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Discussion Starter #1
Just a quick intro to a new project:

I bought a 27"/10HP Murray 627107X31A for cheap knowing it had a bad engine.



Pulling the recoil showed no resistance at all. Encouragingly, the auger and transmission seems to move the machine when pulled-over and the bails pulled, so that hardware looks at least promising.

I suspected a blown rod and negotiated the fellow down on that. The machine itself is in decent condition (built 2005); it'll need some tin work and some Rustoleum once I get the engine sorted.

It's an LH358SA. On disassembly, the rod had indeed broken and left a bit of shrapnel:



I'm guessing it ran low on oil; there's aluminium fused to the crankpin and some signs of bluing around the pin:




The piston looks relatively unscathed. There's no sign the skirts were involved and the crown looks like it may have just kissed the head:




The camshaft also seems undamaged:



I didn't see any sign the rod damaged the crankcase walls; no cracks, holes or even impact marks.

I think this one may be salvageable but it'll need a rod and crank at the minimum, plus a full gasket set etc.

I've been looking at re-power alternatives and am having some trouble finding a decent match; this is one of Tec's small-footprint, medium-frame jobs with a 1" shaft and extended snout. My plan is to try to cobble the bits together to fix this one before heading down the re-power road.

For now my little Rato-repowered compact Troy-bilt 2-stg will have to shoulder the driveway clearing duties while the Murray sits in dry-dock.



:)
 

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Discussion Starter #4
I'd wondered if the crank was a lost cause and just assumed it was: the bluing led be to believe that the crank pin surface had gotten red-hot and that the aluminium was hopelessly embedded in it.

I just watched a few YT videos showing this process. Pretty scary :) I'll use this as a backup plan if the crank I ordered is somehow NFG.

Thanks for the tip.
 

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I'm pretty sure the bluing on the rod journal is from the heat treating/hardening process at the factory. I've seen this on cranks that were in good condition as well. Plus if it had really gotten that hot there would likely have been evidence of oil coking around the area. At any rate, the muriatic acid should get rid of the aluminum deposits and the journal lightly polished with some fine grade emery cloth for good measure.

Sent from my SM-G960U using Tapatalk
 

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Discussion Starter #6
Quick update: I ended up buying a new rod and crank along with the parts needed to reassemble it, including new rings. Lapped the valves, set ring gaps and valve clearances and got her together in just a few hours. I wish I'd taken pictures of the assembly process. In the end, the machine fired up on the first pull. No smoke, no knocking. Sounds strong. Auger system sounds good; all 6 fwd and 2 rev speeds work well with good torque. Seems like solid machine.

I noticed that at full throttle it was running at a very high RPM (I didn't have my tach handy but judged by sound.) I suspect the governor linkage had self-adjusted over time (or was maladjusted by the PO trying to get further throw...) and that's what did the OE rod in. I'll set that using a tach a bit later. I need to get a few heat cycles into it and then get the tins back off to check the head bolt torque.

It's such a big machine for my small lot. I'm tempted to sell it on but would really love to try it a few times. It probably wouldn't garner a ton of interest in June anyway but might after the first decent snow of the winter of 2020/2021.

(I've got the acid and old crank and might still try to salvage it and sell it on but am in no rush...)
 

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and another one is saved, good job.

tx
 
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