNW

PostPosted: Mon Jan 07, 2008 9:57 am    Post subject: Reply with quote

The turbo can also leak into the intake. Was it backfiring thru intake or exhaust?



AIEEEE!
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simsport  



Joined: 06 Nov 2002
Posts: 573
Location: UK Warrington

PostPosted: Mon Jan 07, 2008 10:34 am    Post subject: Eek! Reply with quote

Shame its let go, sounds a bit noisey too.

I would do the basics, comp and leakdpwn test first as it could be a head gasket and/or piston ring/valve due to det.

Cheers and good luck!

Simon,
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Lizard  



Joined: 03 Nov 2002
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Location: Abbotsford BC. Canada

PostPosted: Mon Jan 07, 2008 11:15 am    Post subject: Reply with quote

wow what a face haha.

I agree with Simon, do a compression and leakdown test first.

also look in the intake tubing, is there a coating of oil all over the intake? if there is then the seals in the turbo could be shot, but do a compression and leakdown test first.
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Min  



Joined: 04 Nov 2002
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Location: Vernon, British Columbia, Canada

PostPosted: Mon Jan 07, 2008 11:39 am    Post subject: Reply with quote

you've got a different turbo on there from stock right? ... whats the oil pressure going into the turbo?

Min
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macBdog  



Joined: 16 Aug 2004
Posts: 1111
Location: Brisbane, Australia

PostPosted: Mon Jan 07, 2008 11:59 am    Post subject: Reply with quote

Min wrote:
you've got a different turbo on there from stock right? ... whats the oil pressure going into the turbo?


Yea its a ballbearing garrett. I wish I had a way to measure the oil pressure but I have restricted the flow heaps by making a new banjo bolt:



Since then I've made a bolt with even smaller holes (1mm) because I was still getting too much volume for the turbo. I will check the intake piping and do a leakdown test asap.

Also I doubt its been detonating... the tune is super rich (soots up the plugs in 5 minutes of running) and very low boost.

Thanks for your replies, will get back to you.

Haha also rasta thanks for pointing out my AIEEEE face.
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p-talk wrote:
I'm still convinced the word 'Porsche' makes people crazy in all kinds of ways
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tuurbo  



Joined: 08 Aug 2007
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Location: East Windsor, New Jersey

PostPosted: Mon Jan 07, 2008 1:36 pm    Post subject: Reply with quote

I guess the extra bad news possibility is that if the turbo is leaking oil into the intake, oil can cause detonation easy especially if it is being blown in by a hot turbo, can't it (burn, create carbon, stuff like that?), so...AIEEE. Yeah check everything out.

Or it could be something stupid and fixable - pray to your God(s) for divine mercy.

I'm pretty sure mine blows a bit of oil into the intake too but I'm loathe to rebuild the turbo because I had it rebuilt a couple of years ago - it would fail Lizard's test but I agree it's best to have a look and know what you've got.

Cool plumbing. Looks great.
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Min  



Joined: 04 Nov 2002
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Location: Vernon, British Columbia, Canada

PostPosted: Mon Jan 07, 2008 5:15 pm    Post subject: Reply with quote

Testing the actual oil pressure going into your turbocharger is not a optional step in my opinion. You need to be sure the pressure is within spec.

Min
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morghen  



Joined: 21 Jan 2005
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PostPosted: Tue Jan 08, 2008 2:19 am    Post subject: Reply with quote

Check the plugs...if they are black...you might get oil into the intake.
Then check the turbo seals...they might not seal properly until things heat up. Dunno about the missfire...check your maps...this is why i'm afraid of going EFI. However...the engine sure sounds tappety and noisy.

my 2cent.
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emoore924  



Joined: 13 Apr 2004
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PostPosted: Tue Jan 08, 2008 2:40 pm    Post subject: Reply with quote

I've seen that twice.

Once when one of the valves was leaking oil into the exhaust side of the head. It started out light like that, and got worse, and got worse, until it looked like I was crop dusting. Headwork including new valve seals and bushings solved that.

The second time (and much worse) was when the crankcase was getting overpressurized because I had put a goofy bypass in the oil separator circuit. Forced oil into places I'd never imagined -- including out the tailpipe in great billowing clouds.

