Cavitation Corrosion of Wet-Sleeve Liners in Heavy Duty Diesel Engines

Liner cavitation, or pitting, in Diesel Engines

Liner pitting, or cavitation-erosion, occurs along the thrust angle of the piston. The liner sits inside the block, and 'rings' like a bell every time that the cylinder fires. This ringing causes intense pressure changes at the cylinder wall, resulting in liner cavitation.

Bubbles form when the piston 'rings' the cylinder during the combustion explosion. These bubbles, imploding against the liner as it collapses them under pressure, gradually, but fatally, attack and bore through the liner.
The coolant additive nitrite, a major component of many SCA packages, protects the liner against the pitting action by forming a monomolecular, ultra thin oxide coat around the liner.

The ASTM D6210 specification requires that, to comply, an antifreeze must protect wet sleeve liners without any initial addition of an SCA. This usually means simply formulating the liner protection into the antifreeze, so the industry refers to this type coolant as "fully formulated". Such coolants may be formulated from conventional, carboxylate (organic) or hybrid chemical technologies. They usually, but do not always, contain nitrite or a combination of nitrite and molybdate to provide the liner protection.

Some heavy-duty engine manufacturers have adopted non-nitrite containing carboxylate inhibited ethylene glycol antifreeze / coolant technologies into their product lines. This adoption opens a new era in heavy-duty coolants and promises even more reliable and lower maintenance coolants than have previously been available.

Lighter diesel sometimes experience block cavitation, a problem that is also prevented by the use of ASTM D6210 type coolants and/or quality supplemental coolant additives