stihl 041 stalled and wont restart

[vasten]

My log load arrived the other day and I got all excited. Got my gas all mixed up, filled up my bar oil. and started the saw. I made about 20 cuts when she stalled out, and that was the end of it hasn’t started again.

The saw is a 041 AV, when it stalled out I checked the kill switch to see if I bumped it and almost burned my finger it was so hot. Obviously let the saw cool off (and me too ) for a few days. When I went back out I noticed one of the vaccuum lines from the carb to the front of the saw was off. I reattched that and nothing. Took it to my local Stihl dealer and we replaced that line and a new air filter, and spark plug. I am getting spark, checked by first grounding plug to side of saw and pulling over, then with it in the saw and a plug tester. Compression test shows it pulling 90 lbs of compresson. When investigating further noticed that muffler had litterally come off, I put that back on and still nothing.

I have put gas in the carb, directly into the cylinder through plug hole and even tried either in both of these ways and still wont pop. It has nothing going on.

The saw is sitting on my buddy’s work bench now, waiting, looks like today we are going to try to get to the coil. our thoughts are that the coil is not putting out a strong enough spark consistantly. thinking it could have gotten fried when it got hot. Also all of the wires out of the engine are in decent shape, no signs of cracks or melting. The other option is that the engine is just worn out, and rings and etc are shot, but if so, then not thinking it would pull 90 lbs of compression.

When I was cutting with it, it smoked like a mother, I just figured it was the gas/oil mix and it would clear, and the casing temp would make sense from the muffler being off, inside the machine and dangling there. If it couldn’t vent out through the muffler it was venting inside the casing in turn heating that up.

Before I tear the saw up anymore any suggestions would be appreciated, thank you

 

[Fish]

When the muffler was off, did you look at the piston? 90 pounds ain't much.

 

[pioneerguy600]

As Fish said above post, 90 lbs is not much, it should have over 120 lbs to start and run half decently and 140 - 150 would be a lot better, easier to start and good power while in the cut. You need to tear it down to see the condition of the cylinder and the piston. A new set of rings may bring the comp up enough to get a few more years of running out of it. If the piston or cylinder is scored then it is costly to have them replaced, you can do it yourself for much less if you have a little mechanical ability.
Pioneerguy600

 

[vasten]

I checked the wiring and it appears to be fine, no marks, knicks, or melted sections. It looks to me that it is all coming back to the compression. One thing I am wondering is if the compression read low because there was no back pressure from muffler. I didn't realize the muffler was off until later on.

Piston was shiney and decent looking from what little I could see through the exhaust port. Not that is only one small section of the entire piston and it doesn't take much to kill your compression.

 

[taxidermist]

It would not make any difference with the muffler as it is pretty open and your compression happens when it is above the exaust port.

From your other post on hearth I think you had a lean melt down. pull the muffler and look for scoring on the pistion.

Rob

 

[mnsnow]

The vacuum line may have came off while you were cutting -

causing the saw to run lean and damaged the piston and cylinder.

end result - low compression.

You may have to pull the cylinder - maybe a piston ring is broken.

 

[vasten]

son of a :censored:
The gas station does sell 10% ethanol mix, never dawned on me. I remember reading that when I was filling up the tank. Creature of habit went to were I always get my gas.

I was blaming that opti2 universal mix oil. I have used it prior and the guys at the rental/hardware shop gaurenteed it wouldn't hurt the engine. But the ethanol would make more sense.

When I first got this saw the compression was so high, I litterally yanked it out of my hand trying to start it. a huge difference now.

Well looks like the head will be coming off and checking the rings and praying the bearings are still good.

 

[vasten]

oh and any suggestions for a replacement saw? I cut about 30 face a season, and for cutting some trees on my land.

Buddy of mine who is more into saws than I am said the 041 would be the absolute smallest saw to go with.

 

[PaladinMan187]

As Fish said above post, 90 lbs is not much, it should have over 120 lbs to start and run half decently and 140 - 150 would be a lot better, easier to start and good power while in the cut. You need to tear it down to see the condition of the cylinder and the piston. A new set of rings may bring the comp up enough to get a few more years of running out of it. If the piston or cylinder is scored then it is costly to have them replaced, you can do it yourself for much less if you have a little mechanical ability.
Pioneerguy600

An old drag racer once taught me that ANY motor with a spark plug needs 100 psi in order to fire the cylinder. Thus, why do you think the end of *acceptable compression* on a leakdown tester is 100psi?

To the original Poster, it sounds like the SAME thing my buddy did with his beloved 046. Pull the muffler and see what it looks like. that will tell the tale.

 

[blsnelling]

Were you running the Opti2 at 100:1?

 

[pioneerguy600]

An old drag racer once taught me that ANY motor with a spark plug needs 100 psi in order to fire the cylinder. Thus, why do you think the end of *acceptable compression* on a leakdown tester is 100 psi.

?

 

[vasten]

Were you running the Opti2 at 100:1?

Opti2 is universal there is no real mix ratio to it, it comes prepackaged for 2.5 gals.

 

[Brmorgan]

Every oil has an optimal mix ratio. 200 mL would give about a 50:1 ratio for 2.5 gal. of gas, so I would imagine that's what it is.

 

[vasten]

riddle me this....?

