help with bar oil pump

[pleasant]

This could simply be wear in the pumping mechanism...is it the original pump? If so, then it's getting on. The reason it's not pumping is because the internal pump 'gearing' teeth are worn I should imagine. See it a lot on these 460's. You can blow air through so no blockage, but still not pumping, because it isn't actually a blockage, but the gap between the mating surfaces of the pump have worn down to a point that they aren't actually doing anything. New, genuine Stihl pumps come out at around £75 plus vat.

[spudulike]

Bearing in mind that you know there is no blockage and the pinion and arm are OK, I would say that Pleasant is correct.

I used to test by attaching a bit of tube to the oil pickup or oil outlet union and blowing down it whilst turning the pump gear slowly. If the air flows through with little resistance, the pump is worn and you can also do similar with WD40. Basically, the end of the pump shaft has a flat on it and when it spins, the pump produces enough vacuum to pull the oil out of the tank. If the alloy body or shaft wear too much, the pump will stop working.

I found this on a few old MS200Ts but less so on larger saws as they are used less but it is now the most likely cause if the pickup is clear of debris and the tank has been flushed out.

£75..ouch, the price of spares is getting stupidly expensive.

[Muddy42]

1 hour ago, pleasant said:

This could simply be wear in the pumping mechanism...is it the original pump? If so, then it's getting on. The reason it's not pumping is because the internal pump 'gearing' teeth are worn I should imagine. See it a lot on these 460's. You can blow air through so no blockage, but still not pumping, because it isn't actually a blockage, but the gap between the mating surfaces of the pump have worn down to a point that they aren't actually doing anything. New, genuine Stihl pumps come out at around £75 plus vat.

 

I have not owned this saw from new, so I cant tell if its original, but it could be.  I think a new pump (and worm gear for good measure and they are cheap) has to be the next step.  The lines either side of the pump are functioning fine.  I have pushed a lot of air/white spirit either way through the pump so don't think there is a blockage, it must have failed or worn somehow.  The loss of the oil adjustment functionality is reason enough for replacement anyway.

 

Thanks

 

[spudulike]

Just read your last post again.....have you not managed to get fluid or air through the pump? Any blockage will be on the pickup side of the pump so any fluid/pressure needs to go on the pump where it pumps oil from. As I said earlier, try rotating the pump gear whilst putting WD40 through it as in one position, the shaft flat will be in a position that will allow both holes to be pretty much open and the fluid should flow through easier.

[Muddy42]

6 minutes ago, spudulike said:

Just read your last post again.....have you not managed to get fluid or air through the pump? Any blockage will be on the pickup side of the pump so any fluid/pressure needs to go on the pump where it pumps oil from. As I said earlier, try rotating the pump gear whilst putting WD40 through it as in one position, the shaft flat will be in a position that will allow both holes to be pretty much open and the fluid should flow through easier.

 

Yes I have tried forcing air/wd40/solvent through every which way whilst rotating the pump gear (or wiggling it with needle nose pliers).  Yes I can get a little bit of fluid to move through it, but its not great.  I don't have the right punch to dismantle the spindle so I've called it quits and ordered the replacements.  As described, the adjustment function is broken and the pump gear feels crunchy, something is just not right with the existing pump. 

[spudulike]

OK, probably the simplest solution for you.

I use a small panel pin ground flat to pop that small roll pin out and then you can withdraw the adjuster and the gear once the small plastic plug is removed.

The pump is probably blocked but not sure what that crunching is but guess all will be good once the new one is fitted.

At least you have learnt a bit.

[Muddy42]

12 hours ago, spudulike said:

OK, probably the simplest solution for you.

I use a small panel pin ground flat to pop that small roll pin out and then you can withdraw the adjuster and the gear once the small plastic plug is removed.

The pump is probably blocked but not sure what that crunching is but guess all will be good once the new one is fitted.

At least you have learnt a bit.

This is making me feel guilty now! I'll try the panel-pin-punch out of curiosity, given I know I have a new pump on the way.  I can compare the functionality of old and new by blowing through them.  It might be worth the new pump for the oil adjustment alone.

 

[Muddy42]

Right, so I got the spindle out using @spudulike's panel pin technique, cleaned everything up (cotton buds, solvent, syringe) and blown through and reassembled. But its still not pumping oil.  It shows a fair bit of resistance when reassembled and blown through with my mouth (whilst rotating the gear). I'll wait for the new pump mechanism to arrive and compare to that. Some part or the gear teeth must be worn.

[spudulike]

I once had a plastic pinion that looked perfect but when you followed the thread whilst slowly turning the pinion, the thread neatly went from a helix in to a perfect ring where the pump had got tight so the gear of the pump was never going to turn.

Is the arm on the pinion relatively tight? If it is too loose, it won't work.

[adw]

Back to basics, has the pump shaft got a throw? ( reciprocate ) when you rotate the shaft it should move in and out to create a throw, no throw no oil!