After the clutch installment my car have never been the same. The car is laggy and does not want to go into boost. The car idles better and the 272/272 cams doe not lope as much now. Boost spikes.

I'm for certain there's a boost leak. I think I fix the BR lower intercooler pipe connection so the problem may be somewhere else. Just order some t bolt clamps so hope that will help with the intercooler and ic pipings.

I need to perform a boost leak test. Anyone know if the car needs to be at TDC or in some special configuration before a boost leak test?

Thks.

 

I guess I'm the only one having boost leak.

 

Pressure test your system, locate the leak and repair.

 

When I pressure tested mine I didn't rotate the engine to TDC. I have no idea what the crank position was at but it didn't leak through the valvetrain up to 30psi. I didn't mess with the throttle body to see if it would leak through the head. I think you'd be able to hear a differenec between leaking in the hardpiping and connections versus flowing through the head.

 

Thanks. We you able to use the in dash boost gauge or did you have a external boost gauge?

 

I just turned my compressor regulator down to an indicated 30psi. I didn't cross check it with my boost guage in my car.

 

just pressure tested mine last night.... i dind't even bother with tdc

 

I never bring my engine to TDC for my tests either. Major leaks are very audible.

Although it would be ideal to test w/ the engine at TDC since all the valves are closed.

 

You can't put the car's timing in any configuration where some valves won't be open. If you put #1/#4 at TDC, then some valves on #2/#3 will be open.

It doesn't really matter though if air escapes at that point since its after anything else that you care about testing. You do not even need to open the throttle blade. If you put 20+PSI through the compressor side of the turbo, it will be plenty to test all the way through to the intake manifold gasket and injector seals.

 

edit, just relized a noob searched for something and posted in it.

 

25 psi of pressure in the intake system is NOTHING compared to the pressures the cylinder sees when the engine is running. Combine an 8.8:1 static compression ratio with 20 psi of boost, the cylinder pressures should be in the hundreds of psi.

mike 99GSX, all the valves should be closed when the cams are in the TDC position, unless you have some weird cam configuration w/ cam gears, etc.

 

do as you wish, but i have seen 2 6 cyl. 1400 ft. lb. truck motors blow a head gasket, from testing with too much air.. here are some other probs with testing with too much air, blowing apart hoses, vacuum lines, plastic sensor housings, creating leaks in already sealed hoses that are clamped.. these things happen if your not careful, one pressure spike in your air lines can make for a bad day.. just trying too warn ya..

mike 99GSX, all the valves should be closed when the cams are in the TDC position, unless you have some weird cam configuration w/ cam gears, etc.

what... with one cam at tdc, all 8 valves would not be closed.. all 4 cyl. do not fire at one.. you can not get all 4 cyl at tdc at one time.. impossible.. and if both cams ran like that how would the motor run.. your theory only applies to 1 cyl at a time..

oh here is that link... http://www.vfaq.com/mods/ICtester.html

 

I disconnect 2 tubes, 1 @ the turbo compressor out discharge tube & the tube feeding the throttle body. Plug up discharge tube piece feeding the i/c & use a tapped plug to feed air into the system up top @ the hose before the TB.

This way, you are pressurizing the 95% of system & can listen for a leak & also see pressure loss / leakage. Any other way, you'll hear noises / leaks out of the turbo & or though your valve cover by the rings, through the exhaust=potentialy having you overlook a real leak.

I am not sure how everyone else does it.

 

If you say so

 

Thanks to everyone for the help. I've fixed the leaks, the ones that I was able to hear and see anyway. I think my DP and lower intercooler pipe may slightly be leaking but not sure if there's a way to tell for sure.

You guys do realize this post started in Sept. 16 2004