The piston / connecting rod assemblies must be cleaned and the original piston rings should be removed before proceeding with the inspection. During engine reassembly, it is necessary to use new piston rings. Take caution not to damage the pistons while removing rings from them using a piston ring installer. Use a handheld brass wire brush or fine emery / solvent cloth in cleaning which is followed by scraping off carbon deposits on top of the pistons. Caution must be exercised for not using wire brush mounted in drill motor as this will abrade soft piston material. Carbon deposits can be removed from ring grooves without damaging groove sides by employing a broken piece of an old ring or a piston ring groove cleaner. After removing deposits, clean the piston/rod assemblies with solvent and dry them out ensuring clear oil return holes in rears of ring grooves. New pistons are not needed unless there is no significant damage or wear on pistons/cylinder walls along with non rebored engine block. However, new piston rings must always be used when rebuilding an engine. Visually inspect each piston carefully for cracks around the skirt, pin bosses, and ring lands, as well as scoring, scuffing, holes in the crown of the piston and burned areas at its extreme edge. Small pits consisting of corrosion indicate coolant leakages that need to have their root cause addressed. An assessment of critical parameters such as: Piston Ring Side Clearance; Piston-to-Bore Clearance; Piston-to-Rod Clearance is necessary. If excessive side clearance or clearance beyond specifications is found, new pistons or reboring may be necessary.Crankshaft deflection indicates excessive wear hence should always receive attention because it will reduce performance speeds in that case it will result to inefficient operation.Scoring check should also be conducted through measuring Skirts are usually checked by measuring their width at several points along their length being sure to keep measurement perpendicular to cylinder bore axis.In order to determine if pistons must be removed for resizing or if they need to be replaced, it is best to take the piston/connecting rod assemblies to an automotive machine shop as they have the knowledge and tools. Additionally, the rod cap can be temporarily removed so that connecting rods can be inspected for cracks and other damages; bearing surfaces should also be cleaned and scrutinized for defects. This may require installation of new or rebuilt rods depending on the engine in question.
