Method for determining and checking the repair size of the cylinder

Basic measures to reduce cylinder wear

Air red wear mainly occurs under certain adverse conditions, so try to avoid it. The main measures to reduce cylinder wear are as follows:

1) Starting the engine should be "less frequent and as warm as possible". "Less" means

Not suitable for frequent use. "Slow" means running at low speed after starting, and "warm" means waiting until the engine temperature is normal before starting.

2) Keep the engine at normal operating temperature during operation. Too low a temperature will cause corrosion and cylinder wear, and too high a temperature will make the oil thinner, impair lubrication, and easily lead to adhesive wear.

3) Clean and replace the air filter regularly.

4) Make sure the engine is well lubricated. Frequently check the quantity and quality of engine oil, and clean the oil filter in time.

5) Improve the quality of repairs.

Determining the repair size of the cylinder

Cylinder wear exceeds the allowable limit, or there are serious scratches, grooves and pits on the cylinder wall, the cylinder should be repaired according to the level of repair and an oversized piston should be selected to match the cylinder. rings to restore correct geometry and normal fit clearance. The formula for calculating the repair size of the cylinder is as follows:

Repair size = maximum cylinder diameter + allowance for boring and honing

The allowance for boring and honing is typically 0.10-0.20mm. The estimated repair size needs to be compared with the repair class. If it matches a certain repair class, it can be repaired according to a specific repair class. If it does not match the repair class, for example, the estimated repair size is between two repair marks. If the time is too long, repair cylinder should be carried out according to the largest repair series.

If the cylinder wear exceeds the maximum overhaul, a cylinder liner must be installed.


When replacing an engine piston and liner, if one cylinder needs to be bored, honed, or replaced, the remaining cylinders should be bored, honed, or replaced at the same time to keep the engine cylinders consistent.

How to check a cylinder

In addition to checking for scratches or damage to the cylinder wall, the diameter of the cylinder is also measured to calculate the roundness and cylindricity of the cylinder.

(1) Install and calibrate the measuring cylinder pressure gauge

1) Select a suitable adapter rod according to the standard size of the cylinder being tested, and after installing it, do not temporarily tighten the fixing nut.

2) Fit the outer diameter micrometer to the standard size of the cylinder being tested and place the installed cylinder gauge in the micrometer.

3) Rotate slightlyconnecting rod so that the pointer of the cylindrical gauge itself rotates about 2 mm, set the pointer to the zero position of the scale, tighten the connecting rod fixing nut and repeat the zero calibration once. for the measurement to be correct.

(2) Measurement method

1) Use the most cylindrical meter, hold the heat-insulating sleeve with one hand, and with the other hand, hold the bottom of the pipe close to the body.

2) Retract the calibrated measuring rod in two directions, parallel to the crankshaft axis and perpendicular to it, and take three positions (segments) along the cylinder axis, including top, middle and bottom, to measure Six values, as shown in the figure:< /p>

3) When measuring, keep the movable measuring rod of the measuring cylinder sensor perpendicular to the axis of the cylinder for accurate measurement. When the arrows of the front and rear turn meters point to the minimum number, this means that the active measuring rod is perpendicular to the axis of the cylinder.