Before the inspection process it is necessary to clean the piston/connecting rod assemblies, and to remove the original piston rings from the pistons, and it is necessary to use new piston rings when assembling the engine. With the help of piston ring installation tool, it is now time to take out the rings from the pistons without scratching them in any way. Most of the carbon deposits can be removed by using a handheld wire brush or fine emery cloth to scrap all the carbon from the top of the piston after doing this, do not use a wire brush which is mounted on a drill motor or any caustic chemicals. Remove all the carbon from the ring grooves with a piston ring groove cleaning tool or a piece of a worn out ring in a manner that you do not remove any metal or damage the grooves. After cleaning the deposits, the piston/rod assemblies should be cleaned with solvent, followed by blowing compressed air through them; the oil return holes should be free. If the pistons and cylinder walls are not explain worn or damaged and the engine block is not rebored new pistons are not always required but new piston rings should always be fitted when an engine is rebuilt. Each piston should be examined for cracks, score marks, scratches, holes, and burnt areas as such conditions might be as a result of over heating or abnormal combustion and thus requires the cooling and lubrication systems to be checked thoroughly. Pitting corrosion is characterized by small pits which are likely to be as a result of coolant leakage and should not be encountered again. Use the feeler gauge to measure the side clearance on the ring end at several locations around each groove, and install the correct ring in the correct groove; if the side clearance is more than allowed, the new pistons will have to be bought. To inspect the piston-to-bore clearance, first, measure the bore and piston diameter and make sure that they are compatible; if the clearance is more than the required that is stated, then the block has to be rebored and the new pistons and rings fitted. Check the piston to rod clearance by rotating the piston and the rod in the opposite direction, if there is end play one must have it corrected that could mean that the piston and rod must be resized and new pins fitted at an automotive machine shop. If the pistons have to be taken out from the connecting rods take them to an automotive machine shop and get them checked for bend and twist. Another step is to check the connecting rods for cracks and damage of any kind, with the rod caps and old bearing inserts being removed temporarily for that, the surfaces being cleaned and then checked for any nicks or scratches before the bearings are replaced and the caps are tightened. If you are doing a rebuild because of a connecting rod knock, new rods should be used.