I have a very used 391 (older finned cylinder) that needs a new piston and cylinder - I bought it as a parts saw basically knowing it would need some love to run again. What else would y'all recommend replacing at the same time that I do the tear-down to replace them? I am new to this world of chainsaw repair and could use some advice from the experts.
X4 on the seals Impulse line while your at it. Take pictures! Just did an 029 to 039 conversion. These are a Rubic's cube. But fun.
Hopefully the price on the piston and cylinder have come down. Stihl was mighty proud of them last time I checked. Definitely overhaul the fuel system while you have it apart.
The price for the OEM P&C is still quite high 300 + . there are some AM P&C kit starting to show up . They vary from 140- 190+ . I’ve got a fried 311 here that needs a new P&C . But all the AM kits have the three bolt intake block ,and this 311 has the 4 bolt intake . I’m tempted to find a used 3 bolt lock and try an AM kit .
Thanks y'all. I'm not new to wrenching - I spent ten years working on bikes and air cooled VWs so I'm not a total noob. From what I see the piston/cylinder for this is the 1140 020 1204. For the seals, there are two that seem to be indicated and I am not sure which is correct for this one: either 9639 003 1585 or 9638 003 1581. Anybody know the difference or how to tell which one is correct for this saw?
Y'know what? Go for it. Tear it down and see what it actually needs. You'll probably be able to ID or at least measure the seals. Let's see it on the healing bench!!!
I think you want 1585, the blue guys. I believe the others are for when you don't want to tear it down completely and replace with the crank still in place.
I think that’s a clam shell design. Once you peel the saw apart and lift the jug, crank pulls right out, as long as the clutch and flywheel are off, needed to change seals anyway.
Yup, clamshell. I thought if you don't do a full teardown, you can still replace seals with crank and cylinder in place. Thus, the other p/n. ? Never done out that way myself.
Not sure that you can. There’s a cast lip outboard of the seal on the flywheel side anyway. I’ve only done a few Stihl clam shells and on those it looks like that is the path. The seals don’t have the tin shroud to drive it into the annular space. They seem to rely on setting them in the lower half pocket and the compressing them when you set the jug.