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Certified Technician
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Discussion Starter · #1 ·
Its about a 4-5 year old Echo EA-500 Auger, used commercially...

Complaint was that it wouldnt start and it had a failed clutch.

I just put a new piston and cylinder on his other one, same kind of failure but not quite so bad...

Given the nature of the equipment, can anyone explain why it failed? And no, it was not run lean (fixed main) and was only run on Ethanol Free fuel, and not straight gassed...











:trink39::thThumbsU
 

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Certified Technician
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Discussion Starter · #3 ·
Also, Echo uses a floating wrist pin...I had to made a custom puller to manually force the wrist pin out of the piston as it was seized in, notice the discoloration on the pin...
 

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Discussion Starter · #7 ·
No signs of loss of lubrication on the bearings, no scoring of the cylinder, or ring sticking beyond at the Exhaust port...
 

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Discussion Starter · #8 ·
Give yall a hint...

They run 3 of these things to plant/replant clear cutting sites...approx 18000 holes dug, about 6000 per machine, about 8-10" deep in close succession.
 

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Discussion Starter · #13 ·
Ill goahead and explain what killed it, Ill post it in WHITE font, so if you want to know, Highlight below to find out, if you dont want to know, dont highlite, or quote this post.

Being an auger, its not run at part throttle, they put it in the ground, wide open for 10-15 seconds at HIGH load...then lift it out of the hole @ idle, then drop it onto the ground 2 steps away, full throttle, full load....over and over. The engine never gets any time to lose the built up heat between holes. Your engine will always make heat...but when you run wide open, it makes the most heat, when you run it under high load, the cooling fan spins slower, and the engine heats up faster. The piston absorbs heat and cant get rid of it fast enough, and the hottest part of the piston, the area at the exhaust port...melts. To remedy this, they should either run it at wide open at all times, to allow it to blow off heat between holes, or let it idle longer between holes. Basically, long story short...they are overheating it. If you can imagine, if you went to a drag strip, took a 1/4 mile run...drove back around the track to the start again, made another run, over and over...the engine would be able to lose the heat that was soaked into it, between runs. However if you made 1/4 mile runs, turned around at the end of the track, and made a 1/4 mile run back, over and over..the engine would eventually overheat because you are adding heat faster than it can be lost. With air cooled engines, they are reliant on either engine speed (more air) or more time (at idle) to lose heat that soaks into the piston, crank, block, head...They are digging 6000 holes, probably 4 a minute...doesnt take long to overheat an engine. Im going to suggest that they do a 3 man rotation..for a little more time between holes, as well as a colder plug...
 

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Replying in white...

Interesting. Based on your description of how they were running it (lots of bursts of full throttle), I was going to guess that it got hot enough that thermal expansion got the better of them, and the aluminum piston expanded more than the (presumably) cast-iron sleeve, until the gap between the two was gone and the piston scored. But I wouldn't have guessed the piston would melt. Looks like their poor machines have led pretty hard lives!
 

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OMG I got another LawnBoy
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Looks like it got too hot.
 

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Also a different exhaust will cure the problem.
 

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I was thinking they bored the hole, and set it on the ground shut off while they placed the post, not letting it cool off normally with the flywheel fan blowing. Intermittent full-throttle opening, then shut off w/o cooling, leading to the heat load building w/o opportunity for it to be thrown off.
tom
 

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Old Iron Connoisseur
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I'm a long time Echo fan but much of their new EPA compliant machines are so lean, that even with synthetic oil, no ethanol, etc. they will score the piston. Fixed jet carbs do not allow enough fuel if ANY obstruction of the carb occurs which can be a stopped fuel filter in the tank. I'm going with too lean a fixed jet carb.
 
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