Husky 3120xp Rebuild

Oh boy here we go. So after passing on the MS460 my buddy wants me to take a look at his Husqvarna 3120XP.

Right off the bat it's got a missing chain brake handle and literally had about 10lbs of sawdust/bar oil all over the place.

I took off the muffler and the piston was scored. Fast forward when I removed the piston the rings were melted onto the piston so that needs to be replaced.

There was so much dirtiness I couldn't bear to work on it like that so I cleaned it up.

Here are the before pics:





















Pretty sure this anti-vibe needs to be replaced. I think the rubber part is vulcanized to the metal part and they were completely separated. Need to look up the parts diagram to confirm.



There was a lot of crud near the ignition module holy moly.











Someone please tell me why it needed a 3/16" wrench for the cylinder bolts. I guessed it was 4.5mm and of course my wrench set only has 4mm and 5mm.

The bottom of this cover was caked with stuff and so was the carb.











Intake side of the piston.



Scored exhaust side. Rings were melted.

 

And here's after I cleaned it up. Took a while. Like 5 hours. Scraping with a brush, a screwdriver, a cloth, brake clean at the carb area, and otherwise I carefully cleaned it up with the parts washer. That parts washer is pretty darn handy dandy if I do say so myself!

















The cylinder doesn't look so bad. I think it should clean up nicely.

 

So as far as parts go I need the following:

Piston kit
Cylinder gasket
Air filter
Spark plug
Chain brake handle
Flywheel side anti-vibe mount
Carb gasket kit
Fuel filter

It came with a 48" bar lmfao. How the hell am I supposed to mount that bar on the power head???? Hahahahaha. That's just ludicrous.

Also there's something funny with the manual oiler. I pressed the lever and now the lever won't retract so I don't know what's going on there. I still haven't taken the covers off on the clutch side to get to the chain brake mechanism but that I shall save for tomorrow's adventure. *Edit* there is no cover to get to the chain brake mech because it's part of the cover! Doh!

 

Looks like the anti-vibe has a post that screws into the tank body that has a flat metal part to it that the rubber part attaches to. Left side of the pic so I'll have to use a flat head and twist that metal plate off.

Part #501814702.

 

Can I call the manager on this guy for saw abuse?

 

I try to throw in the mandatory "Dude you should really try and take the cover off the saw and give it a brush every once in a while....even if you have to bring it to me it's going to be worth it in the long run" every few conversations....but it's hard to teach an old dog new tricks.

 

The chain brake issue is more severe. I didn't wash this part yet but I went out to take a peek and the brake band is broken, the guides are pretty worn, the chip guard is missing, and it seems like it might just be worth it to buy the entire assembly for $150 rather than mess around with all the individual parts. You get a new tensioner, new guides, new chip guard, new brake band, new brake handle.......all in one shot.

 

You don’t see many burned up 3120’s because the carb has a fixed H jet and they’re set pretty rich. And limited ignition. Be careful cleaning up the cylinder as they’re about $500.
Replace the fuel line and filter, carb kit, seals, and do a vacuum/pressure test when you’re done

 

It looks like the break handle got melted off.

 

Sounds like a plan.

Yeah and look at the brake band. I've never seen a brake band disintegrated like that. There was a lot of friction there and also if you look the inside of the clutch looks a little discolored, a little blued. I'm guessing there was so much crud in there it created a lot of heat. I don't know how that chain brake melted off like that. That's not a clean break from what I can tell.

 

Updated parts list.

Piston kit
Cylinder gasket
Air filter
Spark plug
Chain brake handle (complete kit)
Flywheel side anti-vibe mount
Carb gasket kit
Fuel filter
*********
Clutch needle bearing - old one was shot. Cleaned it, lubed it, put it on the crank, and it was all crunchy and nasty. Not smooth at all.
Fuel line
.404" 7-tooth sprocket

All oem minus the NGK spark plug

 

crank seals?

 

I didn't take the flywheel off yet. Nor the oil pump. So I'm going to do that tomorrow and see what the heck is what. I'm watching a video of a 3120 case split rebuild and it looks like the clutch side seal is part of the oil pump housing as opposed to being tapped in directly onto the bearing. Flywheel side looks "regular". Given the heat issues it might need that thin o-ring as well so I'll order that if I need to as well.

 

make sure you clean the mating surfaces and torque the flywheel to spec

 

I ain't going to put it on until AFTER I put the piston in!

 

Got the new cover in the mail. Decided to clean up the old one. After cleaning it up I noticed that the chip guard is riveted on. What the?

The new one is too.

Are these not replaceable/serviceable?

Got the new chain guides that attach to the saw body as well. Old cover cleaned up nicely.

 

Pop rivets are easily replaceable. Drill or chisel the head off and it should come right out.

 

Yeah I have a rivet tool but why didn't they just use a screw?

Every other chip guard I've ever seen either has posts where it friction fits or a screw to hold it in.

 

So went to take off the oil pump and noticed that someone had sealed the oil pump with silicone. I don't think that's the way it's supposed to be but what do I know.

Under the oil pump I saw a lot of grey looking grease on the bearings - you can see this in the pics - as well as quite a bit of sawdust.

Seems to be that the oil pickup line was leaking so that needs to be replaced.

Then I decided to take the handle off and clean the hidden parts of the saw and man it was disgusting. I mean a pound of crap in there.

Tacked the flywheel and promptly bent my flywheel removal tool. I had to resort to giving it about 8 tappy-taps with the brass hammer and the flywheel nut flush with the crankshaft. Luckily it broke free.

Fixed the flywheel removal tool with the bench vise. Man am I glad I got that vise and restored it. Came in super handy dandy yet again.

Now the question is whether or not I should replace the bearings. They seem to roll pretty smooth to me but similar to the MS460 this saw was beaten to death and there were lots of indications of it running hot and generating a lot of heat on the clutch side. Given the debris under the oil pump I think it may be a wise decision to do the saw justice and replace the bearings.

huskihl BuckthornBonnie M2theB you agree with my plan o' action?

I made a short video of me spinning the crank by pushing the connecting rod up and down. I did not lubricate but had cleaned it as best as I could with the parts washer.









What the heck is this foam piece and is that supposed to be there? There was a bit of plastic separated from the foam as well. Wth?





Grey bearing grease. After cleaning I could see shiny steel.



The plastic from the foam piece.



Manual oil pump area for my records when I put it back together.











Yuck.



Double yuck.





Bent tool.





All straightened out.









Bit of corrosion on the flywheel side of the crankshaft.