Chainsaw oil pump issue confused

[nath7241]

Hi, new to the forum but thought i would jump right in. I have just got hold of a 1996 partner 370, it all runs fine, but the oil pump keeps pumping the oil out long after the saw is shut down, leaving quite a mess, i have changed the oil pump and lines, also flushed out the tank, but it is still pumping oil after its turned off, and can continue to do so for up to 15-20min, the parts i have not changed due to having trouble finding them are the worm gear, tank vent. I am not sure how these will cause this problem though, the worm gear stops when the saw is off and any issue with tank vent should surly decrease oil ?

not the end of the world as i can just empty after each use but i would love to know why this is happening. any help would be fantastic thank you.

 

[Egg Shooter]

Hi, new to the forum but thought i would jump right in. I have just got hold of a 1996 partner 370, it all runs fine, but the oil pump keeps pumping the oil out long after the saw is shut down, leaving quite a mess, i have changed the oil pump and lines, also flushed out the tank, but it is still pumping oil after its turned off, and can continue to do so for up to 15-20min, the parts i have not changed due to having trouble finding them are the worm gear, tank vent. I am not sure how these will cause this problem though, the worm gear stops when the saw is off and any issue with tank vent should surly decrease oil ?

not the end of the world as i can just empty after each use but i would love to know why this is happening. any help would be fantastic thank you.

Pop the oil reservoir cap off after use to vent it. See if that works. The tank vent should only let air in. Heat from the engine is probably pressurizing the tank some. Happens a lot on some of my vintage saws but those are pulse driven and pressurize the tank by design. If I don't vent them they spew oil long after shutdown.

 

[nath7241]

Thanks Egg Shooter, will give that a try when home, never thought about the heat causing pressure only thought mechanical fault ha.

Thanks Again.

 

[Cooper264]

This is a tricky one. I have heard guys say that some when they are turned off, it can create a siphon, when heated oil expands or contracts it somehow creates pressure in the tank, a one way valve on some filters gets messed up or something, if you turn the saw the right way it perfectly lines up the lines and such and yada yada and drains the whole tank.. I haven't been able to tack down a definite reason as to why it happens. In my opinion, if the oil system is 100% completely as it should be, meaning pump, lines, filters, grommets, everything, there should only be a small amount of oil that comes out of the saw after it has stopped. And thats just the oil that has been slung into the clutch cover assembly and around the bar while running that comes off. Now if you hang your saws, i'de say some sort of oil may come out of the lines or pumps. I think that is just a saw to saw kind of thing

 

[nath7241]

i agree, if everything is as should be then it should not continue to pump the oil, i doubt it would have done this from factory, i think it is the air inlet valve, i disregarded the air inlet valve, as on my previous saws if these are damaged or faulty it dose the opposite and builds vacuum that stops the oil coming out at all, but i was thinking could there be just enough resistance on a valve to let a small natural vacuum hold the oil in once the gear worm stops turning the pump, then when the saw runs and the pressure increases to a higher amount it pulls the air back in, etc, so i ran the saw, turned it off, waited 5 seconds then put some putty over the valve and left it, there was a slight pool of oil which could be residual, but nothing like before, so i have finally found a new valve and ordered it and hopefully this will solve it.