Stihl MS170 crankcase material

[dodge man]

I rebuilt a Stihl MS250 a couple years ago, it needed a new cylinder and piston. I was shocked at the number of aftermarket parts available off Amazon. It looked like you could build a saw from scratch. I spent around $100 and could have bought stuff for half that but I went for the high quality junk instead.

 

[nyone]

The ms170 is the cheapest saw they sell. I believe there about $200 new so I wouldnt go spending time much time/money fixing the crack until you figure out why it cracked.

Unless it was free or very very cheap I wouldnt even bother buying a used low grade saw like this.

 

[rangerfredbob]

Yeah, it's a pain to work on... but it runs great now!

Pretty sure it was just a weak spot, knowing the full history of the saw the coworker that had the saw originally (bought new) a tree fell on it not too long before it started idling high which broke the outer handle only (3 rubber isolators), was the first thing the new owner changed, then tried to tackle the high idle issue... started with an Amazon carburetor then an intake boot just for good measure... then of course the crank pan... Apparently the idle got progressively worse over time as the crack progressed I'm sure... probably started from the stress of the crushing spreading the crankcase a bit...

Put it together tonight since the part showed up today, started right up, adjusted the idle screw and it idles down real nice now

 

[209StihlTech]

Yup, magnesium. if the arc is a purplish/violet color is another indicator..........Mike

It's not magnesium it's aluminum. Stihl has never produced a magnesium clamshell style engine nor has any other company from my knowledge. On the left is a clamshell style engine with a plastic crankcase housing and engine made of aluminum, right is a pro style saw with a mag crankcase and aluminum cylinder. Stihl has used a mag piston in the past on the ms400 though.