Small Engine Death!

Hello,

It WAS a 31CC blower. These little things never dye a slow death! They come to a quick demise,


Guido.

Nice photo backdrop fro such ugly. It looks like it ate sand. Jim

I know that feeling Guido. My rototiller died with a bang a couple of weeks ago. Here's part of the connecting rod I found inside.

Hello TomH in PA,

That is not pretty! Some one killed that blower, not me! Oil seems a requirement for a two stroke or else,

Guido.

That 2 cycle oil comes in handy sometimes, especially in a 2 cycle engine.

I have a Stihl chain saw so I buy the little silver bottles of syn. which treats a gallon of gas at 50:1. I was putting new rings in a couple of string trimmers the other day read in the manual....finally read it after half a dozen years....said 40:1. After the overhauls, I had different things go out on both trimmers and the Stihl is getting hard to crank so I just sait PFFFFFFt and bought a new ez start chain saw and a light weight easy start, long shaft, for us tall guys Stihl PF 50 C-E trimmer which is also an easy start. Decided to up the oil to 1 ? - 2.7 oz bottles per gallon and see if the rings don't last a little longer. Nice thing about the syn. it doesn't smoke. We'll see.

Hello Texasmark1,

More oil in the mix is not the answer, as you already found out, 40 instead of 50 to 1! Doing so will have the same effects as too little oil. Now you are doing if again? If you had used the proper mix, your engine would STIHL be purring, pardon the pun! By adding more oil to the mix,you are lowering the required octane ratings that the engine requires. The engine may or may not smoke. But the issue is that you are LOWERING the octane ratings. That results in poor and cold combustion, which leads to early failure because of it. The owners manual should be your bible. Proper maintenace, quality gas and oil plus proper intented use of the product are the key to long equipment life.90% or more of the people that I ask, do not have the unit's manual say no..... chucked it! It never seems to amaze me!!!

Guido.

A friend had his kids earning pocket money by mowing lawns around town. Good experience and taught the kids the value of work. All went well until the kids ran the 2 cycle lawn boy push mower out of gas. An old fellow at the housing project they were mowing offered to give them a little gas from a can he had . Problem was , his gas was not a 2 cycle mix, 100% gas. Nobody happy that night.

When I worked at a farm equipment shop I did the Lawnboy work and the most problems were plugged exhaust ports from leaking air filter, dirty air filter causing engine to run rich causing more carbon, or too much oil, same problem. Air filter and proper mix would insure a proper running Lawnboy that would last a long time, great machine but too costly for me

Pheeew, that aint ugly, that is UGLY!!
Emissions laws have caused the manufacturers to run them right on the border line of burning up from lean settings. Then add some old fuel and a bit of ethanol junk in the jetting. Every spring I get a pile of blowers, weed whackers, saws etc because they run them with last years fuel, wonder how many millions get spent on new equipment each spring for being too cheap to throw out $2 worth of stale fuel?? LOL

Hello Butch(OH),


I have reached a point now that nothing surprises me anymore. Its getting harder to repeat the same thing.!
Buyng a throw away machine, and expect to run a life time, and.....using the mix THEY think is best. NOT!!!!

Guido.

(quoted from post at 23:18:45 04/24/17) Hello Texasmark1,

More oil in the mix is not the answer, as you already found out, 40 instead of 50 to 1! Doing so will have the same effects as too little oil. Now you are doing if again? If you had used the proper mix, your engine would STIHL be purring, pardon the pun! By adding more oil to the mix,you are lowering the required octane ratings that the engine requires. The engine may or may not smoke. But the issue is that you are LOWERING the octane ratings. That results in poor and cold combustion, which leads to early failure because of it. The owners manual should be your bible. Proper maintenace, quality gas and oil plus proper intented use of the product are the key to long equipment life.90% or more of the people that I ask, do not have the unit's manual say no..... chucked it! It never seems to amaze me!!!

Guido.

Click to expand...

Sorry guy, but that's not how it works. Octane isn't the killer in 2 strokes. Crappy mix oil, poor/dirty fuel, overly rich or lean settings, filthy or no air cleaner, cracked or leaking intake boots/blocks, carbon in the cylinder...that's what kills them. A slightly rich mix of 40-1 instead of 50-1 is not going to lead to premature 2 cycle death. That pic of the piston in your OP shows a really rich mix and carbon build up. I'm betting the air cleaner was clogged too, even if it "looked" clean. Combine any of that with a leaky seal or boot and you get failures just like the ones pictured.

Hi Guido,

"More oil in the mix is not the answer, as you already found out, 40 instead of 50 to 1!" Would you clarify that please? I was using 50 syn and the manual said to use 40:1 didn't specify dino nor syn. It also said 89 octane gas.

