Sears two cycle leaf blower piston ring

[trader_4]

OK, so here we go again. Last Fall I had trouble with this Sears two cycle leaf blower, where it would not start. Finally figured out it was a stuck piston ring. The ring broke when I tried to get it out, so I cleaned up the groove with a tiny screwdriver, got all the carbon out, got a new ring, put it in. In floated freely. Put it back together and it ran fine for awhile, then I had carb troubles. So, I bought a new carb from China and it ran better than when it was new. I put maybe 8 hours of use on it last Fall. Now it won't start again, won't fire.

After exhausting all possibilities, I took it apart again and the piston ring is stuck again. Sides of the piston have some black, shellac like stuff on it too. Broke the ring again, but have it all cleaned up again. The question is why did it foul again? Some more history, when this was new ten years ago, I should have taken it back, because it didn't run well with no choke. So most of the time on it, I ran it with half choke. Of course if they had screws you could adjust, I could have tuned it, but instead I just put up with it. So, first time the ring got stuck, I figured it was probably from running it too rich all those years. After putting the new ring in, I probably ran it for a few hours with the old carb and half choke. But after that I put the new carb on and it ran beautifully, no choke. I made sure to use a modern synthetic oil, mixed to the correct ratio. So, how did it get fouled again in just

8 hours? I know I should just put it out into the dump, but it's otherwise in fine shape and runs great when it runs and this has become kind of a battle of wills.

[hubops]

Just a wild-ass guess - maybe the original stuck ring caused some deformation/wear in the cylinder wall that caused the new ring to stick ? John T.

[Clare Snyder]

Not likely. Are you mixing the synthetic oil to the engine spec or the oil spec? Are you using ethanol free gas? I'd throw in a new ring, mix ethanol free gas with the synthetic oil (not marine, right?) to the oil manufacturer's sprc - i.e. 50:1 even if the engine says 16:1 - and add some "sea foam" to the mix according to the instructions on the can. If you are using marine or water-cooled snowmobile oil that could be your problem - weedeaters run a lot hotter than water cooled marine engines. The cyl walls won't cause the ring to stick in the piston.

[hubops]

"Weed Eater warns against using automotive or boat engine oil, since it is not properly formulated and can damage the engine."

John T.

[Clare Snyder]

Like I said - do NOT use outboard motor oil - - - -

[trader_4]

It was to the engine spec, or close to it. 40:1 I have that and a lawn edger, one might be 40, the other 45, I know if one is different, I just split the difference. I can check tomorrow and see what the oil says.

No, I don't even know where to find it around here. I guess I could buy the super expensive stuff at HD, but then if it's ethanol related, why did it work for 10+ years, but now foul the ring, then foul it again in only 8 hours? Also, in the fall, when I was having trouble, I did mix up fresh gas and used it within a month or two. So it's not like it had old gas that then ran through it causing the problems. It was fresh gas that caused the trouble. I think I recall it getting harder to start the last couple times in Dec, then would not start at all just now.

But in general, usually, the gas does sit around. You know how it goes. I have a one gallon plastic jug, the little oil things come in a size that makes a gallon. But after the fall, whatever is left, sits there. I guess I could throw it out. But funny thing here, I took the carb apart and it was spotless, no sign of anything fouling.

I'd throw in a new ring,

No, it's regular synthetic, not marine.

to

Thanks.

[Xeno]

In the US, the fuel is, for want of a better word, crap. You cannot

*leave it* in the machine and you need to properly *winterise* any and all petrol powered equipment. EG.

The shellac like appearance is from the breakdown of the fuel that is remaining in the cylinders. It is normal to run the devices out of fuel but with two stroke engines that's a fraught practice. In that case you need to use a *fuel stabilizer*.

Two points about ethanol laced fuel; 1, it does not store well and will rapidly break down with the ethanol separating out and forming a nasty smelling brown gunk which clogs carburettors and forms varnish like coatings on everything. Hence the need for a fuel stabilizer additive.

2, the ethanol is *hygroscopic* which means it will absorb atmospheric moisture and become very corrosive.

