1983 Mercedes Benz 300sd Vacuum Pump

PACBISHOP

MEMBER
1983 MERCEDES BENZ 300SD

Brakes problem
1983 Mercedes Benz 300sd Two Wheel Drive Automatic 200 miles

Typical vacuum problem. I have changed the booster and booster line and have intermittent brake operation. I disconneted the booster hose from the vacuum pump and get good but intermittant vacuum. Can the vacuum pump operate intermittantly? What is the fix?

2 Replies

MHPAUTOS

MECHANIC
31,937 POSTS

Hi there,

The vacuum pump should work constantly, you will need to have it overhauled.

Mark (mhpautos)

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Tuesday, November 11th, 2008 AT 9:29 PM

DIESELLOVER

MEMBER
13 POSTS

Agree 100% - vacuum pump operates fully all the time. However, the first thing I'd check is the condition of the diaphragm. There's a small "door" held on with 2 screws on front of the vacuum pump. Take off the door and look for a tear, however slight in the rubber piece there. It's very inexpensive, and very easy to replace and quite often with age, can be the problem. If it is the cause, it takes 10 minutes +/- to replace and will work like new when you close it up. Hope that helps!
Best wishes,
Tom