I'm just looking for some quick input. I operate a fleet of Caterpillar 3500 series engines and have cylinder heads off of one engine for other reasons but noticed a build up of carbon on the cylinder wall thick enough the piston crown is hitting it. It is only in one portion of the cylinder and there are no other unusual deposits elsewhere. Is there a chance the injector is not atomizing properly out one port and fuel is hitting the cylinder wall? The wet appearance is because I hosed everything down with wd40 to prevent corrosion over night.