If there is a suspicion of coolant getting into the crankcase, it is recommended to check the tightness of the cylinder block on a special stand. To do this, having plugged the openings of the cooling jacket of the cylinder block, pump water at room temperature into it under a pressure of 3 kgf/cm². No water leakage should be observed within 2 minutes.
If oil is observed getting into the coolant, then without completely disassembling the engine, check for cracks in the cylinder block in the oil channel areas. To do this, drain the coolant from the engine cooling system, remove the cylinder head, fill the cooling jacket of the cylinder block with water and supply compressed air to the vertical oil channel of the cylinder block, which is located near the first bolt securing the cylinder head (see fig. 13, a). If air bubbles appear in the cooling jacket, replace the cylinder block.
They check whether the cylinder wear exceeds the maximum permissible value of 0.15 mm. The cylinder diameter is measured with an indicator bore gauge in four zones at a distance of 5, 15, 45 and 80 mm from the upper plane of the cylinder block both in the longitudinal and transverse directions of the engine. To set the bore gauge to zero, use the A.96137 gauge for the 2101 engine or the 67.8125.9501 gauge for the 21011. In the upper zone (at a distance of 5 mm from the upper plane) the cylinders are practically not worn out. Therefore, the difference in measurements in the upper and other belts can be used to judge the wear of the cylinders.
If the maximum wear of the cylinders exceeds 0.15 mm, then the cylinders are bored to the nearest repair size of the pistons (increased by 0.4 or 0.8 mm), leaving an allowance of 0.03 mm on the diameter for honing. Then the cylinders are honed, maintaining a diameter such that when installing the selected repair piston, the gap between it and the cylinder is 0.05-0.07 mm for 2101 engines and 0.06-0.08 mm for 21011 engines.
There may be deformations on the plane of the cylinder block joint with the head, so the plane of the joint is checked using a ruler and a set of feeler gauges. The ruler is installed along the diagonals of the plane and in the middle in the longitudinal direction and across. If the non-flatness exceeds 0.1 mm, the cylinder block is replaced.
The article is taken from an online resource: VAZBOOK.RU