340 shedding piston material

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iScamp

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So, my brother's 340 wasn't quite running right. The engine was running at low rpm and he heard this tinkling sound traveling down the header pipes. We decided to borescope the engine.

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Looks like that top ring butted together and took the top of the ring land out.
 
iScamp said:
JC Whitney used to sell Overhaul Pellets. Maybe find some of those. :D
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Hello iScamp:
As I remember they were little pellet's (looked like rabbit poop) and came in a quart like oil can and a blister pack thingy...
Simply drop one or two down the spark plug hole and your worriers were gone for a week or two...
Worked wonders when selling a car that needed a ring job.....
Happy Mopar :)
Arron.
 
I'd get it out of there before it "sheds" the rest of the piston in one lump sum.
 
cudamark said:
Maybe running too lean? Detonation?
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According information gathered on this forum (thanks, FABO!), the engine overheated and that caused the piston ring to butt together. The ring had nowhere to go but, up. That area of piston at the valve relief being the weakest part.
 
Arron tate said:
Hello iScamp:
As I remember they were little pellet's (looked like rabbit poop) and came in a quart like oil can and a blister pack thingy...
Simply drop one or two down the spark plug hole and your worriers were gone for a week or two...
Worked wonders when selling a car that needed a ring job.....
Happy Mopar :)
Arron.
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I wish I had a dozen of those cans to display on a shelf.
 
Scope some other cyls., looks like that pistons been suffering for a while, looks like specks of melted aluminum stuck in the carbon above it. Detonation/overheating, or both.
 
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That piston is seeing detonation. When a ring butts it cleanly snaps the crown off the top of the piston. Like if you hit it with a hammer. That piston has been melting.
 
Ain't no sense playin around with a bore o scope. I'd have that beeotch splattered all over the floor by now. It's GOTTA come apart.
 
At this point as others said, tear it down. You need to check all the bearings since a lot of metal became dislodged.
Did it give any signs of being super lean?
 
G70464 said:
At this point as others said, tear it down. You need to check all the bearings since a lot of metal became dislodged.
Did it give any signs of being super lean?
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Plug color was always good. Never heard detonation pinging. It did overheat when the NEW thermostat failed to open. Engine is coming out.
 
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