I replaced the diaphragm on my vacuum pump about a year ago. last week it started leaking oil from the lower outlet,I was angry thinking the diaphragm was the problem,I was thinking they sold me a fake Meyle brand part. so I opened the pump and the diaphragm is fine, I cleaned and inspected all parts and tighten the pump better because I thought it was a little bit loose, I put it back and tested it at idle at it seemed fine. I took it for a spin around the block and when I came back the leak was back ( Heavy leak ) engine bay messy again. I bought another used vacuum pump, checked it and lubricated it a bit put it in the vanagon and now is fine.can someone tell me where that outlet is suppose to go? I have a MK2 engine in my vanagon with the block opening pluged, is that outlet suppose to leak a little oil or only air i have it open to the atmosphere. what is making the pump leak? could it be the check valves, maybe the small seal in front of the Little piston in the back of the diaphragm?
Thank you for any help you can provide.
Felipe
PS: I read all I could find about vacuum pumps on the forum already.
I don't use those vacuum pumps, I use the kind from mk2 where the top hose goes straight to the brake booster.
mk2 engine came with a block plate, the mk1 had a plate with a nipple to connect to the other end of the older vacuum pump.
I use the mk2 type and put an extra breather hose from block barb connection and t it into the intake, because I have read people do that to help relieve pressure.
Yep use the mk2 vane pump and it'll last 80 years, there being 3 spare edges per vane, and each one lasts 20+ years!
Thank you for the input,but can someone answer my question about the old vacuum pumps? now I have 2 of those and the diaphragm kits for them,and even the check valve kits that are not easy to find.I'll try to get one vane type pump when I can, meanwhile I'll use what I have, when they work they are fine, but you know you have to fix them every 2 - 3 years.
The outlet is supposed to go to the crankcase breather. There shouldn't be oil on that side of the diaphragm at all. There is an o-ring that's supposed to seal the shaft. Is that possibly not installed correctly?
Are you sure it is leaking oil from the outlet of the pump? Could it be leaking from the seal at the base of the pump? Is it possible you're drawing brake fluid from the booster (easy to check if your brake fluid is going down)?
Yes, it was leaking from the lower outlet, I think the leak is caused by the o- ring like you mentioned.when I replaced the diaphragm I don't remember if I changed that o-ring, I think I did, but when I checked it, the o- ring was kind of loose around the shaft. I did not think it should be oil on that side of the diaphragm but I wasn't sure, thank you for the information.