Stihl 034: Piston almost froze up - why?

[davefr]

I stumbled onto a Stihl 034 that was priced right but went to give it a "test drive" and it would barely turn over. I could pull the cord but it was very hard to pull and there is no way I could pull it fast enought to start the saw. I'm just curious what the likely problem(s) are.

Do pistons warp in an overheated situation? Would a bent crank be likely? Could the lower bearings be bad?

Is it likely to be anything simple ?

 

[sedanman]

Is the chainbrake on? LOL. Other than internal engine damage the starter pulley could be cracked and dragging in the housing, or someone could have run it with the brake on, this melts the oil pump gears and the resulting molten plastic drags on the clutch. Fist thing to do is pull the muffler off though and look for piston scoring. If you can't take the muffler off at least take the top off and look at the cylinder fins if they're burned/discolored then the saw ran hot.

 

[HUSKYMAN]

Most likely the piston is scored. Probably on the piston and the cylinder wall. Stay away from this saw unless it is REAL cheap

 

[Fish]

Remove the plug, then try it. An excess buildup of carbon, or fuel
in the cumbustion chamber could cause a hard to pull condition.
If the piston scored or the rings stuck, it would pull easier.
fish
If it pulls hard with the plug out, it may be bearings or a coil
rubbing.

 

[davefr]

Thanks guys. I'm not touching this one. (too risky)

Is the 034 an orphan in the Stihl lineup? It's the first one I've come across and no-one seems to mention them much.

 

[stihltech]

034

One of the most underrated Stihl saws. I use onr for my BIG work.Quite light and powerful. Runs a 20 inch bar with ease. Weak point was the pulse hose. If it cracked and leaned out ( we always shut the saw down when it won't idle down DON"T WE?). the piston will lean seize, which is the most likely problem on the saw you looked at

 

[Methoss084]

If the cylinder checks out, make sure the coil isn't loose and dragging against the flywheel. Or like previously mentioned maybe a melted clutch bearing or oil pump drive gear.

 

[GTIspirit]

Weak point was the pulse hose. If it cracked and leaned out ( we always shut the saw down when it won't idle down DON"T WE?). the piston will lean seize, which is the most likely problem on the saw you looked at

Back from the dead! 'cause I have this same problem with an 034 Super..... It's like something is sticking or dragging when I pull the cord or turn over the flywheel.

What is this so-called "pulse hose?" I don't find it by that name in the service manual.

What I've eliminated so far as culprits is the pullcord and reel, because it's still hard to turn over with those removed and turning the flywheel by hand. I also removed the clutch drum thinking that might have been dragging or maybe the brake band was dragging, but still no difference. Next step will be to remove the clutch and flywheel to see if something is dragging underneath them. My other thought was the piston seizing, but I couldn't really tell by peering in through the spark plug hole, and no, that didn't make much difference, removing the plug and pulling the cord.

Thoughts? On the right track here?

 

[sefh3]

Back from the dead! 'cause I have this same problem with an 034 Super..... It's like something is sticking or dragging when I pull the cord or turn over the flywheel.

What is this so-called "pulse hose?" I don't find it by that name in the service manual.

What I've eliminated so far as culprits is the pullcord and reel, because it's still hard to turn over with those removed and turning the flywheel by hand. I also removed the clutch drum thinking that might have been dragging or maybe the brake band was dragging, but still no difference. Next step will be to remove the clutch and flywheel to see if something is dragging underneath them. My other thought was the piston seizing, but I couldn't really tell by peering in through the spark plug hole, and no, that didn't make much difference, removing the plug and pulling the cord.

Thoughts? On the right track here?

Check your PM's.

 

[andrethegiant70]

The 034 is an excellent saw. For some reason they don't get as much mention as the newer, sexier models. They are tough as nails, fairly light, strong runners, and dead relaible. Hard to pick a comparable Husky, maybe the 254, also a great saw. Forget the 55, the 034 is way better.

Having said that, there is nothing, buildwise, that is unconventional or problematic about this beast. Pretty standard stuff, they just got it all right on this model.

I'm guessing that either the piston is siezed or some water got in and froze the bearings (or both).

 

[GTIspirit]

After working on other stuff over the summer I finally had a chance to take a good look at my 034 Super. It's quite clear why the rope is hard to pull and the engine is hard to turn over. (Engines and mechanical things are my hobby, so I'm keen to see if I can fix it.)

Not sure how this happened to my father's saw while in my uncle's hands....

If I understand the repair manual correctly, there is no thrust bearing/shim on one side of the crankshaft, just two caged round ball bearings. So I don't really understand how this could happen. I guess the next step is to split the case and determine the real root cause. Best case I'm hoping I just need new bearings, worst case I need a new case. Piston and head are in decent shape, could use a little honing/polishing but look usable.

Thoughts on what could cause this and how common it is?

 

[luke_w]

i once had an 034 super given to me .....it would barely turn over.....tore it apart to see what was wrong .....after hours and hours of frustration ... i noticed that some body had adjusted ignition module so far over that it was rubbing on the fly wheel .....a 30 second fix that took me about 5 hours...good news is that it is now my favorite saw...i am amazed at how good it does ....i think it even has little more zip than my dads 036 pro.