Husqvarna 136 oil pump problem

[DavidMSmith]

My 10 year old Husqvarna 136 has had only occasional amateur use. The bar started to run dry – no oil issuing from oiler hole onto bar. Dismantled oil pump – stripped worm gear. Ordered a new one (non-OEM) from reputable eBay member. It came with new one piece rubber mounting block/pickup tube & filter – the old one was a 2 piece arrangement.

Fitted new pump – ran engine. Oil appeared at outlet from pump with engine running – great. Replaced metal plate covering rubber block over bar studs. Replaced clutch, bar etc. Left overnight – bar oil leaked out everywhere!

Read that leaks around the oil pump shaft are not unusual. Recommended to use a little liquid gasket to seal between oil pump shaft and rubber block. Did so sparingly – kept well away from oil pump intake and delivery holes. Left to dry overnight. Result – no leaks but now no oil being delivered up to bar oiling hole.

Got a replacement pump from the same supplier. Fitted new pump – with metal cover plate fitted oil leaks from bottom of rubber housing – nothing going up the channel to bar delivery hole. Put a little liquid gasket seal on again – stops leak at bottom but still no oil appearing where it should!

No sign of damage on replacement pump #1

What am I doing wrong?

I do have a concern re the size of the new rubber mounting block. When firmly located in the hard plastic crankcase housing, it stands ~ 2mm proud of the surface of the hard plastic. The moulded delivery channel stands another 1mm proud again. It’s as if the block is too deep – I would have expected the main body of the rubber housing and the hard plastic to be flush? Maybe when the metal cover plate and bar are installed, everything is being squashed down too much and closing over the intake and delivery holes? Unfortunately I binned the original 2 piece rubber block so can’t make a comparison!!

It’s not an issue of blocked hole in bar itself as (a) the bar oil hole isn't blocked and (b) there is no oil flow to the bar in the first place!

Any suggestions gratefully received!

[Ray1]

When placed side by side with the old one are there any differences in size? Are you 100% sure you are installing it correctly. No matter how reputable the seller on ebay the non original parts will still be cheap Chinese junk.

[peatff]

Different saw but probably similar set up. My 135 when the metal cover plate is installed the rubber protrudes through the slot in it to seal against the bar. I got it wrong once and the oil was running out at the bottom instead of going where it should.

[adw]

The 136 had leakage problems from between the pick up hose and the delivery hose, so this was replaced with a combined tube, the pump cylinder slides into the new hose, this normally made oil leakage much better, the assembly should stand proud so as when the outer plate is fitted and the bar tightened up a better seal is given, the filter was uaually a spring pushed onto the delivery pipe, if the oil is thich this can retrict oil flow, so pull the spring to open up the coils to allow better oil flow, the pump shaft not only rotates but has a throw, there should be an ecentric in the plastic pump gear which runs on a steel pin, turn the pump gear by hand and check there is a throw, the bigger the throw the higher the oil flow, never run the saw with out the bar and chain connected there is a high chance of the clutch cominh off on the over run, if no bar and chain are fitted remove the clutch and sprocket and check the oiling this way, the drive gear should be a tight fit on the crank, check its condition and that is is still tight.

[DavidMSmith]

The 136 had leakage problems from between the pick up hose and the delivery hose, so this was replaced with a combined tube, the pump cylinder slides into the new hose, this normally made oil leakage much better, the assembly should stand proud so as when the outer plate is fitted and the bar tightened up a better seal is given, the filter was uaually a spring pushed onto the delivery pipe, if the oil is thich this can retrict oil flow, so pull the spring to open up the coils to allow better oil flow, the pump shaft not only rotates but has a throw, there should be an ecentric in the plastic pump gear which runs on a steel pin, turn the pump gear by hand and check there is a throw, the bigger the throw the higher the oil flow, never run the saw with out the bar and chain connected there is a high chance of the clutch cominh off on the over run, if no bar and chain are fitted remove the clutch and sprocket and check the oiling this way, the drive gear should be a tight fit on the crank, check its condition and that is is still tight.

Many thanks for the input.

Will try stretching the spring.

Checked the pumps - the eccentric action is OK in both of them.

Thanks for safety warning about not running without bar - don't worry - I test it out without the clutch & sprocket fitted to avoid the overrun issue!

[DavidMSmith]

Different saw but probably similar set up. My 135 when the metal cover plate is installed the rubber protrudes through the slot in it to seal against the bar. I got it wrong once and the oil was running out at the bottom instead of going where it should.

Thanks for input - no slot in metal plate on my bar so I don't think there is opportunity for incorrect assembly.

[DavidMSmith]

When placed side by side with the old one are there any differences in size? Are you 100% sure you are installing it correctly. No matter how reputable the seller on ebay the non original parts will still be cheap Chinese junk.

Thanks for input. Think I've tried all assembly options - hence the posting on here! In your experience, are the OEM Husqvarna pumps better & hence worth a try? This & similar model Husqvarna saws seem to have a reputation for oiling problems even from new! (mine had to go back a few times under warranty)

[DaveyCrockett]

At the moment I have exactly this problem with a Husky 141, which has the same oil pump. Did you ever resolve this in the end? I am going back to first principles with this tonight and I'm determined to get to the bottom of it.

Edited May 23, 2016 by DaveyCrockett

[DaveyCrockett]

At the moment I have exactly this problem with a Husky 141, which has the same oil pump. Did you ever resolve this in the end? I am going back to first principles with this tonight and I'm determined to get to the bottom of it.

 

So far I have drained oil from tank and checked the position of the pick up pipe is sensible - it is. The breather tube has been knocked out cleaned and replaced. The pump assembly pumps oil when the pick up pipe is in a small tube of oil and the piston is rotated by hand in the same direction the worm drives it. The pump assembly, and one piece rubber tube/seal works although it is a cheap pattern part that cost £10.

 

I notice now that the worm on the crank looks damaged. It's like the worm has a double start helix. More worrying, there seems to be play in the big end bearings, which won't help positive engagement with the gear on the piston, not to mention the seals. I'll do a crankcase pressure test but it looks like this saw needs to come apart anyway.