Since Stihl sells syn plus storage additives in their private label engine oil, then there must be a reason. I don't see the problem with running 2.7x1.5 = 4 oz of oil to 127 oz of fuel vs 2.7 oz. That's a change of 4/2.7= 50% but an octane change of 87-89 would be 89/87= 2% if I went with the recommended 89 octane fuel. But I didn't see that as a need either....see comments below. I use 87 in everything around here including my 90 hp 2 stroke OB which doesn't care if I use 87 or the recommended 89 and it's stated (serv. man.) min compression is 120 psi.

Octane increase prevents preignition, detonation of the fuel air mix prior to the spark origination causing piston top damage, probably skirt slapping damage, cylinder wall scoring below the ring groove (2 stroker) which shouldn't matter.....remembering the 10.5 compression engines back in the 60's power race between auto OEMs requiring 95 [I think it was then...R rated or M rated, not (R+M)/2 as it is today]. I read that preignition burns holes in the top of pistons. Had no such deformation nor visual indication of any piston pitting in the crown.

The chain saw spec in the manual on compression min is 90 psi so I suppose the string trimmer would be about the same. Considering 14.7 psi atmosphere that's only a 6:1 compression ratio. The 10.5:1 of old days would be up in the 150+ psi reading.

So I don't follow you on more oil lowering the octane to the point where you would have preignition. What's that got to do with ring/cylinder wall wear. Would think just the opposite....take it to the limit....what would happen if no oil were used? I know. I helped to overhaul a neighbor's 1949 Mercury 110 hp flat head V8 when I was a kid and we put it together dry.......obvious results.

Going to stop here and wait for you to come back. I'm interested in what you have to say and supporting evidence. I don't have a heavy background in small engines, or any for that matter. A few exceptions, like getting 4 kids through "rent-a-wrecks" and a few tractor restorations, but mostly just keeping all my stuff running, which usually didn't take much effort, over the years which was quite a bit but not like doing it commercially.

I keep all my machines in good working order and strongly believe in "snake oil" additives which have proven themselves to me time and time again. Sea Foam is my snake oil for non-diesels and Power Services is what I use with them. The items you mentioned were checked and only required normal maintenance cleaning. The problem as I see it is in the construction of the machine......cast iron ring running against an aluminum cast cylinder, like the problems all small engines had before cast iron cylinder liners were used on aluminum engines. I do remember that well. Thanks for contributing.

Funny that the ladies got it right when refueling the Maytag motors on their washing machines. I come across a lot of motors still running that weren't rebuilt.

You got that BACKWARDS, Guido.

Higher octane gasoline is HARDER to ignite.

High octane gas has slightly less heat energy in it (less BTU's).

On the other hand, with diesel fuel CETANE numbers work the other was HIGHER cetane = easier to ignite.

Octane Facts
• Knock occurs when cylinder pressures are high. It is normal for an engine to ping a little at full throttle
because cylinder pressures are very high at full throttle. Engine knock, however, should not be ignored
since it can result in serious damage to the engine.

• High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when
cylinder pressures are high.

• If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in
switching to higher octane gasoline.

• If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could
be a problem with the engine’s electronic control systems, ignition timing or exhaust gas recirculation. On a
high mileage engine, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.

• Almost all of today’s new cars have fuel-injected engines that need to use gasoline with a detergent additive.
They do not necessarily need high octane gasoline with a detergent additive. Generally, new automobiles
need high octane gasoline only if the manufacturer recommends it.

• Always follow the auto manufacturer’s octane recommendations in your owner’s manual.


Octane Myths

• High octane gasoline improves mileage.
In general, if your car is designed to run on 87 octane gasoline, high octane gasoline will not improve
mileage. If switching to high octane gasoline does improve mileage, you might find that your engine, or its
control systems, need repair.

• High octane gasoline gives quicker starting.
No, it doesn’t.

• High octane gasoline increases power.
If your car is designed to run on 87 octane gasoline, you shouldn’t notice any more power on high octane
gasoline. Again, if it does make a noticeable difference, your engine, or the engine’s electronic control
systems, may need repair.

• High octane gasoline has been refined more – it is just a better product.
Additional refining steps are used to increase the octane; however, these additional steps do not necessarily
make the gasoline a “better” product for all engines. They just yield a different blend of hydrocarbons that
burn more slowly. The additional steps also increase the price.

I'm not Guido, but I agree, extra oil is not the answer.

Not sure about the octane theory, but extra oil does lean the mix. The oil is basically inert, so the main jet doesn't know the difference, it still lets the same amount of liquid through, but the ratio of usable gasoline is reduced, therefore leaning the mixture. Not a real concern with adjustable jetted carbs, as long as it is readjusted, but for fixed jet carbs, it can make enough difference to lean one out to the point of detonation, especially on a marine engine that can pull heavy loads for extended time.

Another problem with extra oil is the carbon build up, especially on the exhaust side of the piston/cylinder wall. This can be enough to decrease piston to bore clearance, and pack into the ring lands.

