Ms 170.

[jcquade]

I'm a bit perplexed although I don't know how these things exactly work. chainsaw has turned off. the chain was running like it was too tight but had plenty of play. looked at the clutch and it looks fine to me. the thing is it doesn't spin freely. you can feel compression when turning it like if I turn to fast enough it would start

 

[Stihl 99]

If the brake is not on, your chain should turn on the bar not free-spinning, but should turn with a little bit of effort.
This is how your sharpen the chain and I check tension as well by the feel of it. I take the scrench placing it behind the chain tooth push the chain forward to feel how tight or loose it is.

 

[jcquade]

If the brake is not on, your chain should turn on the bar not free-spinning, but should turn with a little bit of effort.
This is how your sharpen the chain and I check tension as well by the feel of it. I take the scrench placing it behind the chain tooth push the chain forward to feel how tight or loose it is.

yeah I understand that totally. the thing is it does take a little effort to turn it. but the Piston is going up and down when I'm turning the chain by hand. the break is not on. I've been sharping chains for last 15 years I never had this happen. I just don't know what would keep the crankshaft engaged while moving the chain. never thought about because I never had the issue.

 

[Stihl 99]

Oh wow, clutch is engaged then.

 

[Paul]

Broken clutch spring?
Or possibly the clutch came loose and is jammed in the sprocket

 

[STIHLTECH]

Remove the sprocket and clutch. Replace the missing or weak clutch springs. Make sure the needle bearing is OK and lube it. Check that the pump worm is spinning freely on the crankshaft and turning the oil pump. Look for any other loose or broken parts. Check sprocket for wear. Replace as needed Reassemble and check that sprocket and bar nose spins freely.