KIT-HYD CYLINDER SEAL 5579977 - Caterpillar

EnginesIt is important to inspect the piston skirts during the in-chassis inspection before an engine overhaul. This inspection is necessary to find if the overhaul will be done in-chassis or out of the vehicle.
Cracks in piston skirts can be caused by several factors, such as unusually high load applications, frequent lug operation of the engine, frequent high rpm operation, or too much clearance between piston and bore. These conditions cause increased impact loads on the piston skirt which some times results in skirt damage.
When the oil pan is removed, check for cracks or large breaks in the piston skirt. Check the oil pan for large pieces of piston material. Use the Guideline For Reusable Parts, "Pistons and Cylinder Liners" (Form No. SEBF8001-01) to see if there is any other damage which prevents reuse of the piston. If the piston is damaged, check the bore for damage. If there is major bore damage, it is some times necessary to remove the engine from the vehicle.
Other procedures are also necessary during the critical inspection before an overhaul. See the chart "Repair Determination Procedure", Form No. SENR2059. Make a note of this article on the chart in the section "Lower End Inspection".