2. Carefully spread the ring towards the top of the piston. To prevent the ring from falling into an empty groove when removing, place two or three old probes under the ring (see photo).
3. Scrape off carbon deposits from the piston crowns. After removing the upper coarse layer of carbon, clean the piston crown with a wire brush by hand (or cloth-based sandpaper).
4. Carefully remove carbon deposits from the piston grooves using an old broken piston ring.
5. Wash the piston assembly with the connecting rod in solvent, dry thoroughly. Make sure that the oil drain grooves in the piston ring grooves are clean.
6. Carefully check up existence of cracks on a skirt of the piston, on bosses of a piston pin and in places between grooves of piston rings.
7. Check for chips and scuffs on the rubbing section of the piston skirt, traces of burning along the edges of the bottom. If chips and scuffs are observed, then this indicates frequent overheating of the engine, one of the reasons for which may be abnormal combustion of the fuel mixture. In this case, a thorough check of the power supply, lubrication and cooling systems is required. Traces of melting on the side surface of the piston indicate a breakthrough of gases from the combustion chamber. Piston head burning or burnt areas along the bottom edges indicate abnormal engine operation due to incorrect ignition timing (too early ignition), or due to detonation. If these flaws are found, then their cause must be found and eliminated, otherwise the manifestation of the causes of such wear is possible in the future. The reasons for the abnormal operation of the engine may be air leakage on the intake manifold, incorrect ignition timing, failure of the fuel injection system.
8. Piston corrosion in the form of small pits (pitting) indicates penetration into the combustion chamber (as well as in the crankcase) coolant. Here again, you need to find the cause and eliminate it.
9. Measure the diameter of the piston skirt with a micrometer perpendicular and parallel to the axis of the piston pin and compare the result with the standard. The size group of the piston is stamped on its bottom. If the piston wear exceeds the maximum allowable value, the piston must be replaced. Determine the clearance between the piston and the cylinder by subtracting the piston diameter from the cylinder diameter, measured in the same direction. If the backlash exceeds norm replace the piston. If the piston moves freely in the upper part of the cylinder and moves with difficulty in its lower part, then the taper of the cylinder obviously exceeds the norm.
10. Carefully check up presence of such damages on rods, as cracks on heads near piston pins and in junction-rod bearings installation places. Check if there is deformation of the connecting rod body (twist or bend). Damage to the connecting rods is unlikely and only occurs in cases of engine seizure or severe overheating. A thorough check of the connecting rods can only be performed in a car service.
11. On all engines under consideration, the piston pins are inserted with an interference fit into the connecting rod head. Remove the pistons from the connecting rods should be in a car service.
Attention! It is highly discouraged by the manufacturer to disassemble the piston-rod assembly. The piston is changed as an assembly with the connecting rod.
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