Here are some pix I took while replacing the diaphragm in my old type (two line) vacuum pump. This was in my formerly owned 79 300D. I removed the radiator, only because I had to anyway. It went to the radiator shop. I also pulled the condenser, I planned on doing that while the radiator was out. That's because the compressor is long gone and I have no plans on reviving the AC. Remove what ever you have to to give yourself enough room to work in there.

The instructions that came with the diaphragm rebuild kit said to remove the pump from the engine. That is not true with these old style diaphragm type pumps.

1) vacuum pump still on the engine with front plate & diaphragm removed. Basically what you do is remove the flat head screws that hold the front plate on. Do so in a cross pattern, not in a ring pattern. Then give it a pull and it will come off. Behind that there is a center bolt, it is a hex head, I forget the size. Undo that, then the center bolt, diaphragm, disks etc. pull straight out as one unit.

2) Front plate, removed, vac lines still attached. sitting up top, and out of the way. The check valves are in here. Behind the "diamond" shaped cover. I did not rebuild this part of the pump. Although there is a kit for it. From the symptoms I was describing to my indy parts desk (little bit of oil in vac lines. small pool of oil in air cleaner) I was advised that the diaphragm should do it. Note the black mark around the lower right screw hole, this is where the oil was seeping out. There wasn't really a tear but oil was getting around the diaphragm there.

3) Top view of pump. Keep in mind that the front plate and diaphragm are removed. Note radiator , fan shroud and PS belt are removed.

4) Diaphragm (removed) with center bolt and disks still attached. This is the front view or the side that faces the front of the car. Note that the smaller disk goes on this side, rounded edge toward the diaphragm. You'll want to clean up any oil in the front of the pump (rear of the front plate) also clean the front disk. Basically all the oil is supposed to be behind the diaphragm, only air/vacuum in front of it.


5) Rear side of the diaphragm, or the side that faces the engine. With disks still in place. Larger disk goes toward the engine, rounded edge to the diaphragm. The kit came with a new diaphragm. It also came with a new center bolt, a dab of blue loctite (for the new center bolt) and half of the screws (flathead) needed to replace them all. Go figure.

Hope this can help anyone who needs to rebuild a diaphragm vacuum pump!

Follow up: I've read that some people have had their new diaphragms fail. I think this is because they put the disks in backwards. Or overtighten the new center bolt. Be sure to put the rounded edge of the disks against the diaphragm itself. Mine is still holding up. (9/12/07)

Attached Thumbnails

         

__________________
Sonny


86 190D N/A 2.5L Auto 265k "Ruby" -Sold-
79 300D 242k "Condi" my first -sold- RIP
2013 chevy sonic hatchback - had to for work