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Old 11-02-2011, 03:06 PM
Steve530 Steve530 is offline
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Location: Knoxville, TN
Join Date: Dec 2007
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Mein Auto: 2001 530i
Originally Posted by bluebee View Post
In the annotation below, do I at least have the direction of molecular flow correct?
Yes, that is the flow.

Brake boosters (or servos) have long been connected directly to the intake manifold as a source of vacuum. The suction jet pump is supposed to supply additional vacuum to the servo.

My understanding of the suction jet pump is that the lower hose connects to the intake manifold. This is a good source of vacuum which evacuates the servo through the top tube. The vacuum from the manifold also pulls air from the intake boot between the air filter and throttle body through the smaller fitting that is angled from the main body. The air in this stream goes through a venturi that creates a lower pressure area that actually pulls more air from the servo than the manifold vacuum alone.

I found a picture of a suction jet pump that was partially cut on a VW Passat forum. It appears to be similar to the ones used on the e39.
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2001 530i/5 S+P CDV delete/Akebono ceramic pads
M5 SSK/RedLine MTL/M5 rear sway bar/Bilstein HD

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