MS440 sprocket question

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The parts manual lists two clutch side crank oil seals for the one in the drawing. How do I know which I need?

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My IPL shows #18 for all models except #2 below, and #19 for the MS440-D. Someone else will have to say which saw that is - I'm clueless.

(1) MS 440, (2) MS 440-D, (3) MS 440-N, (4) MS 440-W, (5) MS 440-Z, (6) MS 440-RZ Magnum, (7) MS 440-VWZ Magnum Arctic, (8) MS 440-Z Magnum
 
OK, so I put a digital caliper on the clutch side crankshaft and the smallest measurement I got was 11.93mm. Can I run this crank as it is? The repair manual does not state dimensions. I'm guessing it is supposed to be 12mm.
That is about .0015" on each side of the diameter (.003"total). Crankshaft stubs are normally heat treated to harden them (case hardening?). I know that the hardening doesn't go very deep. Some others here might be able to contribute more. The telltale is that the drum may rock back and forth too much. Check for this with the new OEM bearing and new OEM drum.
 
@wseibert Put up a photo of the edge of your old sprocket so we can see the amount of wear. If it is too bad the chain is probably toast and the bar may be questionable. Sprocket and chain wear together so if one is worn it will quickly wear out the other one if it is new.
 
@wseibert Put up a photo of the edge of your old sprocket so we can see the amount of wear. If it is too bad the chain is probably toast and the bar may be questionable. Sprocket and chain wear together so if one is worn it will quickly wear out the other one if it is new.
I'm replacing the sprocket. I don't know how much life the chain and bar have left - probably not much, considering all the evidence of abuse. I'll see once I get it rebuilt and running.
 
I'm replacing the sprocket. I don't know how much life the chain and bar have left - probably not much, considering all the evidence of abuse. I'll see once I get it rebuilt and running.
A chain that has been ruined by a worn sprocket will quickly ruin a new sprocket.
 
What do I check on the chain for wear? The drive links? How do i know if they're worn?
The main issue is chain stretch which will cause an uneven distribution of load on the sprocket. There is no easy way to check this other than to measure the distance between an odd number of rivets and compare with the chain pitch specification. For bicycle chains (1/2" pitch) the wear limit is 0.125" over 1 foot of chain (1% stretch).

Scratch all that. The bar is shot, the sprocket is shot, so the chain is shot. I just need to accept this and move on.
The main thing to check on the bar is the width of the groove (gauge). It should be no more than about .004" larger than the marked gauge to keep the chain from flopping side to side.

Good idea to change it all and start fresh and continue with proper maintenance.
 
Now I'm in Stihl parts purgatory. Gave a list of parts needed to the nearest parts supplier, and they were going to get me a quote yesterday. When I called yesterday, they were having difficulty sourcing a couple of the parts. Still waiting.
 
Ok, so one of the bar studs was flattened by the bar on the top edge, probably from a previous owner pushing really hard on the bar with a dull chain. I ordered an OEM bar stud and the side cover wouldn't fit on it. I had to grind it down to make it work. In the photo, the cover is off but the bar and chain are on. Stud on the right came with the saw, stud on the left is the new oem one. WTF?
20231202_160453.jpg
 
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