Removing
1. For four-cylinder engines, remove the engine balancer.
2. Using a special tool, remove the ledge in the upper part of the cylinder, formed as a result of wear and deposits of combustion products. Do not attempt to remove the piston without removing the ledge or you will damage the piston.
3. Turn the engine over, crankshaft up.
4. Using feeler gauges, measure the side clearance of the connecting rods. If the clearance exceeds the allowable limits, the connecting rod must be replaced. If you have any doubts, contact the experts.
5. If the connecting rods and connecting rod caps are not numbered, number them.
6. Loosen the nuts on each connecting rod cap in 1/2 turn increments. Tighten the nuts, and remove the cover of the first connecting rod and the bearing shell.
7. Remove the bearing shell and remove the connecting rod with the piston. In order not to damage the necks of the connecting rod bearings, put pieces of hose on the connecting rod bolts.
8. Remove the rest of the connecting rods and pistons in the same way.
9. Fold the elements of each of the pistons separately so as not to confuse them.
Examination
1. Remove the piston rings with a piston ring installer, being careful not to scratch the piston.
2. Using a wire brush or fine sandpaper, clean the piston head from deposits.
3. Using a special tool or a piece of a broken piston ring, clean the piston ring grooves.
4. After removing all deposits, clean the pistons and connecting rods with a solvent and dry them.
5. If the pistons and cylinder walls are not badly worn and the cylinders have not been bored, new pistons do not need to be installed.
6. Carefully inspect all pistons for cracks on the piston skirt and on the surface around the connecting rod pin.
7. Inspect pistons for scratches, nicks, burnt areas, or corrosion.
8. If the piston skirt is severely scratched, the cause is overheating or abnormal combustion of the fuel mixture. In this case, it is necessary to carefully check the lubrication and cooling systems of the engine.
9. The presence of a hole in the piston head indicates abnormal combustion of the fuel mixture (pre-ignition occurs). Causes may include a leaking intake manifold, poor fuel mixture, incorrect ignition timing, exhaust system problems. Corrosion spots on the piston mean that coolant is leaking into the combustion chamber.
10. Measure the side clearances of the piston rings. If the clearance exceeds the allowable limits, the piston must be replaced.
11. Measure the clearance between the piston and the cylinder, to do this, measure the diameter of the piston perpendicular to the piston pin and measure the diameter of the cylinder. Subtract the piston diameter from the cylinder diameter. If the gap exceeds the allowable limits, the cylinder must be bored and a new piston and new piston rings installed.
12. Check clearance between piston and connecting rod.
13. Inspect the connecting rods for cracks or other damage. For a more detailed verification of pistons and connecting rods, contact the experts.