I've seen this to be more prevalent on marine engines, often occurs when the onboard tank is continually topped up with fuel, extra oil is added, guessing at the amount, go ahead and dump the rest in instead of wasting it... Then add in the evaporation factor.

It is amazing how stingy with oil the oil injected engines are! They start out at 200:1 at idle, only get 50:1 at full throttle.

Steve, I can absolutely 100% guarantee you that the average 2 stroke L+G equipment out in America stands a far, far, far better chance of the air/fuel mix being rich due to poor air cleaner upkeep than the difference between 40-1 and 50-1 oil mixes. Considering very few people actually go to the trouble of adding ALL the oil in their little 2.7 oz bottle to mix by rinsing the bottle with fuel and adding it to the mix, or by precisely measuring the amount to be added from a larger jug, I think worrying over the minor extra amount of "leaning" from a 40-1 vs 50-1 mix is wasted time. And for that matter, I believe you are confusing terms here. A "lean mix" is one with more gas and less oil. A carb "running lean" means less fuel mix and more air. Adding extra oil, which DOES BURN btw, to the mix results in a "richer" mix, not a leaner mix. True, the jet doesn't know the difference, but less fuel and more oil doesn't equate to a "lean" mix or "lean" carb condition. Now, that being said, 30ish years back the head engine tech at the largest east coast Jonsered wholesaler told us that a really rich mix (we're talking 16-1, 20-1, something like what was used in the early 60's) could cause bearing failure due to build up on the crank bearings on saws designed to run at 14K rpm using 50-1 fuel mixes. He would elaborate when asked for further info, but that was his theory. I'm sure there is a point of diminishing return, but arguing over a 40-1 vs 50-1 mix is near pointless in real world terms. After all, how many people add EXACTLY 1 measured gallon of gas to the can? If you go over a little, you "lean" the mix by that much. If you go under, it's that much richer. If the gas has alcohol in it to prevent water issues or you're buying ethanol fuels, the mix is also going to be that much more or less rich or lean. How many people agitate the mix every single time to be sure it's all thoroughly mixed? How many people put the oil int he can and add the gas vs add the gas then put in the oil?

The point is that the variables can add up to the point of making the argument purely academic with no real world application. Stick with what you like, keep things well maintained and clean and don't lean the carb out!

Hello Texasmark1,

I missed the 89 octane, but more oil by volume will have a lower octane mix. I did not state any knocking as a result though. Colder combustion results in carbon collection and exhaust clogging. Engine wear soon follows. Maintaining your equipment as you do, it is a plus.
Guido.

Usual sequence for that is the fuel mixture goes lean; dirt partially blocking a jet will do it. Any air leak from a gasket failure or bolts loosening will also do it.

That causes the engine piston and chamber to overheat once the engine starts detonating; this is because normal combustion is like a grass fire moving thru the air/fuel mix. It burns, does not explode.

Detonating is when about half the fuel charge is burned, the flame front cooks the 'end gases' in the unburnt portion, and those gases explode. You hear that as 'pinging' when the engine detonates. Higher octane fuel is solely made to not explode when it's end gasses are heated. It's the only thing it does.

The explosion shock wave blows a boundary layer of air/fuel molecules off the surface of the piston and the exposed surfaces of the head and cylinder. The boundary layer insulated the parts from the heat of combustion, when it's gone the metal in the piston dome is the first to overheat.

The piston expands and becomes a near press fit in the cylinder, it also traps the rings in their grooves so they no long seal the combustion pressure and that leaks down the piston.

All of this is cooking the oil film off the cylinder wall and piston, so the piston skirt starts to smear off onto the cylinder. That's what all the vertical streaks are.

Detonation is so destructive that just 5 or 10 pings and you'll start seeing damage; let it go on for a couple of thousand and the engine dies.

Preignition is a little different. Something in the combustion chamber is glowing hot; bit of carbon, ground electrode of the plugs, whatever it is, it's hot enough the start the fuel burning.

So the fuel starts burning early, well before the spark plug can light it off. Not related to octane, get rid of the hot spot, you get rid of the preignition. Lean mixture probably makes it more likely, since lean burns hotter....

OK. here is a big question. How exactly does one "throw out" that left over fuel? At least around here, there is no easy or simple way to get rid of unwanted fuel. I can't legally pour it down the drain - eith4er inside or outside the house. I can't pour it on the ground. It would appear that one would have to collect it in a container and take it to a hazmat disposal facility. Not a good thing to add to today's sensitive fuel injected cars to burn off that way.

Thanks for the reply.

Sea Foam is an anticarbon treatment that was always part of my marine engine fuel mix. Use it around the farm on other engines from time to time or as a fuel storage aid if not using something else.


