Been discussed before I know. Oil leaking from vent on bottom half (not inlet or outlet). the one that has the pipe which normally is tucked through the grommet in the undertin. Why would it leak from there. Its on level ground! Its done it before when the van has been on ramps but seemed to only happen then but now its dripping quite a bit. Looking at the diagram in Haynes the bottom half is beneath the diaphragm and the lower half should contain, or be packed with grease, there isn't a seal as the pump lever extends into here to operated the pump rod. Of course it will have to come off to sort the issue but why would it do this now? Ideas?
I if it isn't the bakalite gasket/spacer that is cracked, then the pump has had it! I fitted a repro unit from Heritage a couple of years ago and that leaked too. I know they stopped selling them and have now restarted, but I have no idea if they are any good. ..I ended fitting an electric pump.
check for fuel in the oil. my son had this problem on his T25 2l cu engine. We wasted money buying a repro pump which was no good. Went electric pump with safety relay, sorted.
The pump has a pushrod poking out of the engine block which is driven by the camshaft. Here's a photo of what it looks like with the pump off. You can see the push rod and a hole in the bottom of the casting. This is to allow oil to drain back into the sump I've assumed, but I guess it could fill up directly on a slope if the engine had been overfilled. I imagine oil can also come through if the push rod is worn, though I put a genuine new one in recently. This cavity is normally filled with grease, as is the rest of the base of the pump, but I'd assume oil can reach the base of the pump if there's not much grease there. I've been more bothered of late with oil leaking at the bakelite spacer. I cut new gaskets and also sanded the surfaces flat on 800 grit. OK so far though I've not been able to do many miles.
I don't believe that cavity should be filled with grease, or the spacer. How could that cavity drain if it were filled with grease? The base of the pump - yes and maybe it's gone awol or someone used a grease that's been dissolved by the oil - there are some really poor "medium" greases about. Castrol for the win. Have a sniff of whatever's coming out though, if the diaphragm is damaged it could be petrol. VW could not have got away with selling vehicle that leaked oil when parked on a slope, they'd have been laughed at.
You're right about the grease. Bentley says use universal grease on the pump and molybdenum on the push rod. I have previously overdone the push rod so oil wasn't draining back. That hole needs to be kept open.
Am sure I’ve got one kicking about that I took off when I went electric. Let me know if you’re interested I’ll go have a look for it.
