Dolmar 5105 did not start - squirted oil into cylinder

[coloradotrout]

I have a 5105. I burned up a 5100 when presumably the dealer did not lower the high rpm. I used 91 octane gas. Dealer also said Opti oil was good and I could mix it at the Opti recommendations. After I got the 5105 from the dealer as a replacement, I ran with Opti, but at the same ratio spec'd by Dolmar. This last gallon of gas, however, I used the Opti ratio which is less oil.

I was cutting some hard dry wood yesterday, and the saw died. It would not start. The compression felt low. After a few hours, I pulled the plug, squirted in some 30 weight, and it fired up. After 24 hours I just fired it up again.

Any idea what is going on? Should I run it now? Or am I going to possibly damage something?

 

[nmurph]

There's a possibility you've scored another cylinder.

I would not run ANY oil at less than 50:1. I'm not sure what Opti oil specs, but there are claims by oils manufacturers that stretch credulity. You need to run 89 octane...more octane doesn't help you.

Pull the muffler and have a look, and report back what you see. The saw cutting off and then cranking when it cools down is a classic sign of a scored engine. Although there are other possibilities, if the cylinder is lightly scored and you continue to run it, you could turn a salvageable situation into one in which the P/C both will have to be replaced; don't run it until you figure out the if this is the problem.

 

[fordf150]

isnt the opti oil recommendations something like 80:1?

 

[fordf150]

Opti-2 1-gallon mix pouch - each 1.8 oz pouch mixes with 1 gallon of gasoline.

so thats 70:1. i would guess you scored another cylinder. time to pull the muffler and have a look.

 

[Termite]

There's a possibility you've scored another cylinder.

I would not run ANY oil at less than 50:1. I'm not sure what Opti oil specs, but there are claims by oils manufacturers that stretch credulity. You need to run 89 octane...more octane doesn't help you.

"Credulity" good one. I had to look it up.

 

[a. palmer jr.]

I usually run mine at 40:1. If people like to run their saws at 80:1 it's fine with me. I buy lots of worn out chainsaws that way..

 

[7sleeper]

Just fantastic how fast one can ruin a perfectly good saw! Although personaly I would contact opti oil and have them replace your equipment. If they guarentee 1:70 or 1:80 and it didn't work out then it's their fault and they will have to pay! For me as a consumer quite simple. I hope you have a insurrence for a lawyer so a court case won't cost you anything.

Good luck!

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[dugide]

was you using opti with the 5100 and does your dealer sell that oil?

 

[cus_deluxe]

this is getting dangerously close to another oil thread, so ill push it over the edge. Ive done golf course maintenance work for 15 years, 11 of that has been spent at golf courses that run amsoil at 80:1 in all 2 stroke OPE, as well as operating my own small landscaping business with my own trimmers, blowers, chainsaws... and have yet to see an oil-related failure. I know lots of guys say anything less than 50:1 is suicide but thats not true. old crappy gas kills more 2-strokes than ratios like 70:1 or 80:1. Can you do this with crappy dino-oil? no that WOULD be suicide, but quality synthetic at 70 or 80:1 is plenty for 98% of OPE use. Ported 390 milling? no. Heavy long cuts in mid summer? no. Johnny homeowner (haha get it) cutting some firewood, with fresh gas AND a properly tuned carb? All day.

 

[fordf150]

this is getting dangerously close to another oil thread, so ill push it over the edge. Ive done golf course maintenance work for 15 years, 11 of that has been spent at golf courses that run amsoil at 80:1 in all 2 stroke OPE, as well as operating my own small landscaping business with my own trimmers, blowers, chainsaws... and have yet to see an oil-related failure. I know lots of guys say anything less than 50:1 is suicide but thats not true. old crappy gas kills more 2-strokes than ratios like 70:1 or 80:1. Can you do this with crappy dino-oil? no that WOULD be suicide, but quality synthetic at 70 or 80:1 is plenty for 98% of OPE use. Ported 390 milling? no. Heavy long cuts in mid summer? no. Johnny homeowner (haha get it) cutting some firewood, with fresh gas AND a properly tuned carb? All day.

have seen plenty of landscapers running 80:1 (amsoil sabre in the pillow packs, they are advertised as 100:1) in the trimmers/blowers and they survive...IMHO simply because they turn lower RPMs and dont have near the load/ heat of a chainsaw. chainsaws are another story. Just because they survive doesnt mean i would recommend it or do it myself. I value my equipment and repairs(piston/cylinder) are expensive. Oil is cheap insurance. Although i think amsoil/opti both offer their own guarantee for products using their oil at their recommended ratios

 

[smokey7]

I know of two people that run amsoil pro 100:1 at that ratio in all air cooled ope and has for over 10 years he has no complaints. Also runs the saber outboard 100:1 in his pwc and outboard. He is not gental on equipment and he dont tune or retune anything . Me i use 100:1 in both versions pro and outboard for 6 years now it but mix at 40:1 or 50:1. I am scared to go leaner on the things i love. I have raced with it at 100:1 in a dirt bike but made more power at 32:1 if jetted and tuned for mix change.good job on oil thread tho. I would never break in a motor with high ratios like that. To me it is not run in till its had 10-20 hrs on it. I may be young but i still a little oldschool when it comes to this stuff. Chainsaws show the issues with thin ratios very quick mainly because they rarely warm up gently and spend there whole life wfo. In a air cooled enviornment with heavy load and high rpms and dirty conditions. Just my honest openion

 

[cus_deluxe]

oh man, thought i was gonna get more flame than that haha. sorry to hijack your thread OP, and sorry about your bad luck, but without more to go on its hard to say what went on and to what extent your saw has been buggered. Was it acting funny in any other way, like revving higher than normal or idling a bit funny? Honestly its way more likely that ur carb is out of tune or an air leak developed, rather than the oil (or lack thereof) had something to do with it. How many tanks did the 5100 have through it? how about the 5105?

