Pic. 2.20. Oil pressure switch
Remove the oil pressure switch (pic. 2.20).
Check the cylinder block for chips, corrosion, scale deposits and rust. Also, check for cracks or other damage. Replace the block of cylinders at detection of considerable defects.
Pic. 2.21. Checking the cylinder block for warpage
Using a straightedge and a flat feeler gauge, check the warping of the mating plane of the cylinder block under the gasket. Before checking, make sure that the surface of the cylinder block is free of old gasket residue and foreign particles (pic. 2.21).
Rated value: 0.03 mm or less.
Limit value: 0.15 mm or less.
Pic. 2.22. Cylinder diameter measurement
Measure the diameter of the cylinders with the indicator-caliper in three zones in height in the directions «A» And «IN» (pic. 2.22).
If the out-of-roundness (ovality) or the taper of the cylinder is greater than the maximum permissible value, or there are scratches or signs of seizing on the cylinder mirror (badass), then the cylinders of the block should be bored to the appropriate repair size and honed. After repair of the block of cylinders establish pistons and piston rings of the corresponding repair size.
Nominal cylinder diameter: 76.50–76.53 mm.
Cylinder taper limit: 0.01 mm or less.
If there is an influx along the perimeter of the cylinder in its upper part (ridge wear), remove it with a special tool.
Four overhaul pistons are produced (enlarged) sizes.
Repair size and piston mark:
- 0.25 mm - 0.25;
- 0.50 mm - 0.50;
- 0.75 mm - 0.75;
- 1.00 mm - 1.00.
When repairing (boring and honing) cylinders to the repair size, calculate the bore diameter of the cylinder so that as a result of the repair, the nominal clearance between the piston and the cylinder is provided. Check that all installed pistons are the same oversize.
Standard piston diameter measurements are taken at a distance of 47 mm from the piston crown.
Clearance between piston and cylinder (set limit for new parts): 0.025–0.045 mm.