[PARKWARD]

Hey mates...hopefully you can help me diagnose this problem. I have reviewed the Brake booster tips etc prior to posting this. Here goes... just had my mechanic change the rotors/pads/master cylinder and reservoir on my 1980 300 SD. Now never had a problem prior to this with vacuum or brake booster..the engine will not shut off now on its own...the pump is sending necessary pressure to the brake booster...HOWEVER...very little pressure is leaving the brake booster..hence brakes are hard and the engine stays running..could there be something my mechanic had done incorrectly when he installed the master cylinder? improper seal perhaps?? Any suggestions...NEVER had any of these problems prior to him changing the master cylinder out. Most greatful for any and ALL suggestions. Thanks mates! CHEERS!

 

[jzchen]

In my '85 300D I had a problem with no brakes. It was really difficult to stop. Since practically everything vacuum related, ie door locks and turning off the car stopped working, I ended up changing the vacuum pump, brake booster, and while I was at it the master cylinder. (This might have been overkill...)

I'm not sure I understand what you mean by brakes are hard. Does this mean they are now working well, or are not working well? I suspect you had a braking problem like me so that is why the master cylinder was changed. I'm afraid I suspect the brake booster.

 

[PARKWARD]

Exactly..the braking doesnt have power assist now...the curious part about all of this. I have had NO problems with the car of this nature...could it be the brake booster just gave away at the same time as the master cylinder?? Or did something get put on incorrectly??

 

[liammarsh]

You can test the brake booster (assuming it is the same on a w116) by disconnecting the booster line and applying vacuum to the booster at that point and see if it holds it.

 

[jzchen]

Just curious, why did you replace the master cylinder? Was it leaking? I don't think I needed to replace mine. I just did it because I already had to take it off to get to the brake booster, (and because I found one with a lifetime warranty.) I figure it would last longer than if I just put back the old one...

(Read as I hope you didn't replace it unnecessarily.)

Yes, you can test the brake booster, but you kind of have to make the attachment/tool to connect to the brake booster fitting. I just said might as well just change the booster and vacuum pump instead.