MS440 sprocket question

[ZeroJunk]

I'm thinking that if you held an MS440 wide open it might have enough power to overcome the chain brake. Maybe. But, just how dumb would you have to be ?

I work on these most every day, and if you throttle it up with the brake on nothing happens.

So, with an IQ of 20 you think the chain brake is on and snap it off.

 

[lone wolf]

The vacuum gauges that I'm seeing are being sold as brake bleeder kits - is that what I need to test vacuum and pressure?

Thanks

No you need vac and pressure like another posted said Mitivac 8500.

 

[bigbadbob]

how about some pictures behind the clutch drum and clutch.
TIA

 

[wseibert]

how about some pictures behind the clutch drum and clutch.
TIA

OK, so here are a couple of the clutch front and one of the back.







Here's the oil pump worm gear (looks ok...?) and spring:




The spring is big enough to slide over the worm drive. Not sure it is supposed to. And the end is broken off.

Here's the crank:



A couple of other details. The bar was so worn that there was not only a. lip along the entire thing on both sides which I ground off, but there was a small place on each side where the bar had delaminated and broken off along the rail. Also, and I wish I had taken a photo of this, the rear bar mounting stud had a flat top at the base, as if someone had been really pushing hard on the bar for a long time.

So, I wanted to run it without the clutch assembly and pour gas on the crank seal as has been suggested to test the seal. I took off the clutch, worm drive and sleeve, but could not get it to run. Got it to pop with the choke on, but it would not stay running. Reinstalled the clutch, and it started and ran fine.

Could this indicate a bad crank seal, as the clutch assembly is needed to seal the crank at that end?

Thanks again.

 

[SteveSr]

OK, so here are a couple of the clutch front and one of the back.

View attachment 1125703

View attachment 1125704

View attachment 1125705

Here's the oil pump worm gear (looks ok...?) and spring:

View attachment 1125706

View attachment 1125707
The spring is big enough to slide over the worm drive. Not sure it is supposed to. And the end is broken off.

Here's the crank:

View attachment 1125708

A couple of other details. The bar was so worn that there was not only a. lip along the entire thing on both sides which I ground off, but there was a small place on each side where the bar had delaminated and broken off along the rail. Also, and I wish I had taken a photo of this, the rear bar mounting stud had a flat top at the base, as if someone had been really pushing hard on the bar for a long time.

So, I wanted to run it without the clutch assembly and pour gas on the crank seal as has been suggested to test the seal. I took off the clutch, worm drive and sleeve, but could not get it to run. Got it to pop with the choke on, but it would not stay running. Reinstalled the clutch, and it started and ran fine.

Could this indicate a bad crank seal, as the clutch assembly is needed to seal the crank at that end?

Thanks again.

The worm gear is toast.
Drum is toast.
Clutch will likely need new springs.

More importantly, the crankshaft where the bearing disintegrated looks possibly galled. Get out your calipers and measure the diameter of the crankshaft stub in the middle of the bearing and at a point on the end where the bearing didn't ride and note the difference in diameter.

This engine has an air leak when the worm sleeve is removed so the engine won't run. However it makes it super easy to replace the seal so just replace it.

 

[wildwes]

The worm gear is toast.
Drum is toast.
Clutch will likely need new springs.

More importantly, the crankshaft where the bearing disintegrated looks possibly galled. Get out your calipers and measure the diameter of the crankshaft stub in the middle of the bearing and at a point on the end where the bearing didn't ride and note the difference in diameter.

This engine has an air leak when the worm sleeve is removed so the engine won't run. However it makes it super easy to replace the seal so just replace it.

Seals are easy enough to replace it is almost worth doing them as a matter of routine on saws with unknown histories. It isn't a big deal to do them.

 

[huskihl]

The heat damage is more likely from starting it with the brake on and letting it run in the high idle position for several minutes without clicking it down to an idle.

 

[wseibert]

Thank you all for your help. So I need a seal pulling tool - should I spring for an OEM one or are there good alternatives?

 

[wseibert]

The worm gear is toast.
Drum is toast.
Clutch will likely need new springs.

More importantly, the crankshaft where the bearing disintegrated looks possibly galled. Get out your calipers and measure the diameter of the crankshaft stub in the middle of the bearing and at a point on the end where the bearing didn't ride and note the difference in diameter.

This engine has an air leak when the worm sleeve is removed so the engine won't run. However it makes it super easy to replace the seal so just replace it.

I'll check the crankshaft next. I really hope it's ok.

 

[slowcar281]

Got any pics of the whole saw? That’s a shame someone did that to a 440. After you replace everything clutch and sprocket related definitely pressure test it and consider replacing the seals and impulse line. Take the saw down far enough to triple check the intake boot for cracks.

That saw will rip with a 16” bar.

 

[wildwes]

Thank you all for your help. So I need a seal pulling tool - should I spring for an OEM one or are there good alternatives?

If you're just doing the one set of seals, you can probably get by with some drywall screws. I have done a few that way and it works really well, you just have to be careful and patient. You can probably find some videos online showing how to do it.

 

[slowcar281]

Stihl makes an oem seal remover, and drivers to install the new seals and ensure the proper depth but I wouldn’t worry about buying them for one seal job.

Drywall screws work ok. Just be careful not to nick the crankshaft, and try to get the new seals to the correct depth like the ones you removed.

 

[Mad Professor]

I've seen a 026 melted like that from so much debris filling the whole area under the clutch cover.

Wonder it didn't catch fire.

 

[wseibert]

Next steps: check crank for galling (if it's no good, evaluate whether to move forward with this saw), remove and go through oil pump and rebuild with new o-rings, replace crank seal, rebuild with all new parts related to clutch, get vac/pump tool and test, tune carb (need a tach), sharpen chain (though it looks to have been cooked as well), cut wood and smile. Did I miss anything?

 

[wseibert]

Stihl makes an oem seal remover, and drivers to install the new seals and ensure the proper depth but I wouldn’t worry about buying them for one seal job.

Drywall screws work ok. Just be careful not to nick the crankshaft, and try to get the new seals to the correct depth like the ones you removed.

Thanks slowcar. The repair manual talks about using grease on the rubber lip and sealant on the outside edge of the seal when replacing. What kind of grease and sealant should I use? Can I get these at my local auto parts store, or do I need Stihl brand?

 

[slowcar281]

Thanks slowcar. The repair manual talks about using grease on the rubber lip and sealant on the outside edge of the seal when replacing. What kind of grease and sealant should I use? Can I get these at my local auto parts store, or do I need Stihl brand?

Any kind of grease will work for the lip of the seal. Using rtv on the outside of the seal is debatable. Some use it and some don’t. I personally use it.

Any auto parts sealer will work. Permeatex Red or Motoseal is fine

 

[wseibert]

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.

 

[slowcar281]

As long as there aren’t any rough spots where the bearing rides, it’s probably ok. Replace the clutch springs, drum, sprocket, bearing and worm gear and see how it runs and make sure it oils.

Then you can pressure test it and go from there

 

[Chevboy0167]

Might be in there somewhere....?

https://www.manualslib.com/manual/1302030/Stihl-Ms-440.html#manual

 

[wseibert]

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