Gasoline engines
1. Warm up the engine.
2. Turn off the ignition.
3. Relieve pressure in the supply system (see chapter «Engine management system»).
4. Check all spark plugs.
5. Disconnect the central wire from the ignition distributor (ignition coil wire).
6. Attach the compressor to cylinder #1.
7. Fully open the throttle by depressing the accelerator pedal all the way.
8. Scroll the engine with a starter and fix the maximum reading of the compression gauge.
9. Repeat measurements for each cylinder.
To ensure the required engine speed, the battery must be fully charged.
For GA engines, the compression values correspond to an engine speed of 350 min-1, for SR engines - 300 min-1.
10. If the compression in one or more cylinders is low, pour a little engine oil into the cylinder through the spark plug hole and repeat the measurement.
If the compression increases after adding oil, then the piston rings are most likely worn or damaged. Replace the rings after checking the piston.
If the compression remains at the same level, then it is possible that the valve is sticking or its fit is broken. Check and repair valves and/or their seats. Replace parts with significant damage or wear.
If the compression is low in two adjacent cylinders, then the cylinder head gasket or valves of both cylinders are most likely damaged.
Diesel engines
1. Warm up the engine to normal operating temperature.
2. Disconnect the fuel supply pipes from the injectors and loosen their fastening to the injection pump. Loosen the tube clamps. Use two wrenches to prevent the holders on the injection pump from turning.
3. Remove the outlet tube. To avoid breaking the tube, hold the nozzle holder with the second wrench.
4. Remove all nozzles.
5. Disconnect the connector from the solenoid valve that shuts off the fuel supply.
6. Attach a compression tester to a head of cylinders.
7. Scroll the engine with a starter and read the compression gauge. Compression value at 200 rpm-1, kPa (kgf/cm2):
- Rated: 3138 (32)
- Minimum: 2452 (25)
- Difference between cylinders no more: 490 (5)
8. If the compression is low, pour about 3 ml of engine oil into the cylinder through the nozzle hole and repeat the measurement. Interpretation of results similar to gasoline engines (see previous subsection).
9. Install the nozzles, replacing the gaskets. New gaskets must be installed in the direction shown in the illustration.
Torque for injectors: 39-49 Nm.
10. Install the fuel outlet pipe. Nut tightening torque: 39-49 Nm.
11. Connect the supply pipes. Tightening torque for union nuts: 22-25 Nm.