dieseldummy
Lost in time
Exactly one year and one month ago I repowered my '93 with a 6.2 shortblock covered in 6.5 gear. The 6.2 was punched out .020" and fitted with Ebay military surplus pistons... I just tore the motor out tonight since it wouldn't fire on one cylinder and was puffing out blowby something terrible...
Sure enough there was a cracked piston... I suspsect that they are Silvolite junk since there are no markings on them and they look similar to a Silvolite. They appear to start cracking in the wrist pin bores and go up and across the crown. There are some shallow surface cracks that appear to be heat related. They are in the ricardo recess where the casting isn't very finished.
The red outlines are of the main crack and some surface heat cracks. The blue outlines are from a tragic glow plug incident. The yellow is where material would be on a Mahle or stock piston.
I'm going to weigh the junk pistons and compare weight to a stock piston. Holding them side by side the .020" feels lighter than the stock bore piston. Overall these pistons are of poorer quality than the stock Bohn, Zollner, or aftermarket Mahle. The unmachined parts of the casting are very porus. The wrist pin bores are about 2 MM thinner than the above mentioned pistons and seem to be made out of an inferior alloy. I could understand the cracks being a result of the glow plug inhalation, but the worst cracked one has the least amount of GP damage. Luckily the block is ok. Buyer beware of surplus pistons...
Sure enough there was a cracked piston... I suspsect that they are Silvolite junk since there are no markings on them and they look similar to a Silvolite. They appear to start cracking in the wrist pin bores and go up and across the crown. There are some shallow surface cracks that appear to be heat related. They are in the ricardo recess where the casting isn't very finished.
The red outlines are of the main crack and some surface heat cracks. The blue outlines are from a tragic glow plug incident. The yellow is where material would be on a Mahle or stock piston.
I'm going to weigh the junk pistons and compare weight to a stock piston. Holding them side by side the .020" feels lighter than the stock bore piston. Overall these pistons are of poorer quality than the stock Bohn, Zollner, or aftermarket Mahle. The unmachined parts of the casting are very porus. The wrist pin bores are about 2 MM thinner than the above mentioned pistons and seem to be made out of an inferior alloy. I could understand the cracks being a result of the glow plug inhalation, but the worst cracked one has the least amount of GP damage. Luckily the block is ok. Buyer beware of surplus pistons...
