However, before the inspection process may be done, most of the piston/connecting rod assemblies must be washed and most of the original piston rings must also be removed from the pistons with new one used in the reconditioning. Hold the piston rings between your thumb and forefinger and with the help of piston ring installation tool gently take the rings off from the pistons without scratching the latter. Clean all of the carbon off the top of the piston using a small hand-held wire brush or fine emery paper; DO NOT use a wire brush with a motor attached to it as this is likely to wear a groove in the softer surface of the piston. Carbonaceous deposits from the groove or rust and scale from out sides should be scrape out using a piston ring groove-cleaning tool or a piece of metal broken off the old ring that fits the groove should be used and while doing this should not remove any metal or mars the groove. Once the deposits have been empties, wash the piston/rod assemblies with solvent and blow them off with compressed air, making sure that the oil return holes and the hole in the lower end of each rod are open. Only when the pistons and cylinder walls are worn or damaged and when the engine block is not rebored new pistons are not mandatory, however new piston rings have to be always fitted in any rebuild. Every piston should ought to be checked for cracks, scoring, scuffing, holes and burned out areas since these are the symptoms of overheating, abnormal combustion or spark knock therefore, checking the cooling and lubrication system. Pitting type of corrosion is evidence of coolant penetration into the combustion chamber or crankcase, and this has to be rectified to avoid future occurrences. Check with a new piston ring and a feeler gauge at certain points of a piston ring groove for the correct ring and use the values to compare with the standard then check for the misfit and if it is too wide the piston needs to be replaced. Ensure that the piston to bore clearance is correct by comparing the bore and piston diameter, if not do the following, rebore the block and put new piston and rings in it. Raise the piston and try to turn the piston and rod in opposite directions; if the two parts of a kit exhibits considerable play, it will have to be "repaired." If pistons have to be pulled out from the connecting rods, should be taken to the automotive machine shop for bend and twist. Finally, check for crack and damages with the connecting rods by removing the rod caps and cleaning the bearing areas, for nicks, gouges and crack then replace old bearings and tighten the rod cap by fingers only and new connecting rods should be fitted if the engine is being rebuked for connecting rod knock.