Will a hairline crack in a connecting rod show up in a compression test?
SubscribeNope, it isn't a sealing part of the combustion chamber, in fact it's not part of the combustion chamber at all. Compression test only tests the integrity of the head gasket, valve / valve seats, and piston rings. The only way I know to find a cracked conn rod is to remove it from the engine and get it NDT'd.
Dave
Dave