Stihl 041piston lockup at start

[Cedar Row]

I have a 1977 vintage Stihl 041 that runs great, it is still my go-to saw, but it has recently had an intermittent piston lock-up on restart. I usually can pull gently on the start cord and it will loosen and eventually will start.
Yesterday it did that and the first time the gentle pull released the piston and the saw started. Next restart the saw locked up, I loosened it again, it locked up next pull. It will lock up with the spark plug out. Once I am able to start it, it runs fine again. Any suggestions?

 

[Old2stroke]

Best guess would be something going on with the recoil starter, rope doubling over and binding, worn parts that engage the FW, pawls on the FW. When it locks up, remove the starter and turn it over with the FW and see if it is still locked up.

 

[Cedar Row]

Best guess would be something going on with the recoil starter, rope doubling over and binding, worn parts that engage the FW, pawls on the FW. When it locks up, remove the starter and turn it over with the FW and see if it is still locked up.

Thanks, I hadn't checked that.

 

[SteveSr]

I have a 1977 vintage Stihl 041 that runs great, it is still my go-to saw, but it has recently had an intermittent piston lock-up on restart. I usually can pull gently on the start cord and it will loosen and eventually will start.
Yesterday it did that and the first time the gentle pull released the piston and the saw started. Next restart the saw locked up, I loosened it again, it locked up next pull. It will lock up with the spark plug out. Once I am able to start it, it runs fine again. Any suggestions?

Could also be failed crank bearings. Someone else may be able to answer whether or not these used plastic bearing cages or not. I wouldn't run it until you got this figured out.

 

[Cedar Row]

Disassembled the saw, carbon on the top of the piston, light scoring on piston sides and cylinder. Probably is the problem. Not sure what to do next. I will definitely have a clean saw. Source for piston and cylinder for 041? Maybe get by with light scoring?

 

[SteveSr]

Disassembled the saw, carbon on the top of the piston, light scoring on piston sides and cylinder. Probably is the problem. Not sure what to do next. I will definitely have a clean saw. Source for piston and cylinder for 041? Maybe get by with light scoring?

Post some photos of the P&C. What do the crank bearings look like?

 

[Cedar Row]

Post some photos of the P&C. What do the crank bearings look like?

Will do. Bearings look OK. Saw was really cutting good, but hard start was a problem. Once I got it started it ran fine. I was going to replace the piston several years ago, but the aftermarket piston didn't look as good as the old one, so I just replaced the rings. The present piston is the original. I use the saw in firewood season, only occasionally the rest of the year.

 

[Old2stroke]

Light scoring will NOT cause an engine to lock up. Bad bearings are a possibility although it's had to imagine the saw would run fine if they are bad enough to lock up the saw. When it locks up, you have to remove the recoil starter and turn the engine over with the flywheel to see if it still locked with the starter off and if you can feel any roughness in the bearings as you rotate the engine by hand.

 

[SteveSr]

Will do. Bearings look OK. Saw was really cutting good, but hard start was a problem. Once I got it started it ran fine. I was going to replace the piston several years ago, but the aftermarket piston didn't look as good as the old one, so I just replaced the rings. The present piston is the original. I use the saw in firewood season, only occasionally the rest of the year.

Wear on the intake side of the piston ( photo 1) is caused by lack of air filtration. Time for a better or new OEM filter.

 

[Cedar Row]

Wear on the intake side of the piston ( photo 1) is caused by lack of air filtration. Time for a better or new OEM filter.

 

[Cedar Row]

Thanks! Good filters for this saw have been hard to find, last one I bought wouldn't fit. I'll see what I can find.

 

[Cedar Row]

Anyone find a good source for 041 filters that fit and are effective? I have an old one that has been cleaned many times, probably has lost some of it's filtering capacity. It does fit the saw though.

 

[Woodslasher]

Anyone find a good source for 041 filters that fit and are effective? I have an old one that has been cleaned many times, probably has lost some of it's filtering capacity. It does fit the saw though.

I’d check with your local Stihl dealer, or just buy an oem one.

 

[SteveSr]

Anyone find a good source for 041 filters that fit and are effective? I have an old one that has been cleaned many times, probably has lost some of it's filtering capacity. It does fit the saw though.

Got the Stihl part number(s)?

You can look online for NOS. They may still be available from Stihl BUT you may have to order each half separately to make a complete filter.

 

[Cedar Row]

Got the Stihl part number(s)?

You can look online for NOS. They may still be available from Stihl BUT you may have to order each half separately to make a complete filter.

 

[Cedar Row]

Got the Stihl part number(s)?

You can look online for NOS. They may still be available from Stihl BUT you may have to order each half separately to make a complete filter.

Thanks, I actually found a site that not only matched the part number, but gave the actual measurements of the pins. Should be here soon!

 

[SteveSr]

....but gave the actual measurements of the pins.

Sounds like typical Chinesium AM. May or may not fit or filter properly. Such AM filters are generally held in low regard here... Why not get an OEM?

 

[stihltech]

Was there any smoking when it started? Quite common for bar oil to leak past the o ring and lock the piston.

 

[Cedar Row]

Started ok, ran fine, no smoke when cold , shut down, restart attempt saw was locked. When I disassembled the saw,. I noticed a split in the cylinder gasket. Otherwise things looked normal, except the carbon on the piston.

 

[Cedar Row]

Sounds like typical Chinesium AM. May or may not fit or filter properly. Such AM filters are generally held in low regard here... Why not get an OEM?

You were right. Hard to find oem filters.