Before inspection, clean piston/rod assemblies and remove old piston rings. Use tools to remove carbon deposits without damaging the pistons. Clean assemblies with solvent and dry with compressed air. If pistons and cylinder walls are undamaged, new pistons may not be needed, but always use new rings. You can inspect each piston for cracks, scoring, and signs of overheating or coolant leakage. Check for excessive wear and if needed, have pistons, rods, and pins resized at a machine shop. Replace old bearing inserts and tighten rod caps.