Turbo shot or something else?

pysical

Sergeant
Jun 16, 2017
450
105
0
Ride
2009 335xi E90
I have a Precision G2 DBB 6466 on my Speedtech kit. I just finished getting my car all back together and took it out for a drive. First couple of drives was just cruising not going into any boost. Then I started to go into boost slowly. I built up to 15 psi slowly and then the car just lost all boost (https://www.spoolstreet.com/threads/boost-target-drops-to-0-mid-pull.7931/). At first I was confused because the boost did not come out of the BOV. I also heard a weird noise when the boost dropped. So I thought it was due to the air filter falling off since it wasn't clamped down yet (just doing some testing). So at this point I wasn't sure if this was electrical or mechanical. I did another pull or two and logged them. Then I decided to clamp the filter down and it didn't do it again.

So I am guessing the turbo was sucking the inlet closed. Then I guess it stopped spinning the turbo? Anyways some stuff happened and I had to pull the manifold off. I figured I might as well get the turbo housing coated while it is out. I noticed some wetness on the outlet of the turbo so I took the housing off and thats when I noticed some oil pooled down into the housing and some leaking out from behind the wheel. I checked my oil catch can and its bone dry. I swabbed the hose that goes to the can and no oil residue. So I can only assume oil came from around the seals.

There is about 1/4th of a teaspoon (if that) in the bottom. I looks like more but it isn't. I am wondering if this is likely due to the collapsing inlet, and if this is a pressure thing where as long as it doesn't happen again, it wont leak. Or if it is a now the turbo needs rebuilt kinda issue.

I am going to call Precision tomorrow and see what they say and how much it would to basically replace the seals. The turbo has like 2-3k miles on it so I don't think the shaft, wheels, or cartridge will need repaired. I also don't want to tackle this myself.
 

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Dumaurier7

Sergeant
May 19, 2020
354
118
0
I have seen a turbo fail due to use of an undersized inlet air filter, what happens is because the filter cannot flow enough air the extreme vacuum created at the turbo inlet (because of the restriction created by the filter) the entyre rotating assembly tried to move forward causing extreme temperature resulting in premature wear at the thrust bearing! this eventually lead to localized overheating and fusion between the shaft and thrust bearing! You should hve the turbo taken apart and inspected.
 
Last edited:

pysical

Sergeant
Jun 16, 2017
450
105
0
Ride
2009 335xi E90
I have seen a turbo fail due to use of an undersized inlet air filter, what happens is because the filter cannot flow enough air the extreme vacuum created at the turbo inlet (because of the restriction created by the filter) the entyre rotating assembly tried to move forward causing extreme and premature wear at the thrust bearing! this eventually lead to localized overheating and fusion between the shaft and thrust bearing! You should hve the turbo taken apart and inspected.
I have been doing a lot of research on turbos in the past few days. Even talked to Precision and a few other turbo shops. I have always been worried about the turbo due to my bad experience with twins in the past. Anyways, I learned a lot and it seems that the turbo is most likely fine. It is leaking oil because that is how it is designed. When the turbo stopped spinning due to inlet collapse it went into a vacuum which basically sucked the oil out. I actually referred to this video (
) which explains a lot.

I think at most I will take the compressor wheel off and check the seal plate to make sure the rubber oring is good. Maybe replace the ring on the collar since it is right there as well. But won't be pulling the shaft out or anything.
 

Dumaurier7

Sergeant
May 19, 2020
354
118
0
If you intend to remove the nut and/or the compressor wheel you have to mark their orientations so that they can be replaced in the exact same position or you will need to re-balance the CHRA.