2. Remove the valves from the cylinder head.
3. Before checking, clean all parts to be checked with cleaning agent and dry with compressed air.
4. Check that the parts are not scratched or show signs of impact or abnormal wear. If any defects are found, replace the parts with new ones.
5. Verify that the valves move freely in the guide bushings.
6. Measure the diameter of the valve head with a micrometer (D) and valve length (L).
7. Measure the diameter of the valve stem with a micrometer (d1) on distance (X1) equal to 41 mm for the intake valve or 31 mm for the exhaust valve.
8. Check clearance between valve stem and valve guide:
Note:
The clearance between the valve stem and the guide sleeve can be measured in two ways.
The clearance between the valve stem and the guide sleeve must be:
- for intake valve: 0.02 -0.05 mm;
- for exhaust valve: 0.03 ~ 0.06mm.
Measuring the Gap between the Valve Stem and the Guide Using a Dial Gauge
- Install pressure plate to measure cylinder liner protrusion (Mot. 252-01) on the cylinder head.
- Remove the valve by 25 mm.
- Install dial gauge with support.
- Place the dial indicator probe against the valve head at right angles to the valve stem.
- Push the valve head towards the dial gauge.
- Reset the dial indicator.
- Push the valve head away from the dial indicator.
- Write down the value displayed on the dial indicator.
- Calculate the actual valve stem-to-guide clearance by dividing the dial gauge value in half.
Measuring the gap between the valve stem and the guide sleeve using a micrometer and an inside gauge
- Measure the inside diameter with a caliper (2) valve guide.
- Measure the diameter of the valve stem with a micrometer (3).
- Calculate the actual clearance value by subtracting from the inside diameter of the guide bush (1) valve stem diameter (2) and divided in half.
9. Check valve seat depth:
Note: This check is performed if the valve is replaced. It must be ensured that the position of the valve head relative to the contact surface of the cylinder head is within the allowable range in order to ensure normal engine operation. If the position of the valve head is not correct, the engine may be damaged.
- Install dial indicator (5) with dial indicator support (Mot. 251-01) (4) on the cylinder head by placing them on a pressure plate to measure the protrusion of the cylinder liner (Mot. 252-01) (3).
- Place the dial indicator probe on the contact surface of the cylinder head.
- Reset the dial indicator.
- Measure and record the seating depth of each valve in the seats.
Note: The seating depth of the valve must be +0.07 mm (performance) up to -0.07 mm (deepening) for intake and exhaust valves.
- Remove the dial indicator with bearings from the cylinder head.