Stihl MS 170, acting really funny

[Leimkuhler]

My ms170 is about two years old, and used pretty much everyday ( 3 to 5 hours daily depending on tree and weather ). It's been a damn good saw up until recently. The saw will run when under load but soon as you left off the throttle it dies, just before this happened it would take twice as many pulls to get it to start as usual normally 2 pulls and she fires , not any more now...
I checked the L screw and the manual says that factory setting is two turns out. I have made minor adjustment back and forth and that doesn't help. I took muffler and card off to check piston, and there are no scores, nothing unusual. When I took carb off it was pretty dirty with oily saw dust , some inside where the butterfly's are. I tore into the carb deeper and black stuff came out with the fuel, and found dirt on top of the metering diaphragm ( black stuff on towel is what came out of carb).

I also have a carb that is just like it with different model numbers on it ... Im thinking that the carb needs rebuilt ? I don't know though.


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[Leimkuhler]

Another thing that I found unusual is that when I pull the cord to start the saw, the chain turns as I pull the cord. I have never seen this before. Is that normal ?


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[AKDoug]

That's a lot of use for a saw designed for occasional use. Clean that carb up first. Then, clean your clutch up. I'd bet you also need new clutch springs. Once that's done, see how it works.

 

[Leimkuhler]

That's a lot of use for a saw designed for occasional use. Clean that carb up first. Then, clean your clutch up. I'd bet you also need new clutch springs. Once that's done, see how it works.

Ya, I know it's probably went threw it's life cycle twice.

I put it back together she fires right up but dies after I lift off the throttle.....


I know it's only a 175 dollar saw new, I could just go get another but I am uneducated on the saws specs. I take the 170 up in the tree with me when it's needed. But am having to hassle with it more than I want up there. Is there any recommend pro series saws similar to the ms170 ?


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[AKDoug]

Did you look at the piston from the intake side? With that much junk in the carb over time, it wouldn't surprise me to see it showing a bunch of wear?? The carb, with a little work, can be replaced with a WT215 Walbro (do a search on this site for the info). The WT215 should cost less than $30 at a Stihl dealer. I've had terrible luck rebuilding the stock carbs on those saws.

 

[Leimkuhler]

Did you look at the piston from the intake side? With that much junk in the carb over time, it wouldn't surprise me to see it showing a bunch of wear?? The carb, with a little work, can be replaced with a WT215 Walbro (do a search on this site for the info). The WT215 should cost less than $30 at a Stihl dealer. I've had terrible luck rebuilding the stock carbs on those saws.

Ya, I looked at both sides of piston, looks shiny with no score or anything. Looks pretty much new.


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[old-cat]

Shiny ain't new looking. That's wear.

 

[Leimkuhler]

Oh, well guess that explains a lot. That saw has seen a lot of hours. Wouldn't doubt it if she's worn out.


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[old-cat]

Just put a new piston kit in and new fuel line, impulse, etc.

 

[farrell]

Sounds like it may have an air leak

 

[Leimkuhler]

Ya, I need to do a compression test on it, think I'm just gonna drop it off at the dealer. Got a lifetime warranty on it. Was just hoping something simple.


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[old-cat]

Ya, I need to do a compression test on it, think I'm just gonna drop it off at the dealer. Got a lifetime warranty on it. Was just hoping something simple.


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If he's a "good guy" take it to your dealer, otherwise the price might not be worth it.

 

[showrguy]

Ya, I need to do a compression test on it, think I'm just gonna drop it off at the dealer. Got a lifetime warranty on it. Was just hoping something simple.


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you got a "lifetime" warranty on a ms170 ????
i gotta hear more about this...

 

[Leimkuhler]

That's what they told me at the dealer when I bought it


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[Leimkuhler]

I'm sure when I tell then what I use it for they say , that voids the warranty, hell I don't know it's worth a try,


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[KG441c]

Just rebuilt a ms 180 acting the same way. Worn oil seals that was caused by motor mount screws underneath saw vibrating loose and also bad about vibrating the crank cover bolts loose also on thoso models

 

[jackjcc]

If there is black stuff in the carb it could be from the fuel line breaking down. That much daily use is equal to a decade of what those saws are designed for.

 

[Leimkuhler]

If there is black stuff in the carb it could be from the fuel line breaking down. That much daily use is equal to a decade of what those saws are designed for.

Ya I know, if I need to retire it , it will be fine with me , she made a lot of money for us.


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[jackjcc]

Ya I know, if I need to retire it , it will be fine with me , she made a lot of money for us.


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You don't need to, but it if you want to you can send it to me?

 

[Leimkuhler]

You don't need to, but it if you want to you can send it to me?

Well let me rebuild it for you first


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