firebox40dash5
ArboristSite Member
The adjustable oil pump on my MS260 Pro decided not to work yesterday... it wouldn't put out squat for oil (though a tiny bit was flowing out from the output), and the control bolt would just spin and spin rather than only turning 1/4 turn or so.
I took it apart this morning, and figured out that the control bolt had backed out of its bore just enough that the 'head' that keeps it from turning too much cleared the nub on the pump allowing it to turn freely, and enough that the pump shaft end was riding on the eccentric that adjusts the flow, rather than riding on the tip of the bolt like it should be. I removed the roll pin that holds the control bolt in, cleaned everything up good, and reassembled it the way it should be... and it works great. The problem is there's nothing keeping it from happening again, the groove in the control bolt that the roll pin goes in is wide enough that it can just work its way down again. The more I thought about it, I realized I've had low oil flow ever since I bought this saw new in '03. Even now, it's just enough oil for my 16" B&C when turned all the way up.
Has anyone had this issue before? I'm wondering if this has happened over time, and would/could happen to the new pump if I replaced mine, or if my oil pump was just messed up from the factory, and that's what caused my low oil flow the whole time. Do any larger oil pumps (maybe from an MS360 or 361?) fit the MS260?
I took it apart this morning, and figured out that the control bolt had backed out of its bore just enough that the 'head' that keeps it from turning too much cleared the nub on the pump allowing it to turn freely, and enough that the pump shaft end was riding on the eccentric that adjusts the flow, rather than riding on the tip of the bolt like it should be. I removed the roll pin that holds the control bolt in, cleaned everything up good, and reassembled it the way it should be... and it works great. The problem is there's nothing keeping it from happening again, the groove in the control bolt that the roll pin goes in is wide enough that it can just work its way down again. The more I thought about it, I realized I've had low oil flow ever since I bought this saw new in '03. Even now, it's just enough oil for my 16" B&C when turned all the way up.
Has anyone had this issue before? I'm wondering if this has happened over time, and would/could happen to the new pump if I replaced mine, or if my oil pump was just messed up from the factory, and that's what caused my low oil flow the whole time. Do any larger oil pumps (maybe from an MS360 or 361?) fit the MS260?
, so I guess I'll just stick with my fix and the new hard plastic output hose I put in, and hope it keeps working. If not, off to ebay for a used pump...