[trader_4]

That's an interesting theory, that the shellac like stuff isn't from combustion of the fuel, but from whatever is left that later dries up and hardens. But it doesn't really explain how a new ring failed in so few hours, while the previous one lasted ten years, with no change in how I've used it. Also, after fixing it last fall, I used it every couple weeks, for a total of maybe 8 hours and I recall that near the end, it was getting harder to start, so I suspect the ring was already fouled. In which case, if it's fuel left in the cylinder, then it must be happening after it's shut off each time and left for a week or two.

I have stabilizer and usually add it to the last tank of gas that I use for the mower, which I also use to make the gas for the two cycles. Can't say for sure that I did it this winter though. I suppose it's a good idea to just put some in each time I refill it. On the other hand, the Sears mower, also ten plus years old, with gas left in it over winter, never a problem, starts right up. Then I have a Sears snowblower with a Tecumseh engine, and that has fouled from gas, I've has that carb off, cleaned it several times. This is so hard to understand. Some carbs seem very vulnerable, others immune. And with the blower, it ran for ten years, fine. I suppose something else could be going on, maybe now that it's old it doesn't burn as clean. But I was thinking the opposite. Like I said, when I bought it, I should have returned it. It seemed it would not run as well with choke off as with half choke. With half choke, it would instantly pick up speed. So, I ran it that way for ten years. Of course if those hippie environmentalists didn't make the carb screws so you can't adjust them with a screwdriver, I would have just made it run right ten years ago. Meanwhile, I hope they are happy, all the whales I've killed running it rich all those years.

When that ring fouled and stuck last fall, I figured it was carbon and likely from it running too rich all those years. I thought with the new ring, I was good to go. Shortly after, I had problems with the carb and bought a new one from China. With that, she fired right up and ran perfectly, no choke, better than ever. So then I thought for sure I was good to go for a long time. Yet is seems that it had trouble starting at the end of last fall. IDK, very frustrating. I suppose I should go buy a new one, but not sure they don't have trouble too.

Thanks for the tips. I will start adding stabilizer to the fuel, even during periods when eqpt is being used, because a two gallon can lasts me many months even then. I wonder if it's a good idea to pull the plug on the blower and squirt some fogging oil or similar in at the end of the season? If the ring is getting stuck from leftover crap in there, that should help, can't hurt.

[Rod Speed]

Maybe the second one was just a dud ring.

Maybe that one has a piston which doesn’t see a fouled ring so easily.

Likely just a better design, designed to not foul so easily.

Yeah, those small engines are a pain in the arse.

[trader_4]

What is a dud ring? It's just spring steel. The problem isn't the ring, it's that carbon and gunk fills up the groove so the ring sticks, it binds up in the piston groove.

[Rod Speed]

One that isnt made properly so its too easy to gunk up and jam in the slot in the piston.

Duh, but if the ring isnt finished properly it can gunk up enough to jam in the groove.

[trader_4]

It fit, it floated freely in the groove.

Yeah, sure, whatever.

[Xeno]

Sorry, I didn't realise Sea Foam (the company) had a fuel stabiliser product. I was only aware of the Sea Foam spray that is used to clean out intake systems on GDI engines.

[Rod Speed]

But may well have had less free space around it in the groove or have had a worse finish so it gummed up much quicker than the original one did. Clearly there has to be a reason it seized up much quicker and you claimed that it wasn’t what fuel etc was used or how the engine was used.

You never could bullshit your way out of a wet paper bag.

[trader_4]

I didn't claim that it wasn't the fuel, I only said that the fuel that went in was relatively new, but it was ethanol and it could have been around for a couple months. What I did say was that fuel like that or that had been around longer went into it for ten plus years with no problems until last year. And it's not just the ring, the sides of the piston had the shellac type brown stuff on it too.

[Rod Speed]

That’s what I said you said.

Sure, but its less clear that that stops it working fine.

[trader_4]

Update. Piston ring arrived, it's back together and running A-OK again. IDK what to do at this point. I suppose I should go buy some of that expensive non-ethanol gas at HD. But I still have

3/4 gallon of mixed, pour it out on the ground? Decisions, decisions...

[Xeno]

Given what the crappy fuel has already cost you, it's an easy decision - ditch it.