MS441 failure and diagnosis.

[Andyshine77]

I've been working on a local tree companies saws the past few weeks, a few 200T mostly.

Here we have a well used 441 that was said in their words, the saw would run for a bit than stop, and it was hard to restart, it may be seized.

Here is the first thing I saw under the filter cover. Something has been missing for a long time.

There was as much dust inside the carb bore and intake boot as there was on the outside of the saw.

The dirt ingestion caused the ring pin to pop out.

This didn't cause the saw to stop running, it must have sounded like #### and the saw likely didn't run all that well.:help: Did they stop running the saw at this point? Nope! They ran it just long enough to allow the ring to rotate and catch in the exhaust. This pic is of the exhaust side of the piston. Note the other ring pin, on the 441 one pin is near the exhaust the other in the intake like normal.

I'll be going over the saw and replacing the top end. The bottom end seems to be in order, but I'll flush the case and replace the seals and make sure the case is air tight.

 

[Justsaws]

Hmmm, this saw sounds different.
I better use it some more.
Huh, runs for a bit and then stops, that is weird. :msp_sad:
I better run it some more.
Well I be darned, it does not want to start up very easily:msp_sad:
, stupid Stihl saws,:msp_angry:
I knew we should have bought Huskys.
I better run it some more.

 

[morewood]

Occasionally I will work on someone else's guns. If I get it in pieces or put back together wrong I add in an unlabeled charge.......known as an idiot charge. This saw qualifies for multiple unlabeled charges.

Shea

 

[Anthony_Va.]

Some people just can't seem to quit while they're ahead. The people I work for are like that.

For instance, the Discbine we mow with was squealing. It had been since last year. Well, no one would look at it and it finally locked up. It was a bearing in the rollers. It destroyed the chains, bearing seats, and much other stuff. Almost totaled it out.

Another one, they have a JD Gator. The boot on the front axle was busted. They know about it and still refuse to change this 20 dollar boot. Well, it ends up filling with dirt and destorying the axle bearing. The peice is only sold as a complete unit. 400 bucks for not changing a 20 dollar boot. Bad thing is, this same thing has happened three times now. :mad2:

I'm the kind of guy that will just stop and tear down/fix a small problem before it gets out of hand. I can't understand why some people like to let things do until they destroy it.

 

[Stihlman441]

Nice i dont think the 441 was the failure.:rolleyes2:

 

[wkeev]

That looks like some of the saws I've got from a local tree service . Run'em till they quit I guess . PM me if you need a used P/C . I have one from a saw that I have for parts . I bought it for some parts I needed to fix one that I have . I need some more parts and pieces if he doesn't want to fix .

 

[SawTroll]

Nice i dont think the 441 was the failure.:rolleyes2:

No, but using only one piston ring might have stopped it before all that damage was done - and made the saw run a bit better before that point.....

 

[MCW]

I've got a new aftermarket P&C here if you need it Andy.

 

[TK]

What's missing? You say you removed the air filter cover.... then there's the air filter..... Forgive me, I don't know these saws but it looks like you've got the necessary items there.

 

[Fish]

No, but using only one piston ring might have stopped it before all that damage was done - and made the saw run a bit better before that point.....

The Husky's burn up quicker and leave a better looking corpse!!!!

 

[young]

What's missing? You say you removed the air filter cover.... then there's the air filter..... Forgive me, I don't know these saws but it looks like you've got the necessary items there.

the thumb screw which holds the air filter tight is missing. loose filter was letting all the junk in.

 

[rupedoggy]

Andy be happy there are folks like this. It pays some of your bills.
How do you determine that a dirt ingestion problem caused a ring locator pin to pop out? I can't see the connection. Saws will run a long time without a filter but not long without a pin, where there is suppossed to be one.

 

[Tzed250]

No, but using only one piston ring might have stopped it before all that damage was done - and made the saw run a bit better before that point.....

So the best engineered saws only ever use one piston ring?

 

[Andyshine77]

Andy be happy there are folks like this. It pays some of your bills.
How do you determine that a dirt ingestion problem caused a ring locator pin to pop out? I can't see the connection. Saws will run a long time without a filter but not long without a pin, where there is suppossed to be one.

I put two and two together. Sure I've seen saws run a long time without a filter, and some older saws pretty much didn't even have a filter in the first place. I will guess that it was a compounding issue, but dirt ingestion being the main cause of the failure. Excessive skirt wear would cause quite a bit of vibration, and who knows what that much dirt would do under and around the ring. Lubrication didn't seem to be an issue, and I saw no signs of excessive heat.

Few more pics.

This made some noise.:msp_w00t:

 

[roostersgt]

"Good" used OEM P/C on ebay for $70 OBO. Hose it down w/oven cleaner and it'll look like new. There is also a case and other parts group in another listing. I know someone was looking for a new case last week.

STIHL MS 441 CHAINSAW OEM CYLINDER PISTON 361 440 | eBay

Another "good" used OEM p/c from a site sponser for $80.

http://store.chainsawr.com/products/stihl-ms441-chainsaw-piston-and-cylinder-kit