Vacuum Pump - Rebuild Kit
 

My '83 300SD vacuum pump went south, so I purchased a rebuild kit (manufactured by Meyle) from ******** here on Phoenix.

Are there any specific online instructions for the rebuild procedure? I'm amazed at how few parts are in the rebuild kit. How does the pump function? I got the impression that the pump operates via a diaphram, but all I see in the kit are what appear to be 3 small diaphrams. Also a brass check valve housing, but no ball within the housing.

Any advice will be appreciated.

The Factory Manual has rebuild instructions; at least for my car.
The 3 diaphragms are valves.
There are several models of Vacuum pumps single diaphragm, double diaphragm and the piston ones.
There is 2 rebuild kits for the Piston type Vacuum pumps. The one that you have and an expensive one that replaces the parts on the drive end of the pump. If you buy both it cost more than a new pump.

Your version of vacuum pump is probably the same as mine. IIRC, there are two small check valves, two spacers, and a large o-ring for the piston (instead of a diaphragm). I think even the gasket was separate.

When you do the rebuild be very careful to note how you remove each piece, which side is up, etc. The replacement of new parts is just a reversal of the procedure used to remove the old ones. You should be able to do this even if you cannot find a service manual.

Jim W.

On some kits the O-rings that go under the check valves are not thick enought to seal. Several Members have reported this.

I came across this and found that there are two versions, depending on VIN series, an earlier and later. The later series had some type of plastic spacer rather than the o-rings. Since mine were in good shape, I just reused the original spacers.

'83 300SD - Vacuum Pump Repair Kit from AutoHaus
 

Thanks for all the info. I used the subject kit, and everything worked out just fine. I did the repair with the pump still in place after swinging the power stearing pump out of the way; a little akward at times, but manageable.

My pump uses 3 tiny valves (diaphragms) each about the diameter of a dime - 2 near the pump bottom and one on top (pointed into the check valve galley). It's imposible to get the bottom valves in backwards (the pump front plate won't allow clearance), but I managed to get the top valve in wrong with the result that the pump didn't create vacuum. I finally spotted my mistake, reversed the top valve orientation, and now have all kinds of vacuum. In fact, the vacumm is so high it collapses the "mityvac" tubing!

I immediately found that the power brakes worked normally, but the engine still ran on for several seconds after turning off the ignition key. But, for some reason the engine now shuts off normally since I have driven for 20 or 20 miles. Also, the problem of hard starting after shutdown (only while the engine was still warm) has disappeared. Anyone have ideas as to why those problems disappeared after a short period of driving? At any rate, I'm crossing my fingers that everything continues to work well.

Thanks again for your help.

Vacuum Pump rebuild
 

Search for write up by Stevo. Very good instructions. I did mine on a 1985 300sd last weekend.