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2. Remove carbon deposits from piston ring grooves using a tool (photo on the left) or an old piston ring (photo on the right).
3. Wash the pistons and connecting rods with solvent, thoroughly clean the oil drainage holes in the piston grooves and the hole in the connecting rod.
4. If there are no significant signs of wear and if the cylinders do not require boring, then the pistons should not be replaced. Normal wear is manifested in the form of traces of uniform vertical wear on the piston friction surface and in the form of a slight weakening of the fit of the upper compression ring. However, replacement of piston rings is mandatory.
5. Carefully check for cracks in the piston skirt, piston pin bosses and piston ring seats.
6. If there are chips and scuffs on the piston, this indicates frequent overheating of the engine. In this case, a thorough check of the lubrication and cooling systems is required. Burning of the piston bottom indicates that the engine is running with an incorrect ignition timing setting. The cause of burning of the piston bottom at the edges is usually abnormal combustion (detonation). If the above defects are detected, their cause must be found and eliminated.
7. Piston corrosion in the form of small pits (pitting) indicates penetration into the combustion chamber (and also in the crankshaft housing) coolant.
8. Measure the gap between the groove and the new ring. If the gap exceeds the specified limit, the piston should be replaced.
9. Check the clearance between the piston and the cylinder by measuring the cylinder diameter (see subsection 3.3.10) and the piston diameter of a given cylinder.
10. The piston diameter is measured perpendicular to the axis of the piston ring directly under the pin. If the gap exceeds the established limit, the cylinder block must be bored, and the pistons and rings must be replaced with repair ones.
10. Check the clearance between the piston pin and the connecting rod head by rocking the piston and connecting rod in opposite directions. If the clearance is noticeable, then this connection needs to be repaired.
11. Checking the connecting rod heads and their deformation, as well as the corresponding repairs, are carried out in a car service.
12. Check the connecting rods for cracks and other damage. Remove the connecting rod bearing caps, take out the bearings, wipe the seating surfaces on the cap and on the connecting rod, check for cracks, scratches and burrs. After checking, assemble the connecting rod, install the bearings in place, tighten the nuts by hand.
The material was taken from a resource: ToyotaMAN.ru
Attention! If the engine is disassembled due to seizure, the connecting rods must be replaced.