I picked up a scored 064 this past fall for pretty cheap. It's had a troubled history and actually scored two pistons before the owner traded it into the shop. Whoever replaced the original p/c must not have cleaned it up before hand, because I found this today:
I doubt this happened recently as you can see the difference in coloration on the metal on either side of the crack. I'm just wondering a few things: 1. Is this the cause of the air leak? I doubt the seals were replaced after the first rebuild, so those were my main suspects. It came to me partially disassembled so no pressure test. It doesn't seem to be into the crankcase, but there's a section that may be causing a leak at the cylinder gasket once the saw is being leaned on in a cut. 2. Is it worth rebuilding with another set of cases or case half?
There's a flywheel side crankcase half on eBay right now for $40+shipping. I'd sure be tempted to snag it, get some bearings and seals, and put it together. Welding would be prohibitively expensive, so it's that or part it out.
Hmm... I saw that one before this whole mess. I may end up going that route. It's a shame, the bearings seem great on this one.
I cant see the crack extending into the crankcase itself, but i dont know for sure. I imagine the crack could get worse... And take out a freshly rebuilt saw.
Do you plan to keep it or sell it? Even if the crack didn't immediately cause problems, I'd expect it to have a significant effect on the saw's value. What do the plastics, handles, recoil, etc. look like? Will it be pretty enough to justify a full rebuild? I wonder whether you couldn't just tap the dowel pins out and then disassemble the case by heating it in an oven, so as to avoid the stress that splitting the case the usual way puts on the bearings?
I plan to keep it... the plastics are rough but everything is there for a rebuild. I like your suggestion on the "gentle" way of splitting the case. I was already wondering if my husky case splitter can fit over the crank. It was close on the 460.
Well, if you plan to keep it and aren't worried about the crack structurally, you could always improvise a base gasket and mount the cylinder temporarily to facilitate pressure/vac testing. You might find that some part of that crack does extend into the crank area, or you might instead find a bad crank seal that explains the scoring.
Putting mild axial pressure on a ball bearing with a press type tool does far less damage then tapping the case halves apart with a soft hammer.
Well, I pulled the trigger on the case half, new bearings, and another gasket set that included an AM case gasket. I'm going to risk the After Market gasket this time (went with OEM on the last one I did). My plan is to sand the halves on a piece of glass and make sure they match up well enough.
Since you have the cylinder off and the seals etc still in the crankcase. Try this redneck method of mine. Put paper bag or something else underneath. Fill the crankcase with mix. Walk away and come back in a bit and see where and IF you have any leaks at cracks or seal areas.
TIG welding , or new case if you know someone with TIG use magnesium welding rods and you ready to go. some examples
