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E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 12-14-2010, 11:59 PM
cmac2012's Avatar
cmac2012 cmac2012 is offline
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Location: Berkeley, CA
 
Join Date: Nov 2005
Posts: 3,408
Mein Auto: 1987 325i, 386K
Brake power assist cut out

Latest episode in the ongoing saga of "this Beemer's gonna make a man out of me yet." I put in an ATE master cylinder, decided against trying to disconnect the ABS - instead bought the ABS unit. Sorta like building a ship in a bottle. Finally I got everything in the right place and actually threaded proper. Bled out much foamy fluid. Brakes are much smoother than before (new rotors and front calipers also) but somehow, I deleted the power assist in the process. Braking pressure felt the same when I shut the engine off at 50 mph and coasted and braked.

No vacuum leak that I can detect. For the heck of it, I took off the oil cap while it was running, just to remind myself of what the engine does with a major vacuum leak. Ran very rough, of course, and smoothed out nicely when I put the cap back on. I sprayed brake cleaner in the area where a vacuum leak might have been created on the power assist unit by my large clumsy hands - no change.

I know that I carefully put the new gasket on the master cylinder before installing.

Somehow I have angered the Gods. There's no other explanation.
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Last edited by cmac2012; 12-15-2010 at 12:01 AM.
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  #2  
Old 12-15-2010, 08:37 AM
markseven markseven is offline
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Location: John 3:17
 
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Mein Auto: BMW M Power
Quote:
Originally Posted by cmac2012 View Post
Latest episode in the ongoing saga of "this Beemer's gonna make a man out of me yet." I put in an ATE master cylinder, decided against trying to disconnect the ABS - instead bought the ABS unit. Sorta like building a ship in a bottle. Finally I got everything in the right place and actually threaded proper. Bled out much foamy fluid. Brakes are much smoother than before (new rotors and front calipers also) but somehow, I deleted the power assist in the process. Braking pressure felt the same when I shut the engine off at 50 mph and coasted and braked.

No vacuum leak that I can detect. For the heck of it, I took off the oil cap while it was running, just to remind myself of what the engine does with a major vacuum leak. Ran very rough, of course, and smoothed out nicely when I put the cap back on. I sprayed brake cleaner in the area where a vacuum leak might have been created on the power assist unit by my large clumsy hands - no change.

I know that I carefully put the new gasket on the master cylinder before installing.

Somehow I have angered the Gods. There's no other explanation.
Check the hose that connects to the booster - it may have a tear or something?
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  #3  
Old 12-15-2010, 08:42 AM
Pennyw1se Pennyw1se is offline
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Mein Auto: 1988 325e
And hope you didn't get any brake fluid into the brake booster.
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  #4  
Old 12-15-2010, 02:22 PM
monkeytaco monkeytaco is offline
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Location: Denver Colorado
 
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Mein Auto: e30-318i
And make sure you reinstalled the check valve in the correct orientation?
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  #5  
Old 12-15-2010, 11:53 PM
Billwill Billwill is offline
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Location: South Africa
 
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Mein Auto: BMW E30 318i 1991
If you press down on the brake pedal and start the motor, the pedal should go down slightly....this shows that there is vacume present and the servo diaphram is doing its job.
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  #6  
Old 12-16-2010, 01:51 AM
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cmac2012 cmac2012 is offline
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Location: Berkeley, CA
 
Join Date: Nov 2005
Posts: 3,408
Mein Auto: 1987 325i, 386K
Thanks for the help - I'm afraid I wasted your time. I was too anxious . . . or something. It sure felt stiff, a bit heavy. I was on a lonely stretch of highway so I got it up to speed and tried braking with the engine running and then off, seemed the same.

The new front rotors got a bit rusty in the moist weather we had in the two days it sat up on stands while I was waiting for my parts guy to come to work Monday morning. Maybe the rust and the newness of rotors and pads made it feel heavy, I dunno. After posting I tried the test Billwill spoke of - it was right there in my Haynes manual - and it did go down a bit after I started it.

Seemed better the next day, dunno why.

After I've put in some time on some job like this and I take it out for the first test drive, I'm like a diva who thinks she might be coming down with a sore throat.
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Last edited by cmac2012; 12-16-2010 at 01:53 AM.
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