Stihl MS362 killing oiler worm gears

[MervMaster]

Just rebuilt a 362 corpse the a i got for free from work. it had a bad connecting rod bearing, so its a total rebuild with a new crankshaft assembly.

After the rebuild it runs great, but wasn't getting any oil (this may have been a problem from before the rebuild), so i checked the oiler and the plastic worm gear had a bad spot where it got stripped. Pulled the oiler too to check, and it has a small rough spot in its rotation. Replaced both with OEM parts. new pump turns smooth, oil flows nice.

2 hours of cutting later, and i have no oil on the bar. the oil pump feels stiff, and the worm gear is again ruined.


any ideas? I'm getting a little frustrated with it, since the big scary rebuild went great, and I cant get the newb repair to stick.


Thanks in advance,

Merv.

 

[stihl86]

Are you sure oil is getting to the pump all the time? You'd have to check the tank vent.
Also, I've seen cheap bar oil take the paint off the inside of the tank.
But that would be very evident.
My logic is, if the pump runs dry and starts to drag, it will wipe out the worm fairly quick.

 

[farmguywithasaw]

What oil are you running and at what temp? Could be too thick? Could also be sucking in contamination from oil tank. Also did you pre lube the pump if it was dry right off the bat it could have damaged it?

 

[Ozhoo]

Did you replace the case bearings and if so are you sure that it's at the correct depth? Did you remember to put the circlip back on the crank between the seal and the worm gear? Also is the oil pump washer facing the correct direction? You can see where I'm going with this, anything that put stress on the worm gear will cause it to prematurely wear.

 

[albert]

Oem worm gear and pump?

 

[67L36Driver]

Did you remember to put the circlip back on the crank between the seal and the worm gear?

.

Exactly!

 

[MervMaster]

I did not lube the pump

the crank case bearings are the right depth with the clip installed

the parts are oem

It’s possible that I missed the little pinhole in the clutch drum where the worm gear arm is supposed to sit. I thought I had it right but now I’m doubting myself.

Thanks for getting back to me

What oil are you running and at what temp? Could be too thick? Could also be sucking in contamination from oil tank. Also did you pre lube the pump if it was dry right off the bat it could have damaged it?

Oem worm gear and pump?

Exactly!

 

[HarleyT]

Show us a pic of the ruined worm gear.

 

[stihl86]

That leg spring on the worm should drop into place on its own.

 

[MervMaster]

Dang. I’ll post a pic later.

 

[gmctyphoon]

Was The clutch side bearing installed in the case with the oil pump installed?

 

[Van462]

Once you put the new worm gear on and install the clutch but before the clutch drum in installed. Rotate the crank. If the worm gear is sitting correctly it shouldn't try to spin. If it does then the clutch is pulling the worm gear against the clip. With the clutch drum on and side cover/bar removed verify it doesn't oil at idle. Only once revved and the clutch is engaged.

 

[gmctyphoon]

Once you put the new worm gear on and install the clutch but before the clutch drum in installed. Rotate the crank. If the worm gear is sitting correctly it shouldn't try to spin. If it does then the clutch is pulling the worm gear against the clip. With the clutch drum on and side cover/bar removed verify it doesn't oil at idle. Only once revved and the clutch is engaged.

Without a bar and chain it will definitely oil at idle. Because the drum will spin without the resistance of the bar and chain.

 

[Van462]

Without a bar and chain it will definitely oil at idle. Because the drum will spin without the resistance of the bar and chain.

Good point forgot about that, could try putting slowly rotating crank with the brake on and off (plug out) to see if it feels different

 

[MervMaster]

Here’s the best pic I could get of the busted threads. I got a replacement worm in the mail today, I’ll report back on if it spins with the clutch or not.

 

[mountainlake]

Whats that plastic gear doing in a pro saw Steve

 

[2stroker]

Don't most all, Stihl, Husky, Jred, modern pro saws have one of the oiler gears made of plastic? Stihl 261-880 do. Husky 550-3120 do. Not sure about Echo or Makita.
2stroker

 

[pioneerguy600]

View attachment 810821Here’s the best pic I could get of the busted threads. I got a replacement worm in the mail today, I’ll report back on if it spins with the clutch or not.

I have seen many drives like that, up here in the winter the oil is too thick causing the pump gears to have a high resistance to rolling , the nylon cannot take the stress and strips the threads. See this on all makes of saws so not limited to just one design. The one thing that prevents this we have found is to run thinner winter grade bar oil. The only thing that I have found that causes the threads to strip is the resistance of the pump to turn over, possible also if there is something inside the pump causing high resistance.