1. Check the cylinder bores in the block for taper, ovality, nicks and scratches. Start by carefully inspecting the top of the holes. If they are worn, a small ridge will form on their thrust side, which marks the top level of piston ring movement. The owner of the car can easily find out about the wear of the cylinder mirror even before disassembling the engine. Excessive oil consumption and blue smoke from the exhaust system are sure signs of worn cylinders and piston rings.
2. Measure the diameter of the cylinder under «wear ring» micrometer and compare it with the diameter at the bottom of the cylinder bore where the cylinder does not wear. If the difference between the two measurements exceeds 0.15 mm, it is necessary to bore the cylinders and install oversized pistons.
3. Cylinder bores must be machined to provide optimum operating clearance with new oversized pistons. The weight difference between any two of the six pistons must not exceed the limits specified in the specifications.
4. If the holes in the cylinders are slightly worn, but not so much that they need to be bored, you can install special oil scraper rings and pistons that will restore the necessary compression and stop the waste of oil in the engine. Several different sizes of repair parts are available for this purpose, and the manufacturer's instructions for installing them should be followed exactly.
5. Look for cracks and other damage in the cylinder block and crankcase, and also make sure that all water and oil channels are passable. Check that all cover gaskets are securely fastened to the crankcase and cylinder block. If any gaskets are questionable or leaking, unscrew the cap screws and remove it. Clean the cover and seating surface, install a new gasket, insert and tighten the screws. Check for leaks from the cooling jacket plugs.