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Is my turbo bad Last opinions before I replace it

Old 04-20-15, 07:22 AM
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Unhappy Is my turbo bad Last opinions before I replace it

So, here is the scoop:
Freshly built S5 13BT streetport
Used Garrett GT4088R
  • No abnormal shaft play
  • No oil residue in either housings prior to startup
  • 0.035 restrictor on -4AN inlet
  • -10AN oil drain with straight fittings and <90*bend, doesnt droop below drain port. (posted below)

The new engine started no problem, but after a few minutes of idling began to smoke VERY badly.
After idling for approx 1/2 hour and checking for leaks, the smoke hadnt subsided which reinforces my theory that the turbo is bad.
After letting the engine cool down, I pulled the downpipe off and found it was coated in engine oil, it literally poured out the pipe.
I pulled the EGT probes (pre-turbo) and they were dry.
This gave me the feeling that the engine seals were not the problem.
As a last resort, I decided to isolate the turbo from the engine. I put a hydraulic needle valve in the oil feed and stalled the compressor wheel to prevent the shaft from spinning dry.
Idling the engine with the turbo receiving no oil, the smoke went away after a few minutes.

Is there anything Im overlooking before I shell out the cash for a new CHRA from Garrett?
The BB CHRA exchange program they have allows me to get a new CHRA for approx $800. Is that really worth it? I didnt pay much for this turbo, but there are a lot of other options for <$800 (BW S300), but Im not sure if the ball bearings are worth the premium.
Also, I already have a downpipe and manifold that will clear the GT40R. If I changed turbos, Id probably have to change the downpipe at a minimum.
Thanks in advance.

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Old 04-20-15, 08:35 AM
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I forgot to mention,
I ran the engine with the oil filler cap OFF, so no crank case pressure.
I tee'd off the feed line for an oil pressure gauge and was seeing approx 100psi cold and 45-50 psi idle. Running 10w40 conventional oil.
Oil pressure at the turbo should be much much less since it's going through the 0.035" restrictor.
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Old 04-21-15, 08:42 AM
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Tonight I'm going to remove the CHRA and bench test for pressure leaks.
My plan is to fill an aluminum vessel half way with oil. A port on the bottom will connect to the feed line for the turbo. The top port will be connected to regulated compressed air (50psi to start, 100psi if it passes first round). Once I pressurize the top half of the tank, oil will be supplied to the CHRA. With the housings removed, I should be able to visibly see oil leaking. And with the drain open directly to a bucket, this will remove any chance that my drain was the issue. I should have some results tonight.
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Old 04-22-15, 07:57 AM
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Well,
My test worked and it didn’t.
I was able to bench test the CHRA with whatever oil pressure I wanted. I used 100psi and 5w30 to emulate a higher rpm warmish oil temp.
No leaks were seen from the turbine side, but the heat shield makes it hard to see much.
If I kinked the line severely, I could hear oil passing by the seals and eventually running out the heat shield. I think there is something to be said for having the wheel spinning while under pressure, though.

For good measure, I swapped to a ” oil drain hose.
Hoping that that’d fix my problem, I re-installed the CHRA and started up the car.
This time, I left the oil feed “turned off” with the a needle valve and the turbine wheel stalled with a socket on the compressor.

The car started up with no smoke and no drama.
After the car was warmed up a bit, I turned the oil on and freed the compressor.
Queue the smoke show. Big white clouds of smoke.
I’m going to contact the local Garrett rep today and inquire about the BB CHRA exchange program. Last I was quoted was almost $800…
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Old 04-26-15, 08:39 AM
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SO, to close this thread, I bought a new CHRA and it completely solved my smoking problem.
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Old 04-29-15, 09:41 PM
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Glad you got it sorted out. Appeciate you posting all your findings and closing the loop.

This section used to get a lot more traffic, surprised to see zero responses here.
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Old 04-30-15, 06:43 AM
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Thanks,
I'm a bit surprised I got zero feedback too.
Either way, any advice to check other avenues wouldn't have helped.
I swapped out the CHRA using Garrett's BB exchange program. A new GT4088R is about $1800, a CHRA is $1024, I paid $624 + state sales tax and shipping to/from for my core. Not all that bad for essentially a brand new turbo that I paid peanuts for to begin with.
After changing the CHRA and nothing else, the car does't smoke at all. It needs tuned badly and is now having clutch issues, but all else aside, the turbo is sorted.
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