MS660 Decompressor valve

[Forest2Furniture]

I've got a little (I hope) problem with my Stihl ms660

.

Did some milling yesterday, saw started great.

Finished the cut, stopped the saw, moved board.

 

Went to start saw again - no decompressor button!

Eventually found it on ground by tree trunk.

 

Has anyone got any ideas why it's come out, is it a common fault and more importantly will it cost me a fortune to repair?

[Mesterh]

You can buy a new one.

 

Dont think it will break the bank.

 

 

Look for FR Jones on the right hand side of the screen, they should be able to get you one.

[Forest2Furniture]

Thanks, but my only concern is will it have done any damage to the engine.

Although I suppose if it ran without a problem and I didn't notice until I came to start it again there shouldn't be any damege.

 

How easy are they to fit and do I need to take it to the dealer or is it a DIY job?

[raker]

Doddle of a job just screws straight back in there. Use a bit of locktight if you think it might come out again.

[Forest2Furniture]

Things not looking good!

Have taken old valve out and the bit that should be on the bottom appears to be rattling around cylinder!

[spudulike]

From what you have said, the end has fallen off the decompressor, if it had started leaking then the saw would have probably stalled rather than seized.

 

Just unscrew the thing and fit a new one. If you are worried about it coming loose then use a little studlock on it.

Spud

[spudulike]

Just read the last post - oh bugger:thumbdown:

Think I would pull the cylinder off and check out the damage to the piston crown, cylinder walls and cylinder top.

 

If you are lucky, all will be fine, if you are not then it could be ans expensive repair.

 

You could inspect through the spark plug hole and extract the thing through the hole or exhaust port but know what I would do if it was my saw.

 

Spud

[Forest2Furniture]

Forgive me for being dim but what about the bit that's rattling round the cylinder block.

If I put a new valve in and start it won't whatever is in the cylinder knacker it or am I as just said being dim?

 

Really appreciate the advice guys.

[Forest2Furniture]

Thing is, it started, I then cut a 9' plank of Yew without a problem.

It wasn't until I came to start it the next time that I noticed the button had fallen off, found it at the end of the log.

 

So, if there was any real damage it would have stopped the saw, yes?

 

Think I'm being to optimistic aren't I?

 

Bugger!

[Mesterh]

Could have been lucky and it only fell into the cylinder when the saw had stopped.

 

You have to get it out before you even think of pulling that starter cord.

 

 

Actually you want to make sure you dont rotate the engine even a tiny bit as it could get caught in a transfer port and damage the piston/rings etc.

 

Maybe whip the exhaust off, have a look inside and see if it will come out through the exhaust port(it should do).