The pistons/connecting rods cannot be inspected while still contained with the engine and therefore require cleaning and the removal of the original piston rings from the pistons to be replaced with new piston rings upon reassembly. Some of the cas uses include the following piston ring installation tool to cut out the old rings with out damaging the pistons in anyway. Get rid of all the carbon deposits you find on the top of the piston using the hand wire brush or fine emery cloth never use the wire brush that is mounted on the motor because this will lead to erasing of the surface finish of the softer material used on the construction of the Piston. Carbon deposits should be scraped out from the ring grooves using a piston ring groove cleaning tool and if this is not available, a piece of old ring can just as well be used, but care should be taken not to remove any metal or damage the grooves. After the deposits have been removed, wash out the piston/rod assemblies between solvent and dried with compressed if available. If the pistons and cylinder walls arent skint or worn too thin and if the engine block is not rebored new pistons may not be required; but new piston should always be fitted when an engine is being rebuilt. The skirt, pin bosses, and ring lands of each piston should be checked for cracks, while scoring, scuffing and any holes on the piston crown and burned areas on the edge of the crown which could be as a result of overheating or any abnormal combustion should also be checked for. Pitting corrosion means that there is a leakage of coolant into the combustion chamber or crankcase which must be rectified. Piston ring side clearance must be measured by installing a new piston ring to each groove and then using the feeler at different sections on the groove bearing in mind, each groove take the right ring. Engine bore wear can be checked by measuring the bore and piston diameter of the particular engine at the cylinder that depends on the type of the engine; if the piston to bore clearance goes beyond certain levels, this will require reboring of the block and new pistons and rings. Piston-to-rod clearance can be determined by rotating them in opposite directions, where significant looseness means there is wear and need for adjustment that may mean that the piston, rod and pins may have to be taken to an automotive machine shop for resizing. If pistons have to be pulled off the connecting rods, these should also be taken to the machine shop to check them for bend and twist, while the connecting rods should be examined for cracks and damage; old bearing inserts should also be temporarily removed for cleaning before reassembly.