adrian-1

I had a problem with my Greddy turbo kit holding boost. My boost gauge showed it got up to 6psi for 1 sec, then it dropped to 3 psi for the rest of the rpm's. I double checked all the vacuum pipe adaptors and hose clamps but all seemed tight.
After surfing the web I found that it was fairly simple to leak test a turbo kit. You just have to remove the intake portion and cap it off , then fill up the turbo inlet with the max psi your system is designed for (greddy is 6-7psi).

I found a 3" cap/w gauge to plug the intake inlet here for $20. You can make your own, but I figured it would probably cost me the same amount for all the parts.

What you'll need:
- a plug like the one mentioned above (gauge isn't necessary, but safer)
- air compressor (to fill up the turbo system with air- do not go over max psi)
- check valve (one way valve for the "jet air fuel mixing" hose - has a yellow mark) autozone sells it
- 2 rubber plugs to cap off the inlets on the intake pipe (autozone sells the plugs)
- spray bottle with water
- screwdrivers/ socket set to remove intake parts.
- a second person to help (1 person pumps the air in, the other listens and finds the leak)


Steps:
Remove the airnix intake and the MAF attachment. Remove the black rubber piece from the airnix intake. Insert the plug w/ gauge and use a hose clamp to get it onto the intake pipe.
Remove the 2 hoses on the intake pipe and cover the nipples using the rubber caps.
Insert a check valve onto the hose with the yellow line (jet air fuel mixing hose). If you don't air will escape out through here when your pumping air in. I actually left the check valve in permanently so no air escapes through here during boost. Some other forum member has done this and noticed an improvement. Benny at Greddy also recommeded to do this.
I jacked up the front of the car and also removed the front passenger wheel to be able to reach the hose clamps.
Your ready to pump air in.
Have a friend fill up the inlet and tell them to stop when it reaches 5-6psi.
Listen for leaks, they'll be fairly loud and the gauge will drop to 0 quickly. Spray water onto the pipe connections if your not sure what side it's leaking thru, bubbles will appear where the leak is at.
If it's tight, you shouldn't hear any air escaping.

Video (1.3MB) of how fast the gauge dropped with the leak. After fixing the leak, the gauge still dropped to 0 but it took 3 times as long to get to 0 and there were no leaking sounds.
[anybody who tries this leak test... could you also try to plug the exhaust outlets with a plastic bag and tape and see if the gauge takes longer to drop than without having the exhausts plugged. ] I forgot to try this.



I quickly discovered my leak was at the boost gauge hose connected onto the intake manifold nipple. It had a small tear and I didn't notice it when I checked all the hoses/ clamps earlier in the week. I remember taking it off/on a few times to test whether it mattered which nipple it was on.

adrian-1

air compressor and hose with slit in it.

zoomzoom_8

so you don't have to use a hose clamp on the plug itself just the hoseclamp to secure the airnix fitting to the intake pipe? Thanks, just got my tester toady and will be testing away tonight.

Chris

zoomzoom_8

so you don't have to use a hose clamp on the plug itself just the hoseclamp to secure the airnix fitting to the intake pipe? Thanks, just got my tester toady and will be testing away tonight.

Chris

adrian-1

I had to use 2 hoseclamps. 1 for the intake pipe and another for the plug.