Are they running smooth and quietly and is there any up and down play? Does that saw have a recessed seal on the flywheel side?
MS461 Piston failure diagnosis
- Thread starter JonCraig
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A thorough inspection with a really good flaslight of the bearing cages is a must, but I wouldn't split the cases unless I see a problem. I can't tell from the pic if the saw is a high hour saw, or the previous owner just was a slob.
Most debris chunks don't get on the seal side of the bearings That I've ever seen.
Flush it out with WD-40 a couple times and blow the crankcase out with compressed air. If you tilt the saw on it's sides, it will let the gook flow out from behind the bearings that has pooled up.
The bearings felt really good when I've tried turning it over, but at the moment the top end is still on, so it's hard to tell for sure. But it definitely feels "normal", just with low compression. Like, you can't tell a difference between with the decomp on vs off. I'll know a lot more once I get it broken down (and will take pics!). Will be sure to clean it first to avoid more contamination. If there's pulverized piston powder in there, I'll split the case and replace.
Air filter looked clean, but it's a mesh looking thing, not like the paper filter with felt pre-filter on my 460. Cheap aftermarket filter maybe?
Air filter looked clean, but it's a mesh looking thing, not like the paper filter with felt pre-filter on my 460. Cheap aftermarket filter maybe?
You know how to split that case?
Nope. But I'm willing to read a service manual & buy a case splitting tool. That, and I have more time than sense. 
No need to buy a spliter, make one out of angle iron. Lots of posts on how to.Nope. But I'm willing to read a service manual & buy a case splitting tool. That, and I have more time than sense.
That, too. Since I DEFINITELY have more time than money.
Funny story. I should have realized that (I think?) Stihl got rid of the "Magnum" designation for the 461. Thus, the sticker on this one should have been dead giveaway. And in the right light, the tag on top says 460. Aaaanddd, the starter has the spot for the rectangular badge, not the round one like the 461. You more experienced guys would have spotted that straight away. But I'm still happy with an(other) MS460 for $100. Like I said, the 25" Rollmatic ES & like new chain are worth that.
The bearings feel great--I have no worries there. The inside of the crankcase (that I could see) had no foreign debris. I'll of course still be flushing it for good measure.
The cylinder looks (in my opinion) like it'll do just fine. But you guys correct me if I'm wrong. I can only barely feel ridges in the cyl wall, and nothing hangs a fingernail. I'm thinking of just trying the scotch brite ball thing I've read about here. This will be my first attempt at a cylinder cleanup.
Anyway, you asked for pics, so here they are. Whatcha think?
The bearings feel great--I have no worries there. The inside of the crankcase (that I could see) had no foreign debris. I'll of course still be flushing it for good measure.
The cylinder looks (in my opinion) like it'll do just fine. But you guys correct me if I'm wrong. I can only barely feel ridges in the cyl wall, and nothing hangs a fingernail. I'm thinking of just trying the scotch brite ball thing I've read about here. This will be my first attempt at a cylinder cleanup.
Anyway, you asked for pics, so here they are. Whatcha think?
Here are cylinder pics:
Lean seize prob sucked air and leaned out.
So I'm making a shopping list:
Impulse line
Fuel line
Fuel filter
carb kit
intake boot
flywheel side seal
clutch side seal
piston
rings
base gasket (tbd)
Anything else I"m forgetting?
Impulse line
Fuel line
Fuel filter
carb kit
intake boot
flywheel side seal
clutch side seal
piston
rings
base gasket (tbd)
Anything else I"m forgetting?
Cyl base gasket unless you are deleting it.
And Stihl OEM seal drivers sure would be nice .
What's a "seal driver"?
edit: this thing?
edit: this thing?
Is the ign side seal recessed?
Here it is:
Looks flush with the cases right?
Now you have to get the seals out without scratching the cases or crank.
Flush with the inner-part of the case, yes. Different parts for different applications?
Just take lots of pics before you rip in. Your going to need a Mitivac 8500 too you have to check the pressure and vac to see if its airtight after the rebuild.
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