Scored pistons

[TomKub]

Ok here it Goes. I have a Stihl 045 and 036 that both experienced piston and cylinder scoring on the exhaust port side. I used 93 octane (4gal) and (2) stihl 2 cycle mixes (orange ones). FS trimmer is fine 55 series blowers are fine and the ms210 as well. All have used the same fuel. I was cutting a 60” sugar maple so the saws were running hard for hours but I assumed that they were made for this type of workout. The 045 scoring inside the cylinder is minimal and can be honed. Piston rings are scored and will not release from the piston. 036 Piston has light scratching and cylinder as well however the rings are compressed into the piston similarly and will not expand from piston. What caused these failures?? No excess carbon buildup.

 

[cuinrearview]

How old is the fuel? How hot was it out? How often do you run the saws?

 

[a. palmer jr.]

Assuming you have no air leaks I would guess that the saw was overheated because you mentioned the stuck rings. When I did any all day cutting I would always bring more than one saw, kinda alternate them so they can cool down, especially in hot weather. Sometimes on those older saws it's not a bad idea to run them a little rich on the oil. I don't run 50:1 on anything..

 

[TomKub]

No air leaks. I will undoubtably run richer mix and richer carb adjustment. Fouled plug is cheaper than new top end. It’s just odd though that both saws seized within hours of each other. If I didn’t mix fuel and fill saw myself, I would believe that non mixed fuel was used. But that’s not the case. I was alternating after my first went down but to no prevail. Thanks for the thoughts

 

[cuinrearview]

No air leaks.

So you performed a vacuum and pressure test?

 

[TomKub]

How old is the fuel? How hot was it out? How often do you run the saws?

A few Weeks old. It was 80deg F. The 045 I’ll start a few times a year. The 034 I’ll cut some firewood 3-4 times during the year.

 

[cuinrearview]

My left hand gets pretty warm cutting in that kind of heat. It's really the common denominator here, provided you ran your other equipment from that can.

 

[HarleyT]

Lean seizure/overheating is the result, the causes are many.

Again, I say many.
The 045 and 036 are old, and Stihls can run seemingly fine for a long time with piston damage, so you will not find a "one time" cause for your troubles, as you are looking for.

 

[northwest saws]

Ok here it Goes. I have a Stihl 045 and 036 that both experienced piston and cylinder scoring on the exhaust port side. I used 93 octane (4gal) and (2) stihl 2 cycle mixes (orange ones). FS trimmer is fine 55 series blowers are fine and the ms210 as well. All have used the same fuel. I was cutting a 60” sugar maple so the saws were running hard for hours but I assumed that they were made for this type of workout. The 045 scoring inside the cylinder is minimal and can be honed. Piston rings are scored and will not release from the piston. 036 Piston has light scratching and cylinder as well however the rings are compressed into the piston similarly and will not expand from piston. What caused these failures?? No excess carbon buildup.

The fact that you mentioned they both seized hours apart makes me strongly think bad mix/poor lubrication. Do I understand correctly you mixed two 2.6 ounce orange bottles of 2 cycle mix in 4 gallons of 93 octane gas?


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[HarleyT]

Yes, that was it!!!

 

[cuinrearview]

Oh!

 

[HarleyT]

OOOOOoooo....

 

[SEAM]

100:1 mix with a 50:1 oil will kill any engine on a hot day... better also check the ones still running.

 

[HarleyT]

No, folks will tell you almost anything, and a lot of a-holes here will believe anything.
But in reality, the "bad fuel mix" thingy, is just plain silly. Unless someone followed the 100:1 or so bullchit....

 

[tomdcoker]

I do not mix more than 2 gal. at a time. I had a customer a couple years back that brought me 3 or 4 saws to fix and all of them were scored. One was an 028 that I sold him a couple months back. I asked him how many he had burnt up and he told me 6 in the last year. He was using them to cut firewood from wood an arborist brought him. I questioned him a bought his use of the saws and the only reason we could come to was because he mixed his fuel up 5 gal. at a time. Tom

 

[TomKub]

The fact that you mentioned they both seized hours apart makes me strongly think bad mix/poor lubrication. Do I understand correctly you mixed two 2.6 ounce orange bottles of 2 cycle mix in 4 gallons of 93 octane gas?


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Yes each oil bottle does 2 gal of gas

 

[Canyon Angler]

I only mix a gallon at a time. Three ounces of oil in a gallon of gas. Works out to about 42-to-1.

Two 2.6 ounce bottles of oil in four gallons of gas is a mix of 98-to-1.

 

[TomKub]

I only mix a gallon at a time. Three ounces of oil in a gallon of gas. Works out to about 42-to-1.

Two 2.6 ounce bottles of oil in four gallons of gas is a mix of 98-to-1.

The 2.6 oil I have states that it makes 2 gal

 

[Huskybill]

I only use the pre mix in cans now. The 50:1 mix with the standard gas. This will last for three years they say. When I was mixing 2t oil I left my saws filled for six months from spring to fall cutting season(winter). I never had a problem with the saws. I never left gas/mix in the five gallon cans. I used the left over 2t mix in my splitters.

I don’t use ethonal because the pre mix only lasts for 30 days.

 

[northwest saws]

The 2.6 oil I have states that it makes 2 gal

I’m not sure where you got that mix but Mr angler is correct, you’re using a mix ratio close to 100:1. One 2.6 ounce bottle is good for only 1 gallon of gas to make 50:1 mix ratio. I’m afraid that mix right there is your prime cause as to why you have two seized saws. I would definitely purge your other pieces of equipment that filled with that mix. Sorry about the bit of misfortune, things happen now and again. Hope you can get em fixed. FYI do not hone out either of those cylinders, that will trash em. [emoji111]️


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