Rebuilt my Vac Pump, Now.......
 

I got brakes that take at least 2" of pedal before they start to stop the vehicle.

The only difference between before the change (only about 1/2" before they grab and stop) and now is that pump kit.

Do I need to bleed them or something?

Just doesn't make sense to me.....

This is on the 300SD....

I have been going round and round with some of the same issues. I did a search today and read where some other members found that the little O-rings that fit under the 3 check valves are smaller in the rebuild kit than the original ones. Their solution was to reuse the old small O-rings and their vac problems cleared up. Unfortunately I threw all of that out but I do have a metric O-ring supply so hopefully I will have some that will work better.:mad:

I read those posts also, and I checked the different parts, they were all the same size, so I'm not sure that this qualifies for the other fix.

I'm going to try doing a brake bleed just to see if it helps. I can't believe that it will, but it's worth the try.

I can't imagine the fun I'll get to explain after I do the AC Compressor, Drier and expansion valve ! ! !

Hmmm.......that's strange. Do you think it is possible to have installed one of the little check valves upside down? Of course, that might give you no vacuum at all. I,m not sure what the symptoms would be if that happened. Did you put a vacuum guage on the system to see what you are pulling now?

OK, I'll be Obvious Man. If it didn't do this before the rebuild, but does it after....... Something went awry. It never hurts to bleed the brakes, but that would really be surprising if it solved the problem.
Having said that, stranger things have happened.....

On your AC stuff, it isn't as hard a you think. Although, I have heard horror stories about attacking that W126 exp. valve....:eek: :wallbash:

Thanks everyone....since I still have brakes and it's just an adjustment on my part, I'm not going to worry about it right now....

Just suggest everyone stay behind me! :)

Soft pedal, poor stopping power = air in brake lines
Hard pedal, high pedal pressure reqd for stopping = low/no vacuum to brake booster or defective/leaking booster.

Fuzz,
I recommend that you check the big vac line that runs from the vac pump to the booster for cracks...easy to damage that unit, especially when it's OEM and 25+ years old.

It makes no sense, how would messing with his vacuum pump do anything at all to the brakes, such as getting air in the lines. The problem lies either with the vacuum pump, or the connection between it and the brake booster. I am guessing the pump. Check its vacuum pull, it should be about 28".

Remember that only the pump was worked on, the brakes were not part of the task.

Update
 

If you are still having problems with the vac pump take it apart and use some motor oil to slick the sides of the cylinder. Just take off the front and wipe it down. Also check the check valve on top, the one that didn't come with the kit. I did mine like that and it started working like it was suppose to.