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Audible boost leak...but where?

holeshotmoe

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Moderately accelerating in 2nd or 3rd and I can hear air, ssshhhhhh, increasing louder and louder as boost climbs. The sound starts at about 7-8 psi and is preventing me from boosting above 15 psi or so. Checked the entire circuit except right at the turbo outlet, the bov, and the intake manifold. What's the most likely culprit? And are there procedures for testing the bov? Can I charge the manifold with the valves at TDC to hear leaks at the head seal? Have hard IC pipes, and a stock bov and manifold. Thanks.
 
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holeshotmoe

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Intake manifold is stock. IC and steel pipes are custom. Whatever it is, it began after I started cranking boost above 1 bar, almost as if it blew a gasket. Just wondering if it's more common at the manifold, the outlet at the turbo, or if the stock bov is known to leak. My bov is recirculated by the way, so I don't think it's that because it's really loud. Also, just before shifting when under load, the engine starts to break down (misfires), which I believe is because the AFR is screwed up from the leak (and another reason I don't think it's the bov).
 
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mitsuturbo

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you could have blown at a coupler, although i assume you triple checked both sides of each one
you could have blown a seam/weld on the intercooler. unfortunately i've seen this happen on a couple
 

cheekychimp

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Although I don't know if you can technically call it a 'boost leak' being pre-turbo, have you looked at the exhaust manifold? One other little problem I need to address on my car is a broken manifold stud/bolt. You can hear air escaping there.
 

mitsuturbo

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the one by the PS pump is always giving me problems, although i've never heard it "hiss" under power
 

cheekychimp

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^ Yeah, that's a good point, I doubt you would hear that from the cabin. You can probably disregard that idea /ubbthreads/images/graemlins/smile.gif
 

RedTwo

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Just to discount the obvious - have you recently removed the housing/can that covers the factory air filter and AFM?
 

vtecds1

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Las Begas
All I can say is take your time in finding the leak. It took me 2 weeks to sort out my problem. Here`s where I found my leaks...couplers, barbed hose fitting on turbo, ex-mani had 5 cracks on the welds, bov flange had a crack on the weld, t-body shaft seal was bad, AFPR vacuum line, wastegate hose and boost controller hoses.
 

get a toilet bowl coupleing from homedepot and a pvc end cap hose clamp them together drill a 1/8 inch hole for a air compressor fitting and tap it into the top. then set your air compressor at the desired boost you want ( using a hvlp pressure regulater helps) then put the coupler snuggly on the air inlet of the turbo snail and put your air hose on. do not go higher then the boost you will be running at. thats the way i also checked for leaks works great. you will hear the hissing noise and possibly feal air out of whereever you are leaking from. hope this helps
 

holeshotmoe

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Found this old post of mine and realized I hadn't followed up. It turned out to be a seam weld in the IC. Big fat tanks made of thin-walled aluminum resulted in them flexing as pressure increased. After a while they drew a crack. Rewelded and it blew in another place. Had someone weld it right and its working fine now.
 

James

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Apr 7, 2012
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Port richey Florida
I thought maybe you were just hearing your turbo spooling /ubbthreads/images/graemlins/rofl.gif
 

holeshotmoe

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Quoting EROCK970:
Get ur self a boost leak test. They are great thing to have


That's what I used to find the leak
 
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