Killed my Dolmar 5100S??

This is not looking good. I was cutting Osage Orange today and the saw started to cut out by itself. So I left the saw off and did other stuff. After about 20 minutes I could not start the saw - there was no combustion turn over at all on pulling the starter. It seemed just like vapor lock since the cylinder was dry, but after 2 hours the saw was cold, the cylinder would get vapor/fuel, but still no combustion on starting. I also noticed that it was slightly harder to pull on the starter - not a lot, just enough that it would not "free run" like it sometimes does. (Now I suspect piston drag.)

At home 3 hours later I still have same problem. I have tried a different spark plug, a clean filter, and visually checked the spark (seems ok). I do not have a compression tester but have just tried the thumb over spark plug hole test and it did not pop off. So that means low compression? I never did that test before so not sure what to expect.

So it sounds like something bad inside the cylinder. What should/can I test now? Or what part(s) need replaced?

I am mechanically handy, but haven't much time with 2-cycle engines, and do not have specialist tools. I'm guessing I need new piston ring, maybe new cylinder head, and I do not know about the piston.

The alternative is to find a local Dolmar dealer or other small engine place and have them do the work.

And I think I need a more powerful chainsaw for Osage Orange! That stuff is tough.

Pull the muffler off and look at the piston and cylinder...

You'll know immediately if there is any scoring and damage...

Gary

I now have a 5100 in the shop for warrantry repair. bought brand new about 3 months ago, ran fine for maybe 3 tanks full. took it back to the dealer and waited 3 weeks for a response regardless that I called 3 times, now finally got the answer that they approved to work on the saw. I am now thinking that dolmar saws are not all that good regardless of all the high regards towards this saw. About 8 years ago I bought a husky 372xp off the internet and never a problem yet with the saw never seen a repair shop yet,

GASoline...with the angled exhaust port it is hard to see, but it looks like there are small vertical scores on the piston at the exhaust port and maybe also on the cylinder wall at the exhaust port. The cylinder wall on the opposite side (at carb inlet) looks smooth. Without taking it apart I can't see more.

I've always thought my saw ran 'hot' temperature wise from new. I had a dealer check the carb settings, and I checked them too, and every time I checked it was running within rpm limits.

woodcutter...what was the problem with your saw?

After-thought: Osage Orange does not chip when cut, it turns to dust, even with a very sharp chain (which would nicely chip softer wood like Eastern Red Cedar). I've noticed some dust in the past inside the flock air filter and at the carb entrance. Since I was exclusively cutting Osage Orange this morning, I wonder if enough dust got past the filter to damage the cylinder? There was more oily dust than normal at the carb entrance when I changed the filter, even although the filter I removed was pretty clean. I've seen the Dolmar dust issue commented on this site before.

I dont know yet, still at the repair shop. I took it in because it would die in the middle of the cut when warm, let cool down about 1 hour and would start run fine until warm, then it got to where it wouldnt start at all, took to dealer and have not heard back except they will pay for the repair. I am now looking for a more reliable saw. maybe another husky or stihl or even a john deere.

Dolmar... :monkey:

We fried two 5100's. The first straight up seized and the second slowly lost power/compression and they were both under warranty. Myself and the dealer who just picked up the dolmar line felt it was a filtration problem as more than one occasion there was dirt inside the filter. Luckily my family over the years had bought a-lot of husky's off of him so he just gave us shop credit and now only special orders dolmar. I have heard from him that the 7900's he had ordered have been solid but none the less i'm done with Dolmar, but thats just me

I was talking to the dolmar dealer in the area about any problems they have seen with dolmar saws. He said the only problem was with the 5100. A customer had a saw lock up. Dolmar inspected it and found out the piston rings were not getting enough oil when run at speeds lower than full speed for cutting. He said this was only a problem with the 5100 and this was not a problem on the bigger saws. He has had only satisfied customers with the 6400, 7300 and 7900. That was another reason why I purchased the 7900.

Are you guys trying to make me change my mind on a Dolmar 510 or 5100s?

I was excited thinking I finally made up my mind but now your making me sketchy!
I changed my mind from a stihl ms260 pro due to price and go with the Dolmar.

