ms441 rebuild, box full of parts

[mtnwkr]

I responded to an add on Offerup and picked up this ms441 for dirt cheap. The guy's story was that he got it with the bad P&C, started tearing it down and lost interest.
Piston is definitely bad, cylinder might be savable, I'll get a picture for you all to be the judge of.
I've never torn a saw down this far and this one looks a lot more complicated than the older saws I've worked on. The only thing I've found missing so far is the handle for the pull starter. When the compression went the original owner must have pulled the rope till it broke trying to start it..
I assume it'd be best to replace the crank seals? Never done that but I learn quick. All the rubber parts I've inspected look good.
It has the M-tronic carb, I've never dealt with one of those.. Shouldn't it have stopped the saw from burning up?
If I put the saw together again, do I have to take it to the dealer to get it tuned? I'm still on the fence about building this or parting it out. It looks in pretty good shape under the oily mess.
So, Piston and rings, possibly cylinder and crank seals. Anything else I should replace while I'm in there?

 

[mtnwkr]

Here's some more pics.
I noticed just now while taking these that the piston looks possibly damaged, like a piece of the ring broke off and bounced around. I don't feel any deep nicks in the cylinder though. What say you all?

 

[Canadian farm boy]

Definitely looks like a worthwhile project. I'd be fixing it. The piston and ring for sure. I always do crank seals on any rebuild. Gotta figure out what caused the original failure and fix that too.
The cylinder looks like it should clean up but it's hard to tell from just a picture.

 

[lwhaples]

Looks like a good box of parts to play with.

 

[Frogfarmer]

No need for the dealer to tune the saw. Definitely want to check and clean the carb. Even though its electronic controlled it still has diaphragms and screens to go bad or clog. Besides that put it back together, pressure and vac test,and make some chips.

 

[stihl_head1982]

By the looks of the one picture of the piston you may have something down in the crank case or lodged in a bearing.
I'd be afraid it would resurrect itself after a top end rebuild and reassembly. It would be my preference to split the cases.
But I'm a stickler for that kind of stuff.

 

[mtnwkr]

I spent probably 8 hours over the last few days cleaning and reassembling so I could figure out what was missing and where things went. I found a great build thread by Mastermind that helped immensely. I've never dealt with a saw this dirty! Dried oil and grease built up on everything, mixed with dirt, sap and dust. Only missing a few nuts and bolts and starter handle/rope.
There's a tab broke off the bottom of the starter cover but no other damage.

I figured out what put that mark in the piston. I heard something rattling around in the muffler and dumped out a perfect little piece of ring that matches that mark perfectly.

Did the ring break apart because the saw was overheating or did the saw overheat because the ring came apart?

 

[stihl_head1982]

Taking shape! Congratulations!

 

[lwhaples]

Clean! That came out good. What are you cleaning with?

 

[mtnwkr]

Mostly SimpleGreen and some WD40. Some Pieces were brought in and soaked in a hot sink with dishsoap overnight. Lots of compressed air and elbow grease too.

 

[TJ the Chainsaw Mechanic]

Least yers still has the handle. lol We didn't have any used ones at the shop so I ordered one up....Thank God I get a big discount! lol I'm rebuilding the carbed version of this model.

 

[CR500]

Can't wait till mine is complete again.


Sent from my non internal combustion device.

 

[mtnwkr]

Took a try at cleaning the jug tonight. I think I did ok for my first try. Next time will be much faster!

 

[mtnwkr]

Put the highway piston and rings in tonight. Spent all evening getting the carb, new handle and rope and everything put back together. Excited to see if it'll start I filled the tank up with gas and then watched it all leak out from a bad cap.
I took off the air cleaner and dropped a few drops of Trufuel in the carb and two pulls later, sure enough it popped! Pulled again and it idled for a second. Dropped a few more drops in with the dropper and a pull later I was idling!
I'm pretty thrilled, this is my first time replacing a piston and cleaning a bad cylinder. This started as a box of parts and I wasn't too sure I could get it put back together let alone get it to start.
I still have more to do but now I have some confidence that my time isn't wasted!

 

[CR500]

Post up on the maxflow fitting if you get a chance

Sent from my non internal combustion device.

 

[mtnwkr]

Well, Crap. I got a fuel cap and started it up this morning. After a few seconds I heard a quick death rattle and the saw stalled. I could turn the flywheel a little in each direction but something was jamming up in there. The good news is I can tear this thing down in under ten minutes now .
When I was installing the piston clips yesterday I heard the usual *ping as one of the clips became instantly non-existent. I looked around for a bit, turned the saw over and shook it to see if it dropped in and then went on with the install with my backup.
That little ring WAS in the case, it chewed the skirt off the piston and damaged the cylinder. I vacuumed out a couple chunks and flushed the case with WD40. Bearing still feel tight and smooth.
Should I replace the bearings, do I need any special tools? Do I have to split the case to do so?
Thanks for y'alls help so far! I have less than $140 into this so far so a new P&C isn't that big of deal I guess.

 

[lwhaples]

Wow,that's hard to look at.You did well to put it back together from a box.You sound positive,that's a good thing.

 

[cease232]

Bummer man. I'd saw the safe bet is to replace the bearings with all that metal floating around in there. Yes you need to split the case. Many people split cases with just heat.


Sent from my iPhone using Tapatalk Pro

 

[mtnwkr]

Got all my parts put back together today. Vac test failed, pressure test with some simple green showed my seals to be good but the decomp valve leaking around it's base and where the plunger goes in/out. Got a delete plug for $6 and fired it up. Started up no problems! Cut a few cookies out back and seems to run well. Compression at 150psi, I'm assuming this will get better with some use?

Family photo.. My 026 and 036 got a good cleaning and new bars over the winter.

 

[CR500]

max flow filter fit?