Boost Leak Test Problems

[Dootwah527]

Okay, I made the boost leak tester like the one on vfaq. Whenever I go to pressurize it, I hear all of the pressure going right out of the exhaust (I can actually hear it comming out of the exhaust pipe). I tried setting cyl 1 at TDC(I think), and it still does the same thing. If I take the plugs out, air blows out of the top hole. If the plugs are in, air blows out of the exhaust. I can only reach about 3 psi with a big air compressor. Any Ideas?

 

[herostar]

That shouldn't be happening, maybe your timing is off. One way to get around it would be to cap off your UIP right before the throttle body elbow.

 

[Dootwah527]

I tried that, and now my cbv is releasing the air after a certain psi (of which i cant tell exactly when it is capped off). Its a Greddy type s

 

[steve]

You must make sure that your engine doesn't have any piston at the top if it's stroke when pressure testing. If it is then either it or it's partner will have the valves in overlap and both the intake and exhaust will be open. about 30 degrees before or after TDC is a good spot where no more than one valve set in any cylinder will be open.

If your still getting leakage to the exhaust and you have good compressions numbers you should look at the EGR valve and make sure it's not leaking. If your compressions numbers are bad you may have valve problems.

You need to make sure that the BOV nipple is getting the same pressure as the intake during testing. If the upper chamber isn't, then the air pressure will force the BOV open. During normal operation the pressure in upper chamber and the lower will be equal and the spring will hold the BOV closed.

Steve

 

[Dootwah527]

Well, thanks for the help. It worked and I have been busy searching for these stuipid boost leaks. Thanks

Jordan