Boost leak? or worse?

[JLMazzella]

some background information...

i got a Vodoo MBC and a autometer boost gauge. Other then that the car is mostly stock. Problem is the car hits 9.5 ish psi boost at around 3k and stays that way all the way until i shift around 5k rpm. at half throttle u can hear the turbo's spooling, (sounds like swirling air). at around 75% throttle u hear a second swooshing noise, way more audible.... sounds like its coming from the left side of the car, and it sounds like the air is hitting the firewall. Ive checked all hoses numerous times and there all tight as crap. Anyone have any suggestions what could be leaking on the left side of the car? i thought at first my bov was leaking but ive definently narrowed it down to the left side of the motor.

[lawdogg]

Driver side or passenger side?

If passenger side, my guess is you have a stock BOV, and it's leaking.

[netmechanic]

Why even bother speculating?
http://www.3si.org/forum/f4/intake-p...-t6061-206269/

[yellowgto]

I'm all about rob beck's pressure tester and have one myself, but if you're in a hurry you could build one yourself on the cheap and be ready to test today:

RDR Intake Pressure Tester for a Turbo 3000GT or Stealth

[JLMazzella]

Ive ordered a robbeck tester. The swoosh is definently on the drivers side. i thought it was stock bov to but we ruled that out.

[netmechanic]

It will be easy to isolate with the RB unit plugged up, pump it up to about 12-15 pounds, be careful past that until you know whats going on, of your setup is stock things might start blowing off past that and a Y pipe can knock you on your butt if it comes off under pressure and your all up in it lookin for leaks.

[JLMazzella]

my problem just got alot worse. based upon all the signs i gathered the rear turbo was leaking from the outlet. i was checking the metal pipe that comes off the outlet, hugs the right side of the motor, and goes to the smic, and it was loose. I tried to tighten it, and it was getting snug, and i thought to myself " ok one more half turn) and snapped the dang bolt.

GOD i just turned a small headache into a much larger one.

I figured if something was leaking and not just popping off, and it sounded like air was hitting the firewall, that was the obvious culprit, now i gotta take the time to tap and rethread it or weld it... but i suck at welding aluminum. any thoughts?

[netmechanic]

Are you talking about the mounting bolt that holds the intercooler pipe to the plenum? If so then no biggie, just drill it out and put a helicoil in it, also I would think that if you had a leak so massive that air was rushing out and hitting the firewall to the point that you could somehow hear it then you would be building a big zero in the boost department. Just wait till you get the pressure tester and go about it the right way ,its gonna save you so many headaches from snapping bolts that arent the culprit in the first place and hours of stressing over possible causes of a boost leak that may not even exist. You could easily have a wastegate not closing, or some other issue, but rather than just taking random shots at it try and use a systematic approach, eliminating variables until the true culprit reveals itself.

[JLMazzella]

Nah its a single bolt that holds a aluminum pipe to the rear turbo outlet. on the tip of the pipe is a high tempered rubber gasket thats most likely worn out (it doesnt snug up at all to the outlet of the turbo). its pathetic how much play there is i dont know how it was getting a seal at all. Im gonna pull the bolt out and helicoil it today, anyone know where i can get that gasket at? ill get a camera later and snap some pics to clear all confusion (im bad at explaining things i know lol).

Thanx for all the help thus far.

Oh and i do agree that i should take a systematic approach to this. I just need my car for work so if i can quick fix something until parts arrive i will. And as for 0 boost, 9 psi on technically 1 and a half efficient turbo isnt that far fetch. if it takes 9 psi to break the seal that crappy gasket has that'd explain why im peaking at 9 and then i start to hear that wooshing sound from the rear turbo. That bolt was simply holding it in place with enough pressure to seal at >9 psi,

[VR3.9]

you can get that gasket at the dealer, not that much maybe 5 bucks. Still rediculously high for an .80 Oring. As far as the bolt goes don't sweat it too much mine snaped off as well. It was broke off flush. I just drilled through and re-tapped the whole. New bolt and good as new. If you don't care about the thread and bolt a 5/16 drill and 3/8's tap works just fine. I didn't have the metric stuff. Maybe 30 minutes work. Just don't break the tap off in it. Uh,,, than you got problems.