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MBC bleed hole question

Old Jul 25, 2007 | 04:39 PM
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MBC bleed hole question

Since I couldnt find the answer direct answer when I searched, I was wondering when is the bleed hole at what psi level suppose to start hissing when u r doing a boost leak check? Mine started at .5 bar is this normal?
Thanks in advance
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Old Jul 25, 2007 | 05:47 PM
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bump for an answer come on guys
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Old Jul 25, 2007 | 06:43 PM
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When I had the Forge it started at about 12psi.

Not sure when my AMS MBC bleeds now.
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Old Aug 27, 2007 | 08:44 AM
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Bump to this thread

I have a Forge MBC, the bleed hole is always open. I've done a boost leak test, the pressure on the system will fall down from 15psi to 0 after 1 min. Is it normal?

Otherwise, the car holds boost to 23psi @ 3500rpm with no problem to 20psi at redline.
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Old Aug 27, 2007 | 08:59 AM
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the bleed hole is always open. air is vented out of it when the ball and spring open up. when the ball opens up depends on how stiff the spring is set to, and isn't going to be the same for everyone. because the boost controller is a "restriction", in other words a pressure drop, before the wastegate, when it opens up depends on where you have that "restriction" set to.

the best way to boost leak test it is to take the two vacuum lines on the MBC, and connect them together and take the MBC out of the loop so that it doesn't leak.
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Old Aug 28, 2007 | 12:36 PM
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So it's really normal to have this "hole" open during the boost leak test
Thanks for the answer.
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Old Aug 28, 2007 | 01:20 PM
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or if you don't want to disconnect your MBC just crank it down 3-4 turns and it should bleed off. You only need to pressurize your system to 15psi (1bar). Just remember how many times your turned the MBC so you can turn it back when your done.
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