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  #1  
Old 12-19-2015, 04:42 PM
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Join Date: Sep 2015
Location: Tacoma, WA
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Post '78 240D Brake Booster Test/Question

Hi Folks,

I've got a really hard brake pedal on the 240D lately, and am trying to do some tests to verify it's the booster or not. One test I did was to disconnect the vacuum like to the booster, then draw a vacuum directly on the booster with my vacuum pump. I can get it to pump up and hold 15hg (before my hand gets tired), but when I put the slightest pressure on the pedal (like 1/4"), all the vacuum drains out very quickly.

Sometimes it takes a while for the engine to shutdown, but I think I found a correlation between that issue and touching the brake pedal. I recently replaced the MC and put the new gasket in...that was working great for about a month. The booster had a lot of fluid in it at the time I replaced the MC, and I sucked as much out of there as I could.

Sounds to me like the booster is done, but wanted an opinion from you guys before I bit that bullet.

If I do bite that bullet, any thoughts on reman vs. new? Seems like reman would be fine.

Thanks!

JC
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1978 240d Automatic
1977 F-250
1966 VW Bus
1963 Thunderbird
1979 Audi 5000
1970 VW Bus
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Old 12-19-2015, 05:18 PM
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Join Date: Jun 2004
Location: Southeast Wisconsin
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It sounds to me like its done too. You had a master that leaked fluid in it, and that fluid did in the booster. Pretty much what you suspect.
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Old 12-19-2015, 05:49 PM
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Awesome. Thanks for the confirmation.
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  #4  
Old 12-25-2015, 06:30 AM
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Join Date: Oct 2015
Location: Geneseo, IL
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I just did the exact same thing on my '78 240d. Replaced both the MC and booster. I used a reman. Shoot, the MB part was over $600, which is almost half what I paid for the car.

BTW, if you post questions like this over on the diesel forum you'll get a lot more response.
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1978 240D
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