Got dem ol leaky oil pump blues

[breaze]

I've seen this topic many times, but the solution is always a new pump. I've got a pump off an 87 SE50 which I would like to use but it does have a slow leak as I recall - daily riding no problem but after a few days sitting, starts to smoke.

Best I can tell from perusing leaky oil pump threads, there doesn't seem to be an obvious reason these pumps begin leaking. Is it possible that replacing the rubber seal which the pump shaft goes into might help - creating a better seal? Or does the leak more than likely come from somewhere else. I've taken apart a few old pumps just to learn and never found an obvious reason for leaks.

Has anyone ever replaced that seal? Any idea how to find one the right size? I've got a couple of old pumps and I'm going to play around with using a different seal (from another pump) in the one I know leaks. Seal comes out easily enough - just held in by a small metal clip/ring...

[Red Eft Performance]

Is it really hard to start when its been sitting a couple days?

[breaze]

Once again, this is based on recall (sold my old SE50 a couple years ago with a new pump in it and kept the old pump). But, as I remember, it was harder to start the longer it sat - but that could be said for most every scooter I own.

I just got another SE50 and the pump is crusty - so I'd like to use this other one if I can stop the leak.

[mousewheels]

Or does the leak more than likely come from somewhere else.

I've had four of five bad oil pumps on various Gyros. All have leaked through the pump to the outlet from sitting. Never had a seal issue.
I recommend folks with bad oil pumps to run this test:
Place the assembly with the inlet connected over a container at the drive end and another at the outlet.

The pump outlet failure can be from a check valve leak. The brass fitting the outlet tube connects to is a check valve. It is lightly spring loaded to hold off static pressure of the oil tank, but opens during the pump stroke itself.

For Gyro's where oil pumps are difficult to find and expensive once found, it's been worthwhile to remove a check valve from a low cost pump like a Spree to use as a replacement.

Any idea how to find one the right size?

I got the size from a Spree pump seal (it was marked right on the seal , here are some sources:
Sources for the exact seal - 9.5mm x 16mm x 4. Shipping's driving the price up... Here's the links if any need a seal right now:

http://www.mfgsupply.com/m/c/501415.html $3.99 + 6.99 ship

http://www.gokartsrus.com/80049-oil-sea ... -2157.html $2.85 + $15? min shipping/handing

[breaze]

Thanks Mousewheels - extremely helpful as always

[maddog]

The only part you can change on a oil pump is the o-ring, my sa-50 oil pump went stock/ bore kit for 50,000 mi. i did a sym pump swap along with a shaft swap.