On an inboard marine engine like the ones you see sitting for years at a time in marinas around the world, no telling what's going on in those engines considering todays fuel and the time they spend just sitting and sitting and sitting and when they do get used, it's half an hour of no wake to get to open water then put her on cruise speed for a couple of hours then back to the half hour to the dock then secure her to sit for more months at a time.

Also on 2 strokes, the oil in the mix helps to reduce any piston scuffing and being in the fuel gets on the crank, rods, bearings and piston skirt on the intake half stroke and on the crown on both strokes. On ratio, my 2002 Merc 90 VRO system was 80:1 at idle to 50:1 at WOT, obviously due to the lower stresses and temps.

Some interesting octane and compression temp conversations here: BOB IS THE OIL GUY ? Forums ? Lubrication and General Automotive ? Mechanical/Maintenance Forum ? Octane and Combustion Temperature.

I don't think anything was gleaned out of this attempted opportunity, for me anyway. Oh well, the old stuff is out and the easy cranking new stuff is in. Hoorah!

Hmm...... JB Weld?

Hmm,

This thread has long comments with lots of words and information.

I'll stick with putting the cows on the yard since they self-start and dont ask for any oil at all!

I would have to wonder about anyone who would toss fuel down a drain, legal or not, or throw it on the ground. Local hazmat days are good for getting rid of all sorts of junk I use them myself but not for old fuel. It is best to not generate stale fuel to begin with by controlling how much you keep around. Myself I dont generate any at all. We mix one gallon at a time and use it year around in various equipment. On the rare occasion we get some "iffy" fuel mix we toss it in one of the tractors or other 4 stroke equipment because there is very little of it mixed in a large fuel tank. Now and then we have the really rotten disgusting stuff from equipment that gets brought here for repair. If its a tractor with 20 gallons in the tank it goes home with the owner. Smaller quantities go in a hog pan and it is burned. I save a bit for starting brush fires.

(quoted from post at 16:47:01 04/25/17) OK. here is a big question. How exactly does one "throw out" that left over fuel? At least around here, there is no easy or simple way to get rid of unwanted fuel. I can't legally pour it down the drain - eith4er inside or outside the house. I can't pour it on the ground. It would appear that one would have to collect it in a container and take it to a hazmat disposal facility. Not a good thing to add to today's sensitive fuel injected cars to burn off that way.

Click to expand...

Really? Antique tractors, like the ones this site is dedicated to, run great on old "stale" 2 stroke mix fuels. That's where all my "old" fuel goes. It works fine.

Hello Bret4207,

Me too. I put in in my mowers, 4cycle weed wacker, and log splitter. A little oil in the gas is no problem
on 4stoke/cycle engines,

Guido.

Took me awhile to get my head around this, but a 40 to 1 mix actually results in a LEANER condition than a 50 to 1 mix. A 50 to 1 mix has MORE gasoline in it than the 40 to 1 mix. Adding more oil to the mix could actually lead to higher operating temperatures because of being leaner. I've had some experience with 2 stroke dirt bikes.

Look, regardless of how you want to make things appear, in the real world if you tell someone you are running a "lean" 2 cycle mix it always, always, always means more gas, less oil. Yes, 40-1 has less gas in a given amount than 50-1, but that's not a
"leaner" mix. And a "lean condition", meaning the engine has less fuel mix than it needs, is the result of the amount of air vs fuel entering the engine.

I don't know who came up with the notion of 40-1 somehow being
"leaner" than 50-1, but all you're doing is confusing the issue of rich/lean mixes and rich/lean engine conditions. Trust me, I "wrapped my head around this" a long time ago, and the differences involved are far outweighed by other more factors and variations.

Problem is the terminology. When someone refers to a lean or rich mix, I assume fuel/air, not gas/oil. Yes, 40:1 is a richer oil/fuel ratio as in there is more oil than in a 50:1 mix but does that translate into a leaner fuel/air mixture? Obviously the mix oil does partially burn, otherwise we wouldn't get smoke so really it's not "inert" as someone stated earlier.
It's this kind of misinformation, or well intentioned advise which confuses the issue. When in doubt, do what the manufacturer intended with regard to mixing fuel and keep things tuned up.

The biggest problem I've seen is with oxygenated (gas with ethanol) fuel and mix oil. It seems to cause a more sticky, destructive mess once all the vapor has evaporated out of the gas. This causes passages, jets, you name it, inside the carburetor to become smaller, thus leading to the lean air/fuel mixture which causes damage to small 2 strokes. Not to mention what it does to fuel lines in a very small amount of time!

If someone refers to a rich or lean "mix", that has to be fuel. If someone says an engine is "running" lean or rich, that's air/fuel mix. I've been running, selling and wrenching on 2 strokes for 40 years and I've never, ever heard some of the stuff I'm hearing here. I don't know where this came from, but if people are confusing terminology this much, it's no wonder they have so many issues with 2 strokes.