Boost leak with fluid sound

[Der Konig]

EDIT: Just to update, it turned out that my Forge DV failed. Not exactly sure how, but I am taking it apart to investigate. Had a spare revision C dv laying around. put that in and was good to go.

So i just did a boost leak test with the pvc pipe with fitting and compressor trick. My car is underboosting obviously.

The sound I heard is very strange, it sounds like air is bubbling around in the oil, down in the pan maybe? Only connection to the oil system I can think of is the pcv system, I have a 034 catch can. Is the return line from that allowing air in? Wtf?



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[Der Konig]

Figured I needed to drain my catch can anyways, so I took the return line off and pressurized it. Not happening there. Any ideas?

Bueler?

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[Denio24]

Boost leak testing with a compressor will push air past the piston rings causing or through the turbo thus the bubbling sound i believe and it is normal. This test method is most helpful (and fastest) when there is a large but hard to find leak. And I hope you are testing with the oil cap removed as it will allow you to run the test for longer without pressurizing the crankcase. If there is no noticeable hissing sound then you probably don't have a boost leak.

Why do you think your car is underboosting?

[Der Konig]

Interesting, good to know. Answers that question.

My car will jump to full boost and then taper off, sometimes struggling to even get to full boost. No shaft play, I just replaced the turbo.

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[rongeur]

Codes?
Peak boost?
Tapers to?
Boost request vs actual?

If you are boost testimg through the turbo inlet you will have a slow leak through the turbo bearings and the rear PCV area if it doesn have the late revision check valve. Better to boost leak test after turbo as that is where the positive presssure is applied by the turbo, not before it.

[Der Konig]

Makes sense, no codes. Peak boost can be 20 psi but tapers. Tapers to 8 to 10 psi. I'll do logs asap. Been a busy week.

Thanks for input.

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[Der Konig]

Double post

[Der Konig]

Will try to log tonight, but on my way to work I noted the behavior better. I have had one 20ish 22 ish spike when I originally got into boost after the new turbo. Now it will only boost to about 10 psi and sit right at it.

My thought is the initial full boost scenario knocked a connection loose and now only allows the 10psi condition due to a leak. I can't hear anything when I charge the system though, besides that bubbling which turns out is nothing.

Has anyone had any issue with the Forge DV? Feel like it would be a weird time for it to fail, but having a hard time finding anything else. May take it in to get smoke tested.

One thing I did notice, it looks like the breather hose for the pcv system on the turbo side (metal L shaped breather connected by two m5 hex bolts onto the turbo) has a piece that got pinched or something on the end on the rubber part. So there is a small chunk missing from the end of it in a V shape, but there seems to be plenty to clamp down and create a seal. Not sure if that could be a cause or not. Having trouble finding just the rubber part though, may have to order the whole thing to check.