Rotory vac pump not working, oil pumps fault

[rabbitman]

I bought a vane pump a little while back and installed it the other day but it wouldn't make any vacuum, and after trying it for a bit it started making aluminum shavings inside it.

So after messing around forever I discovered it isn't getting oil up in it. I spun the oil pump with a drill and it intermittantly pumps oil out the oil shaft. Sometimes I'll spin it and no oil so I spin it backwards for a second and then forwards again and it'll pump lots out.

The oil pump is a heavy duty one from myke_w a couple years ago and the vac pump worked on the previous vehicle.

Any ideas?

[rabbitman]

Ok so I tried more stuff, neither the vane pump out of the golf nor the one I just bought work in the rabbit but BOTH work in the golf.

Sounds like an oil pump issue huh?

What would be the fix for such a weird problem?

Has anyone else ran into this?

[rabbitman]

Yup I checked the screen and the seal, they're both good.

Interesting, I thought the oil went directly from the gears straight up the shaft.

So there should be no way it could intermitantly pump out the shaft end then I guess but it sure didn't everytime I spun it. I'd spin it for a good 10 seconds with no oil coming out the top, the inside of the socket would stay clean. So I'd spin it backwards for a second or two and then forward again and then it'll soak the socket and come up between the socket and extension.

[rabbitman]

Could the shaft bushing be turning in there?

[rabbitman]

I suppose it's possible and if it was it would cause the intermittent pumping up to the vac pump.  Oil would only flow when the hole in the bushing aligned w/ the hole in the block.

Wriggling the oil pump shaft should show a bad bushing right? So I don't have to take it all apart and measure anything.

I just made a new diaphragm yesterday so I should be good for a couple months at most and I'll mess with it then. My last bought diaphragm lasted a week and tore, upon inspection I think I put it in backwards with the hump facing the wrong way........and on top of that one of the plates that go on each side of it was in backwards with the sharp lip cutting into the rubber. I was getting ready to go on a trip so was in a big hurry..........

[theman53]

I have a brand new diaphram pump rebuild kit as I bought it thinking I could fix the one I had. New in package yours for shipping cost only. I have both packages for rebuild.

[rabbitman]

I have a brand new diaphram pump rebuild kit as I bought it thinking I could fix the one I had. New in package yours for shipping cost only. I have both packages for rebuild.

Thanks I'll keep it in mind. Ideally I want to go to a vane pump, if it proves to be hopeless I'll probably look for a rubber material that will last longer than what I've be making them out of and just go with that. If I can cut the costs to way below factory parts I'll just do that, I can make and change it in a little over a half hour unless I mess up and have to start over. So if I crank out 10 in one sitting they're pretty fast to change so it probably wouldn't drive me too crazy.

[rabbitman]

So in changing my diaphragm yesterday I discovered the sliding shaft with the nylon bushing is very worn and sloppy, I distinctly remember it used to be a snug fit so my guess is it's not getting oiled properly.

I'm thinkin' the problem is the oil pump shaft bushing but still have to check and make sure, I looked at all my regular online stores but couldn't find the bushing, anyone know where to buy it?

[R.O.R-2.0]

So in changing my diaphragm yesterday I discovered the sliding shaft with the nylon bushing is very worn and sloppy, I distinctly remember it used to be a snug fit so my guess is it's not getting oiled properly.

I'm thinkin' the problem is the oil pump shaft bushing but still have to check and make sure, I looked at all my regular online stores but couldn't find the bushing, anyone know where to buy it?

all my rotary pumps have play in the sliding shaft.. none of them are tight.. the diaphragm holds it in place.

[rabbitman]

I wish I had another one to look at, I'm sure I remember that it used to be almost zero slop in it.

Every time I change the diaphragm the vac pump is full of oil which leads me to believe the oil pump is working properly at least part of the time.

[fatmobile]

No oil pressure gauge?

[rabbitman]

No oil pressure gauge?

Yup, I get about 90psi cold idle and 30psi hot @ idle, cruising at 3000rpm hot is about 50psi.

It seems the problem is that oil pressure isn't making it's way out the top of the oil pump drive shaft 100% of the time.

[rabbitman]

Could the shaft bushing be turning in there?

That was a total guess but it is in fact what was happening.

I pulled my rotory pump today to see why my brakes are hard to push and the diaphram was fine. But while it was out I reached my finger in there and turned the oil pump and HA, the bushing turned too .

So I got a picker and reached it in and working the bushing little by little I got it out.


The OD of this bushing looks almost perfect, one side has a little bit of scuffing is all so I think the bore in the block must be worn.

Now what are my options here? I'm not a machinist, but I might have access to a shop with all the tools needed to make a new one. Or I could measure it real good for future use and then knurl it and pound it back in the block, the inner bore isn't perfect but by no means worn out.

Anybody wanna make some?

[theman53]

If I had that part and or some specs I could have an amish machinist pound some out. He works good and cheap.

[rabbitman]

If I had that part and or some specs I could have an amish machinist pound some out. He works good and cheap.

                                     OD:     .8279
                                 Lip OD:    .9931
                         Total length:    .8183
                            Lip length:    .0993
                               Hole dia:   .25
Bottom of lip to center of hole:   .279
                ID of worn bushing:   .554
        Used oil pump shaft dia:    .5528

You can see in the picture the two thrust surface oiling grooves, they are about .005" deep. The oil pump shaft diameter is a TINY bit smaller where the bushing sits (due to wear) but it wasn't really measureable with my micrometer, I could just feel it get slightly looser at that point.

I can't guarantee that these sizes will work for any engine though, after all it worked loose in mine. I don't know if it's supposed to be a really tight press fit or just slightly tight.