Garrett GT15 oil control - Tel?
Turbo Mini Forums

For awhile I thought I had scavenging pump problems on the drain, but now have concluded that too much oil pressure is getting to the turbo. Once the oil is hot, higher RPM running gives a cloud of smoke when you stop and idle. Also, there is oil in the intake pipe as well.

So - oil is blowing past the turbo seals. Engine runs 70-75psi at cruising RPM. I have a 0.065" restrictor in the line, but that does not seem to be doing the job.

Tel, what size restrictor are you running? Anyone else have Garretts and can share restrictor size?

1275 with Back Door Turbo

am running a T28 (79 Trim, .86 A/R Housing) and had similar issues to yourself, going down to a 2mm(0.078 inch) restrictor, got rid of most of my prblems, only now get some smoke if i accelerate after idling for 20 mins or more. is the GT15 a ball bearing unit? im sure these can take a much smalle rrestrictor, but best google and see what you dig up.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

With my GT15 I'm not running a restrictor, best info I got was that it didn't need one but remember some other models did.. maybe the ball bearing type??

-----Edit----
hmmm.. I may need to look into that agin but it seems to be mostly for the ball bearing types..

http://www.atpturbo.com/Merchant2/merchant...y_Code=ATP-OIL1

and

http://www.atpturbo.com/Merchant2/merchant...y_Code=ATP-OIL1

Edited by Turbo Tel on 2nd Nov, 2007.

website:- http://www.terryhunt.co.uk

Ahahhh!!!

try this one..


http://www.atpturbo.com/Merchant2/merchant...y_Code=ATP-OIL1

website:- http://www.terryhunt.co.uk

Thanks.
I've just gotten a pressure gauge and some fittings. Will get that together this weekend and see if there is excessive pressure downstream of the restrictor. If not, the seals may have gone out of the turbo. It always smoked some - not sure if it is really worse now or not.
I've also bought an adjustable brass needle valve - if there is too much pressure, I'll be able to change it.
GT15 is journal bearing, not ball bearing. Corky Bell says in his book that no turbo needs more than 25PSI at full tilt, and only 5PSI at idle.
I received an e-mail from a Garrett dealer who said that if mine is smoking with the 0.065" restrictor it is a drain plumbing problem rather than excess oil flow. Will find out for myself once the gauge is hooked up.

Edited by fortfun on 3rd Nov, 2007.

1275 with Back Door Turbo

A friend had similar problems with a Turbo. It turned out to be a restrictive drain rather than excessive oil pressure/flow.

WWW.TURBO-MINI.COM

Hi,
The Fiesta RS Turbo (T2) suffers terribly with oil drain problems.
Also if the oil itself is too thin you'll get the same problems, on a T3 at least....
Cheers,
Gavin :)

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Ensure the drain is totally clear and free flowing.
Although going down in steps of 5thou might not be a bad idea. Just dont go smaller than about 40thou.

NOS Nitrous jets are handy to use for restrictors.
But dont restrict to get the pressure down, at the expense of oil flow...if thats possible.
Normally restrictors go right at the turbo itself.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

yup, i too ha a smokey turbo due to a poor drain.

Drain appears perfect. Hoses all clearly visible and no kinks. What else should I check for? Suppose I could put a pressure gauge on the oil outlet from the turbo to make sure there is no pressure, but it seems unlikely to have any pressure viewable on a gauge.

I put a pressure gauge on after the restrictor, and a needle valve before the gauge so I could adjust pressure. Once the oil is good and hot it is smoking even with only 20psi going back to the turbo at idle.

I've concluded the seals are shot from running too long without a restrictor. Enquiring with the distributor for an exchange price on a rebuilt unit.

1275 with Back Door Turbo

Hi,
Dropping the engine oil pressure a little would help here. Vizard recommends a maximum of 60psi.
That would make it easier to control the pressure to the turbo and not heat the oil as quickly.
Cheers,
Gavin :)

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Hmm... Response from a turbo vendor:

The exposure of the turbo to high pressure will not damage the seals unless
you have bearing damage due to something else which could take out the seals
due to shaft wobble. Somehow you're building oil at the end of the housing
and the next time you start up the engine, it smokes and burns it off.


The vendor who sold me the kit also said that the turbo seals are unlikley to be bad. They are sending me a check valve to ensure that oil does not drain into the turbo when the car is shut off.

So maybe this won't cost a bunch of money after all.

I'm thinking check valves at turbo inlet and outlet perhaps.

1275 with Back Door Turbo

Could be a factor, bearing in mind where your turbo is sited. Are check valves common in that type of installation?

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Apparently yes. STS now includes them with kits - apparently the change was made around the time of my purchase, but I don't seem to have one.
Also found some discussion of this same problem between some Camaro guys - theirs was solved with check valve on the oil inlet.
I also found out that aircraft with low-mounted turbos use check valves to prevent oil draining into the turbo while shut off.

Edited by fortfun on 6th Nov, 2007.

1275 with Back Door Turbo

Sourced a check valve and fittings today. Might be a few days before I get it put on. Hoping for a cure!

1275 with Back Door Turbo

Check valve in. Drove it about 35 miles on the highway hoping to blow the oil out of intake and exhaust piping. Unfortunately the boost pipe blew off the carb hat 3/4 of the way through the trip. Stopped and reattached, tightening with a vengeance this time. Had to drive about a half mile to a mile before getting to a good spot. It was smoking again when I idled in the parking lot. I've read that having the compressor spinning but not generating boost will cause the bearings to blow out oil, so this may not be a fair test given the pipe blow. Will have to drive it awhile and see if the smoke clears.

1275 with Back Door Turbo

Given where your turbo is located, is your scavenge pump working properly ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Seems to be. Not getting smoking while rolling down the road, where oil pressure is higher than at idle. It smokes at idle. I've got an uprated alternator, and a voltmeter built into the Prologger. I turned the idle up to 950 RPM awhile back so that the alternator puts out no less than 14V because I was wondering if the scavenging pump was slowing down at idle. No change.

Edited by fortfun on 9th Nov, 2007.

1275 with Back Door Turbo

Hi,
Have you always had this problem or has it developed recently? How old is the turbo, what sort of miles has it done?
I had the same problem with the T3 on my Cosworth 10 years ago, a change of oil sorted it, still going strong.
What oil are you using?
Cheers,
Gavin :)

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Always had the smoking.
Turbo was new when installed in May 2006.
Smoking seems a bit worse lately - running Castrol 5W50 oil.

1275 with Back Door Turbo

Hi,
Oil could well be too thin I use 15w50 in the Cosworth and that's a more modern engine...
Cheers,
Gavin :)

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