Vacuum/pressure test
 

I used a PVC cap and plugged 1 side of the intercooler, used an air compressor to pressurize a nipple off the UIM. My buddy and I found quite a few bubbles in the soapy water in many different places.

So we fixed those and retested. Now we can't find any bubbles anywhere.... But it doesn't hold any pressure for any length of time? If we put about 8 psi on it, it leaks completely to zero within maybe 5-7 seconds.

We rotated the front main pulley to move the rotors to different positions and never found a spot that held any longer.


Would that be normal? Maybe leaking around the actual internal seals? What do you think?

Try repeating the test without the intercooler in the plumbing to be tested. If there's a leak in the intercooler, it would seem difficult to pinpoint and correct. Test one part alone. If it passes, add another one and re-test, then keep repeating untill the whole intake is reassembled

Well, I should have said that.


We tested with and without the intercooler and piping included. So the intercooler didn't change the results

Does an engine hold pressure indefinitely?

Apex and Side Seals have to hold compression which is 80+psi, so it would hold normal boost pressure. Checked all of the devices attached to the UIM & LIM such as the ACV, BAC, injectors (and their seals) and so on?

No, I had the same results when I pressure tested mine. Except I did the entire system, my pressure source was the turbo inlet. The engine allows a good amount of air to go through, same thing with piston motors from my experience.

the engine itself won't hold pressure, all the seal clearances are also places where it will leak air, not to mention anything that is worn.

even a piston engine won't hold pressure very long. with a piston engine they do a thing called a leak down test, and you basically screw the shop air compressor into the spark plug hole and it has a thing to measure leakage, if it holds more than about 80% its good.

This is good news, and what I wanted to hear