Stihl chainsaw almost locked up-?

jmc · Oct 5, 2009

Hello,

I can barely pull the starter cord on my small Stihl (model 009). It will turn over once with a hard enough pull. Air filter is clean and it turns freely with the spark plug removed. Worked ok the last time out- maybe 3 yrs ago. I was hoping to use it in the morning. Any suggestions?

Thanks,

JOhn

RalphVa · Oct 5, 2009

Did you try it after you put the plug back in?

What'll lock them up is fuel sucked in and attempt made to compress it.

Be sure you're trying to start it with the throttle locked on. If the lock doesn't work, tie a cord to lock it full open. Two cycle engines have got to have the throttle full on to start properly.

The routine usually is lock on throttle. Pull 2 to 4 times with full choke until it fires. Then about 1/2 choke, pull, and it starts. Use the same routine with my 2 cycle grass whip.

My 009L still works after more than 35 years. Think I bought it in 1972.

Sometimes, a shot of starting fluid into the air cleaner hole is needed but usually only on very cold days.

Ralph

jmc · Oct 5, 2009

Hi Ralph,

I put the plug back in and it still pulls hard and just makes it thru the compression cycle once. And that's with the throttle locked open. I'm pretty sure it has something to do with the cylinder being completely sealed during one phase of the stroke.

Thanks,

John

jiNpa · Oct 6, 2009

jmc said:
Hi Ralph,

I put the plug back in and it still pulls hard and just makes it thru the compression cycle once. And that's with the throttle locked open. I'm pretty sure it has something to do with the cylinder being completely sealed during one phase of the stroke.

Thanks,

John

Is it a new plug? Its not too long is it? Just a wild guess.

jiNpa · Oct 6, 2009

jmc said:
Hi Ralph,

I put the plug back in and it still pulls hard and just makes it thru the compression cycle once. And that's with the throttle locked open. I'm pretty sure it has something to do with the cylinder being completely sealed during one phase of the stroke.

Thanks,

John

Sounds like the piston is hitting the spark plug. Did you recently replace the plug? If so make sure its not too long.

20 20 · Oct 6, 2009

If it pulled over easy with out the plug then jammed again with it I'd take a hard look at the plug. I'd also stay away from starting fluid, not really a good solution to any engine.

Treemonkey1000 · Oct 6, 2009

Make sure it isn't your rope pull binding. If the case is cracked or the pulley is binding that will make it hard to pull. Been there done that. That is a pretty small motor so it shouldn't take much to spin it under normal conditions. With the plug out and it still binds then I would look at the rope pull portion. The pulley holding the rope can get dirt and grit under it and bind up pretty good. Just be careful if you get into that as the recoil spring can get you. Plus putting that recoil spring in is more fun than a Proctologist visit.

Gator6x4 · Oct 6, 2009

jmc said:
Hello,

I can barely pull the starter cord on my small Stihl (model 009). It will turn over once with a hard enough pull. Air filter is clean and it turns freely with the spark plug removed. Worked ok the last time out- maybe 3 yrs ago. I was hoping to use it in the morning. Any suggestions?

Thanks,

JOhn

Remove the muffler and clean the exhaust port. It sounds like carbon is blocking the exhaust port and not allowing the engine to breathe. When the spark plug is out, the engine will spin freely because it can breathe. Use a sharp pointed wooden stck to clean the ports, do not use a screw driver. Also when cleaning the ports, pull the start rope and move the piston away from the port. The muffler can also be stopped up causing the engine to be unable to exhaust air. So, if the exhaust port was clean when you removed the muffler check the muffler for an obstruction.

jmc · Oct 6, 2009

OP here. Thanks for the responses. It's definitely not the plug or pull cord. You can here air/gas escaping very slowly on the compression stroke. I had started to remove the muffler but it's got a metric torx screw deep in a counterbore, probably tighter than the dickens. I'll do that as a last resort since it seems like a plugged exhaust would have been noticable the last time I used it.

In the meantime, as I look down thru the carb throat it seems like I should be able to see into the cylinder at some point in the cycle. I can't but there is something relective down there that deflects a little at one point in the cycle. This motor may have a reed valve stuck in there someplace, which would be consistant with not using it for several years and not draining it of gas before that. Any comments on that?

Also, my can of carb cleaner does not recommend squirting it into the carb if the engine is not running. How do I clean this up if there's varnish in there?

Thanks,

John