Testing for boost leaks

[Honest_Bob]

I've made a boost leak tester so I could look for possible boost leaks after I put the fmic on. I replaced the ghetto throttle body coupler I had with the proper silicone reducer and it fixed that leak. The car will now hold pressure for a couple minutes 2-3 while very slowly loosing pressure. I still hear a hissing sound in or around the throttle body area. I cant seem to locate it. I dont know if its supposed to do that or not.

How long SHOULD I be able to hold pressure? I'm not sure if I'm doing it correctly. I did read that something was supposed to squeal around 15psi, and it does.

[AztecTT]

Don't know much of anything about Subies, but is there a paper gasket for the TB?

Spray some soapy water over the area and his the throttle, under boost you might be able to see where it's occurring.

[TROLL]

My boost drops quickly when I'm testing for leaks, but its because its unlikely that all the valves are closed at the same time.
When I test for leaks I use the tester I made and bring it up to about 25 psi and just listen... you'll hear any leaks at that point. If you're not sure exactly where its coming from then the soapy water has always worked well for me.
The pressure normally drops fairly quickly (~20 seconds) to 10 or 15 lbs then slowly contiues dropping after that for me, so I just repressurize as needed.
Oh, and I forgot the real reason I was responding... are you pulling the breather lines off of the turbo inlet and capping those off? Just want to be sure because they need to be disconnected, they're not meant to see positive pressure...

[Honest_Bob]

Originally Posted by TROLL

are you pulling the breather lines off of the turbo inlet and capping those off? Just want to be sure because they need to be disconnected, they're not meant to see positive pressure...

Nope! Thanks!

Soapy water isnt helping me at all.

[TROLL]

ok yeah you can blow out your front or rear main seal that way, you're pressurizing your crankcase and its not meant to see pressure. you're probably fine but just dont do it any more. you need to pull those hoses off and you can just leave them open. you'll obviously need to cap off the open ports on the turbo inlet though in order to pressurize the system.

[04wrbsti]

Originally Posted by Honest_Bob

I did read that something was supposed to squeal around 15psi, and it does.

Squealing is from the el-cheapo regulator going to the fuel purge canister. Once you get around 15psi or higher it starts squealing, and eventually it will probably break.

[redline]

You are holding for 2-3 minutes...thats a godsend! That will not effect your boost at all and I think that is perfect.

Try replacing your TB seals if you feel the need, the Evo has problems in this area also.