60-67 Buying Diesel 7/15/14 11:37 AM Page 66
Diesel Pistons steel sleeves. The wet liners that are used in heavy-duty diesel engines are essentially drop-in cylinders that are sealed at the top and bottom with a flange and o-rings. The amount of slip fit will vary depending on the application, so follow the OEM recommendations. Wet liners are thicker than repair sleeves or cast-in-place sleeves because they have no metal around them to provide added support. As with dry sleeves, ductile iron liners provide the extra strength needed for high output applications. Wet liners can fail from fatigue cracking, or as a result of cavitation erosion. Every time the cylinder fires, it expands and contracts slightly causing small bubbles to form in the coolant that is circulating around the outside of the liners. When the bubbles implode, they do so with great force and chip away at the outside of the liners.
Over time, cavitation can pit and erode away so much metal that the liner eventually perforates and allows coolant to leak into the cylinder. This can cause the engine to overheat, or it can even hydrolock the cylinder.
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Cavitation erosion is often the result of coolant neglect, or using a coolant that does not contain “Supplemental Coolant Additives.� These additives include nitrite and/or molybdate that form a protective oxide film on the outside