046 has me stumped

[lambs]

My 25 year old Stihl 046 mag has started occasionally locking up when I try to start it. I usually get about 6" of cord pulled before it stops. But it will free up and then start normally and run great. I pulled the recoil starter and everything seems to be in great shape, although I am going to replace the starter pawls because they're cheap and if they are worn down enough to jam against the flywheel that could be the problem. I also pulled the compression release valve and spark plug. The valve needs replacing; it won't consistently catch. So I'm not sure what is going on, but I did spot an anomaly, pic attached below. You guys ever seen a hole like that? Thoughts? I think it may be time to break out the 461.

 

[albert]

Any rub marks on flywheel from coil contact?

 

[Wood Doctor]

I did spot an anomaly, pic attached below. You guys ever seen a hole like that? Thoughts?
-------------------------------
That almost looks like an impression left by a hard piston blocker that somebody used to prevent shaft rotation during a repair, such as a clutch or flywheel removal. Or a fioreign object got in their during a spark plug change.

 

[lambs]

Any rub marks on flywheel from coil contact?

I don't recall seeing any. I think I would have noticed discoloration from that.

 

[lambs]

I did spot an anomaly, pic attached below. You guys ever seen a hole like that? Thoughts?
-------------------------------
That almost looks like an impression left by a hard piston blocker that somebody used to prevent shaft rotation during a repair, such as a clutch or flywheel removal. Or a fioreign object got in their during a spark plug change.

Well, I'm the second owner so something could have happened like that before I bought it. I know it needs the compression release valve, so I'll put that in along with new pawls, and I'll look at that flywheel. The interesting thing is that the saw was still running. Would you run it till it dies? Since I have an almost new 461 standing by, the 046 might become a parts saw. I would not want it to break down in the field.

 

[Wood Doctor]

Well, I'm the second owner so something could have happened like that before I bought it. I know it needs the compression release valve, so I'll put that in along with new pawls, and I'll look at that flywheel. The interesting thing is that the saw was still running. Would you run it till it dies? Since I have an almost new 461 standing by, the 046 might become a parts saw. I would not want it to break down in the field.

I would say that it's time for a sale to someone who wants to rebuild it. Likely a new top end is required among other things. Chain saws do not last forever without restoration work.

 

[huskihl]

I believe that’s just a center locating hole for machining the piston. If it went all the way through, you’d have no compression, rather than excessive compression

 

[cscltd]

Is your starter pulley cracked on inside or warped with rope doubling up and binding?

 

[Ronie]

I believe that’s just a center locating hole for machining the piston. If it went all the way through, you’d have no compression, rather than excessive compression

That's what I was thinking.

 

[lambs]

I believe that’s just a center locating hole for machining the piston. If it went all the way through, you’d have no compression, rather than excessive compression

I hope that will be the case. The guy behind the counter pulled out a new piston and it didn't have a hole. But I bet you are correct. The hole is a little too perfect looking. Thanks for taking the time to point that out! Maybe pistons made in the 90's for that saw used a locating hole. Or perhaps the piston they showed me was for a different model altogether.

 

[lambs]

Is your starter pulley cracked on inside or warped with rope doubling up and binding?

Nope, but thanks for the suggestion.

 

[trains]

Ive come across difficult to pull start issues when the circular bit that houses the starter pawls, and the starter rope wraps around, gets too worn on the center of it.
Does it have lateral movement, or can you wobble it ? too much movement and it cants over and jams when trying to start.

Common wear item and pretty cheap and easy to replace, you have already done the starter pawls that sit in it anyway.

pics could help too.

 

[cookies]

pull the bar/chain off and see if that stops the resistance

 

[cscltd]

crank end bearing breaking up? usually they will bind and stop saw once been running though.

 

[FamilyTradition]

Interesting and valuable thread so please keep us posted. Good luck, Max.

 

[lambs]

Many thanks guys for the advice and your interest in helping me solve the problems.

Today I got most of the saw back together. New pawls and new compression release valve installed. I have pulled the starter cord at least 30 - 40 times and it has yet to lock up. The pawls don't look to be that much longer than the old ones, but I think at full extension the old ones must have been jamming against the inside of the flywheel.

I hooked up my compression gauge and am seeing 162 psi. That's the good news. The bad is that the comp release button is sticking in the release position. I squirted a little WD40 around the button stem and will try it again tomorrow. I guess if that fails I'll have to return the valve. Any suggestions on how to get the valve working consistently?

Thanks guys, as always.

 

[Maintenance supervisor]

Many thanks guys for the advice and your interest in helping me solve the problems.

Today I got most of the saw back together. New pawls and new compression release valve installed. I have pulled the starter cord at least 30 - 40 times and it has yet to lock up. The pawls don't look to be that much longer than the old ones, but I think at full extension the old ones must have been jamming against the inside of the flywheel.

I hooked up my compression gauge and am seeing 162 psi. That's the good news. The bad is that the comp release button is sticking in the release position. I squirted a little WD40 around the button stem and will try it again tomorrow. I guess if that fails I'll have to return the valve. Any suggestions on how to get the valve working consistently?

Thanks guys, as always.

Replace it with a husqvarna valve.

 

[HarleyT]

Looking in the plug hole, I see a whole lot of carbon. You might just be as well to pull the cylinder and have a look, and remove that carbon, and inspect things. Excess carbon can cause all kinds of trouble.

 

[lambs]

Looking in the plug hole, I see a whole lot of carbon. You might just be as well to pull the cylinder and have a look, and remove that carbon, and inspect things. Excess carbon can cause all kinds of trouble.

That carbon may be the only reason my compression is 162 lol .