Pressure testing for leaks, for how long should system hold pressure?

[Jonas_R]

Well,

If i do pressure testing on my system on say the small vacuum hoses (ID 4mm) if i give the system 2 bar pressure. How long should the system hold this pressure?
Or say it drops 0.1 bar in 30 seconds or perhaps 1 minut, what be oki and what would not?

Iam guessing the answer is the same if your testing the big hoses from the turbo to the inlet.

/Jonas R.

[dkw_dude]

I'm not sure about this myself, but I pressure tested the intake yesterday from intercooler inlet (to exclude leakage in turbo seals) and the pressure fell from 15 psi to 5 psi in 1 minute. And to 0 psi in another minute.

Tested the small vacuum hoses separately, no pressure loss. Also had soap water on hoses to look for bubbles, but nothing. All big pressure hoses are now black Samco

And when the pressure was going down, I heard a hissing sound which became stronger when I removed the oil cap. So I think this is piston ring blowby (had bunged the PCV when I did this). Can't see any other way that the escaped air can go into the crankcase.

Is this amount of blowby acceptable?

Tested the cylinders for leaks a few days before, all were ~9-10Bar, should be ok.

Cheers, Leif-Helge