Burnham
Woods walker
Acid reflux 
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Al Smith
Mac Daddy
I guess I've never seen an actual detonation .I have seen melt downs early on in small block Chevys though .Of course the scalded piston on saws from a lean run and the usual grenaded piston from a snag or a chunk of something the saw ate which didn't agree with it's digestive sytem in a manner of speaking .
I'll tell you what I did see one time I'd have never believed .A damned tractor spit a circlic ,ran the wrist pin into the cylinder liner and tossed the clip on top of the piston and buried it in the piston top and never missed a beat .How in the world it ever got there past the piston skirt remains a great mystery .
I'll tell you what I did see one time I'd have never believed .A damned tractor spit a circlic ,ran the wrist pin into the cylinder liner and tossed the clip on top of the piston and buried it in the piston top and never missed a beat .How in the world it ever got there past the piston skirt remains a great mystery .
CurSedVoyce
California Hillbilly
M
MCW
Guest
I agree TW that it is detonation and piston crown overheating that caused the damage. I have seen this on motor vehicle pistons before (unfortunately my own) where I advanced the timing too far and didn't hear the "pinging" sound over the intake/exhaust noise. Piston crown overheats, not enough to sieze, and the crown gradually erodes from the high velocity overheated flame front after ignition. I'd say the damage on this piston was slow and happened over quite some time. The difference in an overhead valve 4 stroke is that this damage occurs across the whole top of the piston as one of the previous pics here showed.
The original picture indicated more piston erosion to me, not physical damage from a foreign object. Same deal as the rocks you showed but is also quite common in high pressure irrigation pumps with alloy housings.
The original picture indicated more piston erosion to me, not physical damage from a foreign object. Same deal as the rocks you showed but is also quite common in high pressure irrigation pumps with alloy housings.
Magnus
TreeHouser
Here is one I got in today.
This is first daylight for this piston in 18 years.
This is first daylight for this piston in 18 years.
Al Smith
Mac Daddy
Get out the sandpaper Magnus . With a little work you can save it .
Magnus
TreeHouser
Nope. This will go to the shelf. .
I have been looking for a 42 Special for a long time to keep in collection.
The thing that keep the bearing ball in place came out...
I could replace bearings, seals, fix up piston and have let it go, but I rather keep it if I can.
I have been looking for a 42 Special for a long time to keep in collection.
The thing that keep the bearing ball in place came out...
I could replace bearings, seals, fix up piston and have let it go, but I rather keep it if I can.
Cut4fun
Redneck Chainsaw Repair
- Joined
- Nov 27, 2007
- Messages
- 2,635
Oregon roller nose bar in 026-066 stihl mount I put on the little 026 pro I took in trade. I just wanted to test with 325-7 325-8 and 3/8-7 without having to swap bars. I know, lazy and just really wanted the bar and thats how I sold myself to buy it 
Was using some 325 rm2 was the only problem on the chain side for the 325. Need to find my 325 rs loops.
Just a crappy cell pic while in barn.
Was using some 325 rm2 was the only problem on the chain side for the 325. Need to find my 325 rs loops.
Just a crappy cell pic while in barn.
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