Dolmar 5100s died

[jeepstrapped]

This weekend was out cutting firewood and the saw died in the middle of a face cut.

I had been using it for a little over an hour felling and cutting up a 30' tree and it ran fine without any problems.

Got to the next tree and it just died while making a face cut.

I use 91 octane and mix with Stihl synthetic mix, the gas I was using is at most two months old. I also use stihl winter weight bar oil.

I pulled the spark plug and it has spark, I put my thumb over the spark plug hole and feel compression on stroke. If I pull the cord a few times without the spark plug in I get gas-mix in the combustion chamber.


My thought was the gas, so I got a fresh 2 1/2 gallons of 91 octane and mixed it with the Stihl synthetic mix, poured out the old gas and replaced it with the new gas and it still won't start.

I use the saw every weekend, have had it for about 7 months.
I always do the same thing, start it, idle it down and let it warm up for a couple of minutes before I start using it. Usually as long as it takes for a marlboro break.

I can't figure out why it won't start?

Anyone else have this issue, or recommendations on what to look at?

 

[blsnelling]

Pull the muffler and tell us how the piston looks. Do you have a compression guage?

 

[jeepstrapped]

I need to get a new driver to get the bolt out that is down by the dog, I tried to use the allen wrench that came with the saw but it seems to be a little light and the bolt seems stuck, so I stopped before stripping the head.
I can borrow a compression tester and check the compression, what should I look for in numbers, over a 100?

 

[blsnelling]

What should I look for in numbers, over a 100?

Anything less than 140 is indicative of a problem. 100 PSI likely wouldn't even start.

You can also remove the spark plug and look through to the exhaust side of the cylinder wall. You'll need a bright flashlight.

 

[scotclayshooter]

Anything less than 140 is indicative of a problem. 100 PSI likely wouldn't even start.

I have a 262XP that was only showing 130 and it started and ran fine.
My oldest FS250 is also down at 130 and still runs great!
Does the de-comp not put the compression below 100?

 

[Edge & Engine]

I have a 262XP that was only showing 130 and it started and ran fine.
My oldest FS250 is also down at 130 and still runs great!
Does the de-comp not put the compression below 100?

No Decomp on these. I have seen saws run and in use at minus 100PSI, they don't run very well though.

 

[Brian S]

Jeez! I'm starting to wonder about the 5100, I really hope this one turns out to be a simple problem but it seems like there are more and more of these things failing.

 

[Taxmantoo]

Quick and dirty compression test:
Put the plug back in, and pick the saw up by the starter rope. The saw will drop as it turns over, kachug, pause, kachug....
How many seconds does it take between compression strokes?

 

[jeepstrapped]

What I was able to see when looking in the chamber from the spark plug hole is that there is oil present on the top of the piston.
I do know that I haven't run straight gas through it, I'm paranoid about that and have labeled gas cans so I don't confuse chainsaw gas and mower gas.

But yeah, I'll have to get the muffler off and look at the piston.
But I get the opinion, from the seat of the pant or thumb, test that there is decent compression and I can't detect any leak-down.

Put thumb over plug hole pull rope slowly, so the compression doesn't push my thumb off, and the pressure doesn't diminish over time it just holds until I remove my thumb. Again - just a seat of the pants, or thumb, observation.

And the saw ran fine for a couple of hours previous to this. no noticable lag or lack of power. It just quit when I had it on it's side.

Note: I am at work now and can't get to the saw to work on it.

 

[THALL10326]

This weekend was out cutting firewood and the saw died in the middle of a face cut.

I had been using it for a little over an hour felling and cutting up a 30' tree and it ran fine without any problems.

Got to the next tree and it just died while making a face cut.

I use 91 octane and mix with Stihl synthetic mix, the gas I was using is at most two months old. I also use stihl winter weight bar oil.

I pulled the spark plug and it has spark, I put my thumb over the spark plug hole and feel compression on stroke. If I pull the cord a few times without the spark plug in I get gas-mix in the combustion chamber.


