Thread: 300tdi vac pump- this is it's insides.

As with some 300tdi's, the vac pump sometimes leaks engine oil. I was able to get another leaky one for the purpose of finding out what makes it tick. Using a 4.5mm drill, I weakened the rivets so the ends could be nipped off with a pair of needle nosed pliers. I used a a small pair of vice grips to hold the head of the rivet so it wouldn't spin whilst drilling. Then the cover can come off easy.




And there are the bits. The diphram in the body of the unit was ok, as were the valves in the face. There didn't appear to be any damage to the o-ring, so I can only figure that the rivets on the bottom had given up over time. There will always be some oil in the bottom of the pump, and excess gets sucked back into the sump - the exhaust valve to the sump is the hole on the right on the plate and the hole at the bottom of the pump body. As to repair, I was going to try cap head bolts, and either nylocks, or a tap to thread the holes in the body.

A couple of tips: 1. Remove the pump with the engine at TDC - the spring inside is very stiff.

2. DO NOT HIT THE PLUNGER WITH A HAMMER TO TEST THE SPRING- this is what happens when you do that:



I'll do a follow up when I reseal it and do a leak test.

Question: Has anybody ever tried this before?
I was able to find a kit for a Merc vac pump, very similar except on of the ears (things on the side of the o-ring) was a double.

Unfortunatly Wabco made the pump so you can't use ordinary o-rings to replace it's OEM one. There's no space between the inlet/outlet and the main o ring.

So there you go.( And yes I stripped the paint off it with paint stripper)

UPDATE: I followed Ace's method, website as stated below, and it WORKED A TREAT. All that was required was to buy a sheet of oil proof jointing material-$8 A4 size sheet, and make your own gasket.M5 cap heads 15mm long with nylocks to top it off.

ALL HAIL ACE !

Can I display my ignorance and ask what a vacuum pump does exactly? Something to do with the brakes?