Cracked Piston
Race Director
Joined: May 2006
Posts: 18,735
Likes: 2,582
Le Mans Master
Joined: Oct 2010
Posts: 6,937
Likes: 848
From: melbourne florida
2023 C3 of the Year Finalist - Modified
How does the front edge of the dome look? It's a forged piston it could be a cosmetic defect send a picture to the manufacturer.
I'd say cosmetic but it seems like it follows an arc. You could take a sanding disc and see if it polishes out fairly quickly.
I'd say cosmetic but it seems like it follows an arc. You could take a sanding disc and see if it polishes out fairly quickly.
Le Mans Master
Joined: Oct 2010
Posts: 6,937
Likes: 848
From: melbourne florida
2023 C3 of the Year Finalist - Modified
I agree it looks like a blemish. Maybe probe it with a razor blade see if you can clean up the recess and just see if it looks ok. Years ago on race engines some of us would actually polish the top of the piston. We found it didn't do anything but we tried lots of things . Laugh if you will but we had to experiment a lot to get an edge so you don't have to.
Pro
Joined: Aug 2010
Posts: 651
Likes: 452
From: Napa, CA
Looks like a fracture to me. Typical causes are detonation and/or physical contact with the cylinder head due to improper deck clearance or rod stretch. Looks like it may be propagating to or from the backside of the upper ring land.
Disclaimer: The value of this opinion is worth exactly what you’re paying for it.
Disclaimer: The value of this opinion is worth exactly what you’re paying for it.
Safety Car
Joined: May 2001
Posts: 4,759
Likes: 1,647
From: Fairfax Virginia
That mark on the left side of the picture is likely nothing. The mark on the right side is the one that worries me. If I had a piston like that I would likely replace them all. That crack/line follows the right side of the top inner ring of the piston's perimeter and that would make me very suspicious about the part.
Isn't there a way to check the aluminum without destroying it? Is this a viable option for testing a component like the piston?
Dye Penetrate spray is used on aluminum cylinder heads and blocks to find imperfections and cracks.
I thought there was a material that lets you find cracks in aluminum similar to Magna Flux? A positive answer from a engine machine shop would be the only way I would trust it.
Isn't there a way to check the aluminum without destroying it? Is this a viable option for testing a component like the piston?
Dye Penetrate spray is used on aluminum cylinder heads and blocks to find imperfections and cracks.
I thought there was a material that lets you find cracks in aluminum similar to Magna Flux? A positive answer from a engine machine shop would be the only way I would trust it.
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
That mark on the left side of the picture is likely nothing. The mark on the right side is the one that worries me. If I had a piston like that I would likely replace them all. That crack/line follows the right side of the top inner ring of the piston's perimeter and that would make me very suspicious about the part.
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