1940 chief sumping

[jn1972]

I am having trouble with my 40 chief sumping ,I had the motor rebuilt about 4 years ago and the oil pump was rebuilt at the same time ,it just started the end of last year ,if I do not start the bike every 2 days it will sump . Does the oil pump need to be rebuilt again ? Thanks Jerry

[Lipdog]

I just went through this on my ‘48. You may get lucky by taking the pump off and replacing and reseating the check ball and spring. But it didn’t work for me. I bought a new pump from Kiwi and it fixed the problem. I can let it go two weeks and start it without sumping. But due to the design, a little oil still gets by. I’d say if I let it sit two months, I’d probably drain the sump before starting it.

[hairynob24]

cast iron pump is different beast to alloy one no check ball n spring , not sure why the cast iron pump would wet sump if it has been rebuilt ? did you put the oil pump on ? if so did you install the felt washer n spacer in the cam cover where the pinion feed is ? my 45 started to wet sump n I had not installed these pieces ...

[tfburke3]

I dont think the felt seal matters for leaking to sump.A good seal would just direct the leak to the crankpin instead of the pump housing.
I believe building up the plunger and fitting to proper clearance is the only solution.I dont think oversize plungers are available.
I would probably contact Kiwi or Dinihanian who both have adds in mag,or look for a nos pump.
Tom