This is fu*k up

[Matt D.]

Every time I've seen and done a boost leak test the adapter you apply air pressure to is connected to the inlet of the turbo. This ensures that the entire intake system is pressurized and tested all the way from the turbo to the intercooler past the blow off valve into the throttle body, intake manifold and head. The engine itself will hold enough air for it to keep a steady pressure while you listen for leaks.

[tpunx99GSX]

I would say air is leaking past the rings (as most have said this is normal for dsms) What plugging up the TB hose does is checks just the pipes from the turbo through the IC up to the TB. But nothing should be going into the head, unless like someone said earlier, the air is going from the BOV line to the Valve Cover.

[1ViciousGSX]

Moved to tech forum:

Without the throttle body hooked up, the only way for air to bleed off into the crankcase would be through the turbo seals into the oil pan. There is no other connection to the crankcase other than the turbo drain with the way it was done in the first post. The BOV takes its boost/vacuum sources from the intake manifold and turbo after the compressor. Even if the BOV is blown or leaking, it wouldn't get into the crankcase, it would leak into the intake manifold and go out the throttle body or straight to atmosphere.

[4g63tcrazy]

Oooor if his pcv valve isn't working properly it could be going straight into the valve cover from there. You have a good point about the turbo. Forgot all about that..

[1ViciousGSX]

PCV is not an issue because it's not seeing any pressure from his testing method. The intake manifold was not pressurized.

[CarPsyco84]

I did not realize he was not pressurizing the intake manifold at first... I think viciousgsx is right, that would be the only way for the air to get into the crankcase... Like the slight leakage past the rings in the engine, a little air leak is probably ok, if you can't even build pressure its probably not.

1 flaw to boost leak testing without pressurizing the intake manifold is most BOV's are driven off the intake manifold and actually use the boost pressure to help them stay closed, so they will start leaking at a lower pressure than if the whole system was under pressure.

[scheides]

Moved to tech forum:

Without the throttle body hooked up, the only way for air to bleed off into the crankcase would be through the turbo seals into the oil pan. There is no other connection to the crankcase other than the turbo drain with the way it was done in the first post. The BOV takes its boost/vacuum sources from the intake manifold and turbo after the compressor. Even if the BOV is blown or leaking, it wouldn't get into the crankcase, it would leak into the intake manifold and go out the throttle body or straight to atmosphere.

Good discussion.

First off, the way you're doing it by disconnecting the UCIP from the throttle body is not how I normally do it, but it is good at isolating an issue with a leaky BOV and/or turbo seals.
As, is, answer these questions:
1) Is there any air coming out of the BOV?
2) Does the system hold any pressure at all? Or does it all just completely blow out of the valve cover breather? You should at least be able to build it up to 10-15psi, unhook pressure, and have it sit there while you look for leaks.
2a) if you block off the valve cover breather w/ your finger, does it leak anywhere else? Just a small amount of boost would be a fine test, 3-5psi.

Next, hook up your UICP to your TB again and do the test. Again, does it hold *any* boost or does it all just leak out instantly?

Side question: did you have shane do a leakdown test? That should really let you know if there's a problem with your head.

[Ronnie S]

Moved to tech forum:

Without the throttle body hooked up, the only way for air to bleed off into the crankcase would be through the turbo seals into the oil pan. There is no other connection to the crankcase other than the turbo drain with the way it was done in the first post. The BOV takes its boost/vacuum sources from the intake manifold and turbo after the compressor. Even if the BOV is blown or leaking, it wouldn't get into the crankcase, it would leak into the intake manifold and go out the throttle body or straight to atmosphere.


I didn't think about it until it was said, but this is a very good point. Maybe even go as far as blocking off the turbo outlet and do another test to verify it even more.

You mentioned that your timing tensioner went bad, was it the hydrolic part or the pulley. Does your timing belt get lose after sitting awhile? This Would mean the tensioner pulley isn't adjusted properly.

[scheides]

I didn't think about it until it was said, but this is a very good point. Maybe even go as far as blocking off the turbo outlet and do another test to verify it even more.


Great idea!