Now I am just confused again!

fsfcks said:

The alternative is to find a local Dolmar dealer or other small engine place and have them do the work.

And I think I need a more powerful chainsaw for Osage Orange! That stuff is tough.

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Where you at in Kansas? When I had my 7900 i searched for Dolmar dealers, and found a few, but I called them and they all sounded lame. They had never heard of a 7900 or a 5100.

I cut a cord and a half of Osage orange today, and damn right that stuff is tough. If it is dead wood, no chips with this stuff, its all fine dust. Hell on chains and air filters.

skinnykid02 said:

Are you guys trying to make me change my mind on a Dolmar 510 or 5100s?

I was excited thinking I finally made up my mind but now your making me sketchy!
I changed my mind from a stihl ms260 pro due to price and go with the Dolmar.

Now I am just confused again!

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I've heard a lot of guys on here just talk about cuttin and cuttin with em with no problems. I wouldn't be afraid to spend the xtra on a time tested saw like the 260 if moneys not the issue though.

In my minds way of thinking..

If dust in the cylinder was the issue.. The scoring would be on the intake side, not on the exhaust side.

My Makita/Dolmar has been a solid runner for a short while. Only time will tell. Of the thousands of saws they put out, some may have problems other saws have. Bad carb boots, fuel lines, etc.

ericjeeper said:

If dust in the cylinder was the issue.. The scoring would be on the intake side, not on the exhaust side.

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Yup, scoring on the exhaust side is more likely from a lean condition or a fuel issue like ethanol gas.

Bowtie...I live in south Kansas City (near Overland Park) but my land (and trees) are west of Ottawa, near the Franklin/Osage county line. The pastures I am trying to restore (clear) have lots of Eastern Red Cedar, Honey Locust, and of course Osage Orange. I will have plenty of firewood if I can cut it

skinnykid...What wood are you cutting? My 5100 loved softwoods like Eastern Red Cedar and Elm. I now think it might be under-powered for Osage Orange, which is almost stone (lots of silica). That was running .050" 3/8" chain on a 16' bar. Even when I get my 5100 fixed, I'm now looking at getting a 70cc saw for Osage Orange.

Re the scoring. Since I haven't taken it apart, and the spark plug and exhaust port are so small, I'm not certain exactly what is going on. Based on the comments here I'm going to take the saw back to the dealer and see if this is a warranty issue. The lack of oil to the piston rings at less than normal full cutting speed could be a possibility when cutting hardwood.

Thinking of the lubricating issues at mid throttle.

On a carb there are two jets, High and Low. A 2 stroke chainsaw engine is designed to either idle or run wide open. So it could be possible I suppose.

Eric...I always cut at full throttle, but in harder wood the saw does not always run at the same full cutting speed that it does in soft wood. I read the previous comments as applying to that situation.

fsfcks said:

Bowtie...I live in south Kansas City (near Overland Park) but my land (and trees) are west of Ottawa, near the Franklin/Osage county line. The pastures I am trying to restore (clear) have lots of Eastern Red Cedar, Honey Locust, and of course Osage Orange. I will have plenty of firewood if I can cut it

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Cool. I lived in Ottawa in 02' and 03'. I helped build all the bridges on I-35 from the LeLoup exit down to the hiway 59 exit by Wal Mart. I love burning Honey Locust, but the thorns are too much on some, lol. Sorry to hear about your 5100S, I had a deal in the works to trade my 026 for one. I use a 50cc for small stuff on hedge, but if Its over 12" I use the 361 or 044.

You west coast boys might laugh at that, but Osage Orange, especially standing dead, is crazy hard wood. Even fresh sharpened or new Stihl chain almost acts like a half dull chain in softer hardwood like hackberry.

grandpatractor said:

Yup, scoring on the exhaust side is more likely from a lean condition or a fuel issue like ethanol gas.

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+1 The majority of 5100 issues stem from E10 or greater gas. The Mobil in town is at 6% and have had no issues with their gas but the Gulf and the no name chain store brand both have tested very near 9-10% which is in the danger zone. We have recommended richening the fuel mix from 50-1 down to 40-1 and strongly recommend the use of Dolmar's Synthetic Oil.


Scott