My thought was the gas, so I got a fresh 2 1/2 gallons of 91 octane and mixed it with the Stihl synthetic mix, poured out the old gas and replaced it with the new gas and it still won't start.

I use the saw every weekend, have had it for about 7 months.
I always do the same thing, start it, idle it down and let it warm up for a couple of minutes before I start using it. Usually as long as it takes for a marlboro break.

I can't figure out why it won't start?

Anyone else have this issue, or recommendations on what to look at?

This saw is only 7 months old and used only on week-ends, do nothing. My bet is its fried. Most saws that drop dead in the middle of a cut are usually scored. Its under warranty. Take it back and let the dealer find out what is wrong. Did you buy it local or through the mail?

If your really curious remove the muffler and have a look at the piston but don't go disassembling the entire saw, that may void your warranty...

 

[blsnelling]

This saw is only 7 months old and used only on week-ends, do nothing. My bet is its fried. Most saws that drop dead in the middle of a cut are usually scored. Its under warranty. Take it back and let the dealer find out what is wrong. Did you buy it local or through the mail?

If your really curious remove the muffler and have a look at the piston but don't go disassembling the entire saw, that may void your warranty...

And there is best advise you've been given. +100

 

[jeepstrapped]

I got it through a dealer in Sioux Falls, 60 miles north of where I live.

I was debating that option in my head, take it back to him and let the warranty cover it, or drop it off at a chainsaw repair shop on the way to work and see what the issue is.

 

[THALL10326]

I got it through a dealer in Sioux Falls, 60 miles north of where I live.

I was debating that option in my head, take it back to him and let the warranty cover it, or drop it off at a chainsaw repair shop on the way to work and see what the issue is.

Well if your really curious you can remove the muffler and most likely see what happened. Other than that I wouldn't do anything else to it. Makem stand behind it..

 

[spacemule]

Get some Stihl badges and put on it and take it to Tom.

 

[THALL10326]

Get some Stihl badges and put on it and take it to Tom.

That will work,

 

[blsnelling]

That will work,

I think that's an invitation, hint, hint.

 

[jeepstrapped]

I could get stihl badges to put on it, take it to the local Ace and the 18 year old behind the counter would probably not be able to tell the difference.
Heck, I could even try for a trade up to a 660 :greenchainsaw:

 

[THALL10326]

I think that's an invitation, hint, hint.

LOL, I'd love to tear that saw apart and see what she's made of, I've never seen inside a Dolmar 5100.

 

[THALL10326]

I could get stihl badges to put on it, take it to the local Ace and the 18 year old behind the counter would probably not be able to tell the difference.
Heck, I could even try for a trade up to a 660 :greenchainsaw:

Welp if your really curious you can do this. Pull the spark plug, lower the piston all the way to the bottom of the cylinder, get a flashlight and look closely at the exhaust side of the cylinder through the spark plug hole. If you see alot of scratches on the wall your cooked. If it is tant no biggie, use that warranty..

You can also use the old pull rope trick. Hold the saw up at least to your waist. Grab the pull rope handle in one hand and hold it and lower the saw with the other. If the saw has no compression it will fall as fast as you can lower it, the pull rope will extend right out. If its got compression your holding the pull rope will hold that saw up even though your trying to lower it.

 

[spike60]

I got it through a dealer in Sioux Falls, 60 miles north of where I live.

I was debating that option in my head, take it back to him and let the warranty cover it, or drop it off at a chainsaw repair shop on the way to work and see what the issue is.

I would take it back to the place where you bought it, not the local shop, which I assume is not a Dolmar dealer. He can't really do anything that you can't do yourself ie checking the piston for scoring. If it is scored, it's going to have to go back to the Dolmar dealer anyway.

If it is scored, the first place I would look is to see if the carb bolts are loose. I've seen this take out a couple of Dolmars. (1-5100 and 1-7300)