Good luck.
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Min  



Joined: 04 Nov 2002
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Location: Vernon, British Columbia, Canada

PostPosted: Tue Jan 08, 2008 4:53 pm    Post subject: Reply with quote

http://www.turbobygarrett.com/turbobygarrett/tech_center/faqs.html

Quote:
# Does my turbo require an oil restrictor?
Oil requirements depend on the turbo's bearing system type. Garrett has two types of bearing systems; traditional journal bearing; and ball bearing.

The journal bearing system in a turbo functions very similarly to the rod or crank bearings in an engine. These bearings require enough oil pressure to keep the components separated by a hydrodynamic film. If the oil pressure is too low, the metal components will come in contact causing premature wear and ultimately failure. If the oil pressure is too high, leakage may occur from the turbocharger seals. With that as background, an oil restrictor is generally not needed for a journal-bearing turbocharger except for those applications with oil-pressure-induced seal leakage. Remember to address all other potential causes of leakage first (e.g., inadequate/improper oil drain out of the turbocharger, excessive crankcase pressure, turbocharger past its useful service life, etc.) and use a restrictor as a last resort. Garrett distributors can tell you the recommended range of acceptable oil pressures for your particular turbo. Restrictor size will always depend on how much oil pressure your engine is generating-there is no single restrictor size suited for all engines.

Ball-bearing turbochargers can benefit from the addition of an oil restrictor, as most engines deliver more pressure than a ball bearing turbo requires. The benefit is seen in improved boost response due to less windage of oil in the bearing. In addition, lower oil flow further reduces the risk of oil leakage compared to journal-bearing turbochargers. Oil pressure entering a ball-bearing turbocharger needs to be between 40 psi and 45 psi at the maximum engine operating speed. For many common passenger vehicle engines, this generally translates into a restrictor with a minimum of 0.040" diameter orifice upstream of the oil inlet on the turbocharger center section. Again, it is imperative that the restrictor be sized according to the oil pressure characteristics of the engine to which the turbo is attached. Always verify that the appropriate oil pressure is reaching the turbo.

The use of an oil restrictor can (but not always) help ensure that you have the proper oil flow/pressure entering the turbocharger, as well as extract the maximum performance.


Too high of a oil pressure means oil travelling past the seals into your exhaust or intake. "Always verify that the appropriate oil pressure is reaching the turbo."

Min
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macBdog  



Joined: 16 Aug 2004
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Location: Brisbane, Australia

PostPosted: Sat Jan 12, 2008 6:11 pm    Post subject: Reply with quote

Just to re-update this thread after the server problems:

Steve (sbass) suggested that the crankcase could be overpressurised due to incorrect breather routing. This was the problem.

I rerouted my head breather and the smoke went away. Happy Days!
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p-talk wrote:
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macBdog  



Joined: 16 Aug 2004
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Location: Brisbane, Australia

PostPosted: Mon Mar 03, 2008 3:49 pm    Post subject: Reply with quote

Ok still not 100% on this.

Does anyone know how much oil the turbo should be getting? I have confirmed that my turbo drain is inadequate and have purchased a scavenge pump to take care of that.

Measuring the amount of oil coming out of the turbo:

bolt #1 yields 2litres a minute
bolt #2 yields 840ml a minute

at an increased idle of 1500rpm

So its obvious I can adjust the restrictor size to match the amount of flow required. But what is a ball park target for a ball bearing turbo? I can't find published or even anecdotal numbers anywhere?
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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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tuurbo  



Joined: 08 Aug 2007
Posts: 1446
Location: East Windsor, New Jersey

PostPosted: Mon Mar 03, 2008 4:20 pm    Post subject: Reply with quote

I don't know the answer but that's probably the best question I've seen on here in a year. I'd like to know the flow for our turbos too.

My first 'off the cuff' guess would be that you need more flow rather than less - so my guess would be the 2 litre bolt. This would be to avoid the possibility of oil gathering in the turbo, getting hot, blowing things and spraying into the air stream.
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Peter_in_AU  



Joined: 29 Jul 2001
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PostPosted: Mon Mar 03, 2008 6:07 pm    Post subject: Reply with quote

An article I read in Zoom magazine a while back would suggest that the lower figure (840ml) is more correct. Too much oil is as bad as not enough.

Probably more important than the volume or oil is the oil return. This must be totally unobstructed.
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