 

[coloradotrout]

So much good info and some questions for me to answer:

The 5100 (blown) had very few tanks of gas - I'm going to say 2 or maybe 3. I went round and round with dealer and Dolmar. Finally dealer gave me the 5105 and pulled his Dolmar products off the shelf. They have not come back that I have seen. He has a few other brands of saws there now. One of the workers did mention something later about dropping the RPM might have helped". The 5100 had an exposed opening on the top of the carb as I recall. The 5105 has a foam piece covering that.

On the 5105 experience of late -- I now wonder if maybe my plug was loose? I had pulled it out awhile back and it looked good. I was not sure how tight to put it back in and did not want to strip. On Sunday when the saw died and would not start, I thought I heard air escaping on compression, but I could have been dreaming. Maybe pulling the plug -- adding 30wt to the cylinder -- and putting it back -- just sealed up the plug. The fact it started yesterday with all that 30wt burned up might be a good sign. When it died I just recall that pulling the rope had much less compression than usual.

How tight should the plug be? What in-lbs? or N-m probably in this case?

Ok -- so to pull the muffler -- just look for attaching screws and remove? How about looking into the plug opening?

FWIW -- I drained the existing gas in the saw, and added more opti to my remaining gas can and refilled the saw. I am using the 12 oz. bottle of opti that says it mixes ten gallons. I mixed one gallon at a time. On this last mix, my ratio was 1.2 oz. of oil to 1 gallon of gas or about 106:1. Until this last gallon I had been putting in 50% more oil so was putting in 1.8 oz of oil to 1 gallon or about 70:1. I'm going back to 70:1 at least. Maybe I should double the amount on the bottle which will be 2.4 oz per gallon or 53:1

I've put 3-4 gallons (not tanks) of gas through the 5105 using the 1.8 oz of opti to a gallon of gas (which looking at the little lines on the bottle is suppose to be 1.5 gallons of gas)

Just looking at the Opti website -- interesting that the 1 gallon pouches have 1.8 oz of oil, but the bottle I have has 12 oz and says 10 gallons. What is really interesting is the website *now* shows the "bottle" as having 13 oz of oil instead of the 12 oz bottle I have. 13 oz equates to 98:1, whereas the 12 oz was 107:1

Is 50:1 going to do any harm? Any downside? Because $2 per gallon vs $1 per gallon is really really cheap insurance.

 

[cus_deluxe]

First, the generally accepted rule of thumb is to never "break-in" a saw (or any engine for that matter) on synthetic oil. its good to run dino-oil (conventional) for the first 3-4 gallons of fuel through the engine, which helps seat rings and mate the surfaces. Ive never heard of an engine burning up from running only synthetic from the beginning but its not great for it.

 

[fordf150]

40:1 with whatever your choice of oil is. very cheap insurance.

T27 torx is all that is needed to pull the muffler. remove the 2 bolts that go in from the sides and the 2 in the front of the muffler. remove that bracket which will expose 2 more screws that are holding the muffler on. take pics of the piston looking through the exhaust port and post them up. any scratches or grooves on the piston are a bad sign.

 

[cus_deluxe]

And yes, checking the plug would be a good place to start. i dont know what the torque should be, i just do finger tight as far as i can go, then it usually only needs less than another 1/4 with a ratchet. too tight can cause make it really hard to get back out after a bunch of heat cycles

 

[fordf150]

First, the generally accepted rule of thumb is to never "break-in" a saw (or any engine for that matter) on synthetic oil. its good to run dino-oil (conventional) for the first 3-4 gallons of fuel through the engine, which helps seat rings and mate the surfaces. Ive never heard of an engine burning up from running only synthetic from the beginning but its not great for it.

i dont buy that one.

broken in on Dolmar full synthetic oil at 40:1

 

[cus_deluxe]

looks like your gauge is broken.

 

[cus_deluxe]

and i said generally accepted. there are no hard and fast rules for break in, and these days with better engineering and whatnot, a lot of new cars come from the factory with synthetic oil. the only point i was trying to make in all this is that synthetic oil at 70:1 will not kill a chainsaw in 3 or 4 tanks, or 3 or 4 gallons of fuel. Buying top of the line oil and mixing it at the same ratio as wal-mart dino oil makes no sense to me. Thats part of the point of going and paying $12-14 a quart for the good stuff.

 

[7sleeper]

First, the generally accepted rule of thumb is to never "break-in" a saw (or any engine for that matter) on synthetic oil. its good to run dino-oil (conventional) for the first 3-4 gallons of fuel through the engine, which helps seat rings and mate the surfaces. Ive never heard of an engine burning up from running only synthetic from the beginning but its not great for it.

That is simply just plain not true! There is no "generally accepted rule..." and anyone trying to proclaim that is not living in reallity. I have never, and I have already been on this site for quite some time, seen any proof that one oil will break in better than any other! Modern machinery is already so good that modern engines hardly require any "special" break in any more. Just run them like you would any other saw.

What is much more important is correct carb settings! The oil, as long as it is for air cooled two stroke engines, is only a minor number in this equation! Correct carb settings and correct mixture are the major players!

Personally I use full synthetic with the top norms from a generic brand.

Why?

Because it costs less than Stihl orange bottle.

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