Boost Leak Checking Guidance

[rkern]

I’ve been trying to track a boost leak down for over a year it seems. Car drives fine, seems to boost fine but I’m being told I have a boost leak by tuner. I’ve pressure checked, I’ve smoked it and I don’t seem to find anything. This is a stage 3 car with BW ko4s. Just trying to figure out what gets pressurized when doing a check so that maybe I can work backwards in checking it.

I get the basics. Into the y pipe, down through the inlets, into the turbo, through the intercoolers, into the bipipe. I know there are the vacuum lines that sit across the IM.

Any help to self isolate is appreciated. Image1671140982.902025.jpg

This a log of what I’m talking about.


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[TwoSnelz]

Take every line off the intake manifold and run pressure into them with a mityvac to test the check valves.

Run pressure into the line that connects to the short side tee on your N75 to test for leaks to wastegate.

Pressurize the diverter valves on both sides(pressure side and control nipple) and jury-rig a leakdown tester to determine if they are leaking.

Added this video to clarify...
https://youtu.be/I0RtUa2oR20


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[rkern]

I’ll give that a go. Thanks.


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[TwoSnelz]

No problem good luck, may want to check injector orings too.

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[Silverex]

What I try to do is remove Y pipe/claws and hook boost leak tester to upper inlet pipe. Then cap off your bi pipe or intercooler so it can hold pressure 100%…way easier to find leaks that way.

You’ll only be testing the pressure pipes but most of time that’s where the issue lays.

With that said, that’s a very odd boost curve and I’d be taking a real good look at the wastegates/flappers also.

[TwoSnelz]

To piggyback on silverexs point, you can test each side separate this way as well. But since your smoke test didnt reveal anything I feel your leak is internal and those arent fun leaks to find.

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[rkern]

To piggyback on silverexs point, you can test each side separate this way as well. But since your smoke test didnt reveal anything I feel your leak is internal and those arent fun leaks to find.

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I have been told it could be internal. What would be an example of an internal leak?

[CELison]

I have been told it could be internal. What would be an example of an internal leak?

Failed check valve.

[rkern]

Failed check valve.

I’ve replaced both green ones. I don’t know if it’s a check valve or just a tee, for the boost gauge has been replaced. The only one I haven’t replaced and not sure if it would cause a boost leak would be the one on the spider hose.


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