Ok guys I'm lost here, I had the saw on my buddy's bench with the recoil side of the casing off. I sent him the info that you provided me here, about the low compression and not likely to start etc etc. So I went to visit him yesterday and noticed the saw was put back together and ready to go. His way of saying if it needs to be torn down take it home to do it. So for spits and giggles I tried to start it and nothing same as before.

I went out to mow the lawn today and it was sitting next to the mower, and again giving it the old college try I gave her a rip and sounds like she wanted to start. Low and behold on the 4 rip she took off and ran. I let her come up to temp and shut her down. Mowed for a while and came back, first pull she took right off again. Shut her down again. Let her sit for a while and went back again and sure enough she started again. I went over to a piece of cherry about a foot across and she went right through it like butter.

I could say the coil was breaking down under heat, but wouldn't explain the it not starting when cold. I could say the rings were bad and low compression but not positive that would explain it all right now either. Could be we did the compression test wrong, or the muffler being off affected it I dont know.

I am wondering now if that little vaccuum tube that fell off needed time to rebuild vaccuum in the carb to get her going again. If so if a 10 cent piece of plastic caused and cured this then I am amazed.

Anyways guys I thank you for your help I really appreciate it. And any suggestion you have now would also be appreciated.

 

[Brmorgan]

If your impulse line (what I assume you are referring to as a vacuum line, same difference in the end) fell off, the saw would literally be impossible to start. If it just had a crack or small hole where it could suck air, it would make it much harder to start but not necessarily impossible. It could also cause the engine to run lean and burn up - which might explain the low compression.

However if you got it to start in four pulls and it cut some hard cherry acceptably, I'm pretty sure that the 90 lbs reading is wrong. Brad Snelling started a thread a while back called something like "The right kind of compression tester" or some such. The long and short of it is that you need one that screws into the plug hole (not those garbage rubber tip fit-all setups) and it must also have a schraeder valve right at the tip of the line where it enters the cylinder. The reasoning is that small engines like chainsaws do not have enough displacement to keep the air in the line between the cylinder and gauge compressed between piston cycles to ensure an accurate reading.

If it had been run for any length of time with the muffler actually off, then you could have any of a number of problems due to the excess heat escaping where it shouldn't. Come to think of it, given that the exhaust port on the 041 is directly under/beside the carb assembly, chances are that the carb overheated bigtime and you got a real badass vapor lock in the intake, which would explain why it'll run now after sitting a few days. On a similar note, check the fuel tank vent, because if it isn't venting properly it can cause the same symptoms.

I would recommend getting a carb rebuild kit at any rate- if it did indeed get that hot, who knows what damage it could have done to the diaphragms and gaskets in the carb. The exhaust could have also melted the manifold block that sits between the carb and the cylinder - be sure to check that it isn't misshapen and causing an air leak.

Probable chain of events that I see here is:

Muffler bolts came loose --> impulse line swelled due to exhaust heat and fell off --> saw stalled due to fuel starvation --> carb vapor locked due to exhaust heat --> possibility of piston/cylinder damage due to lean mixture.

If the muffler had not "fallen off", this would sound like a classic straight-gassing or ethanol burnup, but I think the above is more likely, though possibly with the same end results.

 

[vasten]

Well it may be hard to say now, but I think that your scenario sounds pretty accurate.

I took the saw out yesterday, and after starting it several times, and checking it out making sure it would idle and rev up etc. I went out and got some non-ethanol gas filled her up and started cutting to see what would happen. She was a cutting machine, I cut for close to two hours, cherry ash and maple. I ran her out of gas on the second or thrid tank and that was it, seized right up. I guess due to not knowing any better, but if it runs and runs strong work it right, and see what happens.

So anyways time for a replacement saw. This saw could be a good looker if put back together, but it doesn't have a chain break, a feature I really like. I thought about keeping it for parts, and trying to locate another one. But concerned with a used saw and possible mistreatment leading to a lot of money invested in a possible short lived saw.

Thanks for all your input, and I will be starting a string for a replacement saw.

 

[mountainlake]

Sounds like a lean sieze from the start, stuck the ring in the piston which loosened up later and it ran again untill it lean siezed again. Steve

 

[MS460WOODCHUCK]

Well it may be hard to say now, but I think that your scenario sounds pretty accurate.

I took the saw out yesterday, and after starting it several times, and checking it out making sure it would idle and rev up etc. I went out and got some non-ethanol gas filled her up and started cutting to see what would happen. She was a cutting machine, I cut for close to two hours, cherry ash and maple. I ran her out of gas on the second or thrid tank and that was it, seized right up. I guess due to not knowing any better, but if it runs and runs strong work it right, and see what happens.

So anyways time for a replacement saw. This saw could be a good looker if put back together, but it doesn't have a chain break, a feature I really like. I thought about keeping it for parts, and trying to locate another one. But concerned with a used saw and possible mistreatment leading to a lot of money invested in a possible short lived saw.

Thanks for all your input, and I will be starting a string for a replacement saw.

Sounds like your in need of a MS361 that I have with only 7 Tanks of fuel through it. PM if interested.

 

[Motodeficient]

Your saw will probably bring over $100 on ebay as a parts saw, which would be a good start towards a 372xp

 

[vasten]

Your saw will probably bring over $100 on ebay as a parts saw, which would be a good start towards a 372xp

I noticed that, I also saw where a recoil and start was bringing in over 75.00, then add in carb, handles, casing etc.

So I have some options with it, but man is it killing me to see that log pile just sitting there.