034 AV rebuild

[Eng208]

Hey guys. First post. I was given a locked up 034 AV about 10 years ago, maybe longer. I salvaged it by cleaning up the piston and cylinder with Emory cloth. I’ve been running it occasionally and cutting storm cleanups with some trees on the property since then. I have my first saw I ever bought in 95 which is an old Husky 36. That saw cuts way better than it should.
Anyway, I bought some new property and have been cleaning it up, dropping and sawing trees and the old Stihl started acting up. It would run good until it got hot, then I couldn’t keep it running. Would get hard to pull and start. Today I had enough of it. I threw it in the back of the truck and finally took the cylinder off. The top ring was locked to the piston and pretty scored. I ordered a big bore 036 kit and cylinder from HL Supply along with an oil pump and line. I found the oil line was split so my oil was going to the clutch. I also replaced the clutch. My pump was locked up too Seems several things all happened after I started using it heavy. I hope I’m making the right decision trying to rebuild this saw instead of spending money on a new 362. Any advice? I have a 251 I’m making do withfor right now but really need a saw on that 034 range.

 

[cuinrearview]

Why did the piston score? Unless you figure that out and correct it, you're wasting money on the new top end.

 

[Eng208]

Why did the piston score? Unless you figure that out and correct it, you're wasting money on the new top end.

It was straight gassed over ten years ago. I never replaced it. Just cleaned it up and ran it

 

[cuinrearview]

It was straight gassed over ten years ago. I never replaced it. Just cleaned it up and ran it

But you said it was scored again now after you cleaned it up. What made it happen this time?

 

[Eng208]

I figured it was just worn out.

 

[cuinrearview]

I figured it was just worn out.

They do wear out. Indeed. There are measurements to decide if the wear parts are shot or not, or if a mechanical failure happened. Going from running good to not over winter is usually something else.

 

[Bob Hedgecutter]

I figured it was just worn out.

In a way, you are correct- perhaps something is worn out- might be the fuel line, might be the crank seals, might be the intake boot, any or all might be worn to the point they have failed- cause an air leak and ruined the piston.
Or perhaps the bearings wore out, bits of them finding their way into the combustion chamber- scoring the piston and locking the ring into the groove, maybe the big end bearing, maybe the crank bearings, or maybe even the piston wrist pin bearing.
Maybe the measuring cup you use to mix fuel is worn out?

 

[cuinrearview]

In a way, you are correct- perhaps something is worn out- might be the fuel line, might be the crank seals, might be the intake boot, any or all might be worn to the point they have failed- cause an air leak and ruined the piston.
Or perhaps the bearings wore out, bits of them finding their way into the combustion chamber- scoring the piston and locking the ring into the groove, maybe the big end bearing, maybe the crank bearings, or maybe even the piston wrist pin bearing.
Maybe the measuring cup you use to mix fuel is worn out?

10 years from an 034 is pretty good. For your average homeowner or firewood hack it would be easy to justify a new unit. Always fun to unlock the mystery of why it went away though.

 

[Bob Hedgecutter]

10 years from an 034 is pretty good. For your average homeowner or firewood hack it would be easy to justify a new unit. Always fun to unlock the mystery of why it went away though.

Agree 100%, exactly why I am currently doing a bottom to top rebuild of an old 036.

 

[Eng208]

I don’t mean to be a smart butt but I was totally satisfied by a 034 given to me that I took apart and freed a stuck ring and cleaned up a scored piston, put it back together and ran the crap out of it for ten years cutting oak and pine before I had to work on it again. That was after who knows what kind of life before me. I’ve run two strokes for 40 years between motorcycles and small engines. I was in charge of maintenance for two different fire depts for 18 years and kept all the saws and fans running with a bunch of young guys operating them that had never operated a saw before coming to the fire dept.
I will check the crankcase seals as it did get hot. Maybe I can resurrect this for another 10 years. For me, that’s probably about all the firecutting years I’ve got left anyway. If not I guess I’ll be in the market for a mid size saw.

 

[rupedoggy]

You have to forgive us as we are kind of OCD about this saw stuff. I think you are using the best approach for your own particular situation. It always amazes me that some of us on the Site know our compression pressure on every saw, and every few months. How many know their pickup truck compression? Vehicle is maybe $32,000 and the saw $500! LOL

 

[Bob Hedgecutter]

You have to forgive us as we are kind of OCD about this saw stuff. I think you are using the best approach for your own particular situation. It always amazes me that some of us on the Site know our compression pressure on every saw, and every few months. How many know their pickup truck compression? Vehicle is maybe $32,000 and the saw $500! LOL

Dry:
1= 140psi
2= 135
3= 125
4= 135.
Did not bother testing wet- but you just happened to use the truck reference with perfect timing!

 

[rupedoggy]

Bob you are one in a thousand

 

[Bob Hedgecutter]

Bob you are one in a thousand

Been called worse!

 

[Eng208]

I check my boat compression before and after boating season. Don’t really check my saw compression. If it changes the way it pulls, I know something is up but truthfully, this is the only saw I’ve ever had need a rebuild.

 

[Totembear]

Just rebuild it and have fun doing it. The 034 is a good saw. I've got an 034S and I love it. While your at it replace the seals. 1 thing down that can go wrong.

 

[Eng208]

But you said it was scored again now after you cleaned it up. What made it happen this time?

Well, I went back and checked everything that could have caused it to be a problem again. Crankshaft bearings. I checked for play and my crank moves a considerable amount on both sides. So the piston was probably rocking pretty good in the cylinder.

 

[cuinrearview]

Well, I went back and checked everything that could have caused it to be a problem again. Crankshaft bearings. I checked for play and my crank moves a considerable amount on both sides. So the piston was probably rocking pretty good in the cylinder.

If the bearings are shot, the seals most likely are too. That's where your air leak came from. Time for a complete overhaul.

 

[scallywag]

I checked for play and my crank moves a considerable amount on both sides.

The crank has movement or the rod?....Sideways movement of the rod big end is normal.

 

[cuinrearview]

The crank has movement or the rod?....Sideways movement of the rod big end is normal.

That's not the way I took "on both sides"