021 smoked with chain brake.

Friend brought over an 021 he has had for 20 years. Said a worker smoked the saw when he slammed the throttle with the chain brake on for 1.5 minutes.

I was able to start it but then it felt off. So I shut it off and took off the bar and chain. Spur sprocket was stuck it felt like so I gave it a few taps with a brass hammer and got it off.

The needle bearing had complete melted and all the needles went klink klink klink.

There were chunks of mted plastic and when took the clutch off the entire area behind the clutch looked like it had been coated with melted plastic. It wasn't freshly melted from me starting it - this was old meltage.

I am going to take off the muffler and check the piston. Compression felt ok but he may have cooked the piston.

I cleaned the spark plug and some of the case. Needs a new sprocket and needle bearing and probably a new set of springs or just a new clutch.

There was a weird hard plastic film under that big washer below the clutch and above the worm gear. Anyone know what that is?

I can see a tiny bit of meltage on the top of the worm gear where the metal hook wraps around. The threads of the worm gear are fine and the until was pouring oil out constantly and the chain wouldn't stop moving because the spur sprocket was stuck onto the clutch from the melted plastic of the needle bearing and probably from needles that got wedges in there.

There was melted plastic on the worm gear hook that sits in the groove of the sour sprocket as well. Lot of melted plastic everywhere.

 

No crank wiggle either.

 

I think this can be brought back to life. Do you guys agree? BuckthornBonnie huskihl Thanks.

 

Maybe. The seal is probably toast, so it might require complete disassembly. Not sure it’s worthwhile on an 021

 

If not fixable, then a parts saw. Too bad.

 

But what is that huge plastic film there?? I looked up the seal and it doesn't have that plastic.

 

The plastic film in your last pic is the melted worm gear.

You’d have to remove the 4 pan bolts in the bottom of the saw to remove the motor to get to the seals

 

Hahaha hot damm I was trying to figure out what the hell that was!!! Wow that's hilarious. I guess you done see that before!!! Thanks!

Oh man that sounds painful to get to the seals. Well, I'll order the cheap parts first and see what happens. I'm thinking the piston must be a little scored too in which case the friend might not want this work done...>But I wouldn't mind doing it if he gives me the saw.

 

It’s a great learning experience once. Most of the stihl homeowner saws go together and come apart the same way as the 021

 

once you’re there, they’re the easiest to replace.

I have a couple 025s on the floor. If you figure out what you need and it works with one, PM me if interested

 

Thank you both.

 

Is there supposed to be a gasket for the muffler? There was none and I don't know if it was ever removed. Based on this diagram it would seem there is not one as the muffler on the saw resembles the one on the left in the diagram. Although the spark arrestor that was on the muffler resembles #13 from the muffler on the right in the diagram.

Or am I wrong and it does require the shield #2 and the gasket #3?

 

Thanks man. How is it possible that the shield and the gasket aren't there?? That's just crazy to me.

Yeah I just looked up the needle bearing, sprocket, and a 3-pack of the springs. I was able to stretch out the springs easily so I think they are toast.

Thanks for the reminder on the worm gear and the e-clip.

 

Possible if the housing damage is not to bad and the crankshaft is not damaged from the sprocket bearing failure the other problem would be getting the brake band to seat in the housing properly so it will not drag on the sprocket good luck Jb

 

Yeah there was definitely some melted plastic scattered here and there on the housing near the brake band. I will hit it with a wire wheel gently to remove any loose crud but I can't tell till I get the needle bearing or else it just won't sit right on the shaft.

Just ordered all the parts we discussed:

Needle bearing (oem)
3-pack clutch springs (oem)
Sprocket (oem)
E-clip for sprocket (oem)
Muffler shield (am)
Muffer gasket (am)
Worm gear (oem)

$72. Friend's brother who just paid for my dinner the other day. No labor charge from me.

 

Something I've never been concerned with because the only saw I have with a chain brake is the MS I have that gets used very infrequently. Neither my 090 0or my 028WB has a brake. The 028 has a moveable handle but that is it. None of my saws ever get that cruddy under the covers either. They get cleaned after every use and I usually pull the bars and take them apart and blow them out with compressed air. Don't use them much so I drain the gas out and run them dry before they get stored as well. When I purchased the 28 decades ago, I had the shop where I bought it port the jug and open up the muffler. It's loud and it screams. Every time they get a new (sharpened loop, the bars get flipped too and both bars have greaseable noses, something I don't like with the MS, you cannot grease the sprocket nose. Eventually, I'll replace the bar with a greaseable sprocket nose bar.

 

I have taken a carbide burr in the die grinder to machine the melted plastic on many saws with meltdown damage the stihl ms360 series that my fence contractor customer has a lot of issues with melt because they idle the saws with the brake on when they are doing fence boards and the sproket bearing fails JB