Topic: Oil pump leak stopper valve

[Kevin D]

 I was cleaning the oil pump screen and noticed that the piston for the leak stopper wasn't seated in at the end of the bore. The piston left the port below the knock pin wide open. I took it out and found a tiny burr at the bottom of the bore. I think the piston is supposed to travel to the end of the bore and block the vertical port where the knock pin sits, yes??
 
 I'll be getting my 220 and 600 grit out to smooth the bore, but I don't sure want to muck it up as I've heard that oil pumps might be unobtainium.

I believe this is the gadget that holds the oil back in the tank when the motor is shut down.

[Sweep]

I dismantled my oil pump today and yes the hole is blocked completely by that piston and all I can see is the side of it.

[750goes]

the oil pumps are not that hard to find... the little rubber seal that sits inside the end of the piston is not available to my knowldege....
the spring pressure on this is very light and it needs to slide smoothly to stop  the WET SUMPING that can occur if the rubber seal is knackered.

I would not be too over enthusiastic on the entire piston to take off that burr, only where the burr is located.. seems a strange place for a burr to be located also - has this ever been apart before ?

[Kevin D]

The rough part is inside the casting, piston is OK.

WET SUMPING

Yes, it takes about a week to empty the oil tank.

also - has this ever been apart before ?

Yes, by me, a loooooong time ago.

Also noticed the adjacent knock pin doesn't slipfit down into the casting. The casting isn't milled out and the knock pin just kind of sits there on top.......a little higher than the other two.......maybe it pushed the casting down into the piston........ doesn't quite add up but I guess I'm lucky it was stuck open and not stuck closed.

I think I'll do a test assembly, smooth the bore and maybe shorten the knock pin

[750goes]

Just maybe, a bit of metal or debris got through the pump assembly somehow and lodged in the bore, then just happened to get stuck between the piston and bore when the valve closed and caused the burr , maybe this jammed it open..... good find though..

[Jonesy]

Before you shorten the one pin, reassemble the pins into the pump and hold the pump in place in the crankcase with no O-rings. if the pump seats tightly against the case, it should be OK. (I remember a little bit of play in these bores, with the bores being slightly longer than the pins so they can "float", but I could be wrong).

Also, is the pin damaged at all? Roll the pin across a sheet of glass and look for any wobbling. If the pin is damaged your best bet is to replace it. Just a thought, in case it may have gotten cocked during the last reassembly.