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-   -   Anyone Had Power Brake Booster With a Vacuum Leak? (http://www.bimmerfest.com/forums/showthread.php?t=649503)

dc_wright 10-02-2012 04:18 PM

Anyone Had Power Brake Booster With a Vacuum Leak?
 
I think I may have a vacuum leak in my brake booster. I have a turbo like whistle I can hear better from inside the car than from the engine compartment, I have power boost to the brakes but the effort feels higher than it should (definitely higher than my E46 by comparison), and when I hook my vacuum gauge directly to the manifold I get 19", but when I tee in with the brake booster connected in I get 17"-18". Also when I apply the brakes with the vacuum gauge teed in I get a vacuum drop (expected) but it takes several seconds to build back up to 17".
Anybody had this before?
I've sprayed brake cleaner all around the intake manifold and the associated hose connections without any vacuum leak associated signs, but the "turbo whistle" persists.

Echo46 10-02-2012 05:02 PM

Have you inspected the intake manifold adjuster-DISA Valve- for leak and/or functionality?

drivinfaster 10-02-2012 05:42 PM

disconnect the vac feed to the booster, block it off, and see if vac increases. if it does, then suspect a leak.


if you have a vac pump, you could also use an adapter to fit the inlet, and then apply vacuum. if it holds, then no leak. if it does not hold, suspect a leak.



df

dc_wright 10-02-2012 05:44 PM

I would if I had one. :) It's a 328, not a 318.

drivinfaster 10-02-2012 05:46 PM

Quote:

Originally Posted by dc_wright (Post 7109751)
I would if I had one. :) It's a 328, not a 318.

:confused:


df

ZeGerman 10-02-2012 05:51 PM

^I thought only 318s had DISA valves, too.

dc_wright 10-02-2012 06:00 PM

Quote:

Originally Posted by drivinfaster (Post 7109746)
disconnect the vac feed to the booster, block it off, and see if vac increases. if it does, then suspect a leak.


if you have a vac pump, you could also use an adapter to fit the inlet, and then apply vacuum. if it holds, then no leak. if it does not hold, suspect a leak.



df

I probably wasn't clear in my OP. When I disconnect the vac feed to the booster I get 19". When I tee into the vac feed line so that it's connected to the manifold and the booster is when I get 17"-18".
I've got a mighty Vac and when I connect it to the booster hose I don't think I've been able to get the one way valve to open so I think I've only been testing the hose......I may just have to pump the crap out of it for a while to verify I've got it really evacuated.

drivinfaster 10-02-2012 06:12 PM

a smoke machine would also work, but not many of us have those...

if it leaks, it's visible.



df

dc_wright 10-02-2012 06:31 PM

I think it may be the grommet where the one way valve plugs into the vac booster. When I tried pumping it down when the hose was connected to it I couldn't get it to hold anything. I popped the one way valve out along with the hose and pumped it down to 25" no problem. I plugged it back in and with a crap load of pumping with the MightVac it pumped down to 20" and seems to be holding. I'm going to let it sit there for a while and see if it held.

drivinfaster 10-02-2012 06:38 PM

some rtv around the grommet may help. at least until a new one can be delivered.



df

dc_wright 10-02-2012 07:05 PM

Held for 20 minutes no problem. I'm going to order the grommet, the one way valve, and the hose and see if that does the trick.


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