I am in the middle of a pressure test and im getting air leaking from the small hole in the Hallman MBC. If i remember correctly, the nut with the hole is not supposed to be tampered with.
So would it be safe to say my MBC is no good?

 

It is supposed to leak. That is how a MBC functions. It bleeds boost off once the turbo reaches the desired pressure. When you do a boost leak test, you need to unplug the pressure source line going to the MBC and cap it off the hose (stick a bolt in it).

 

thanks mike,
just got the same answer after calling dynoflash.

 

same thing happened to my buschur mbc tonight..... was doing the pressure test..... and air was leaking from it.... glad to hear that it's normal