- A device for measuring compression.
Attention: Diesel engine requires a device with a large measuring range.
Compression should be checked every 80,000 km. On gasoline engines, the spark plugs must be removed. In this case, it is recommended to combine this work operation with the change of spark plugs. On diesel engines, the glow plugs are turned out during the compression test.
The results of the compression test allow you to draw conclusions about the condition of the engine. Namely, the check allows you to make a conclusion about the wear of valves or pistons (piston rings), in addition, according to the results of the check, it can be determined whether the engine can be repaired by replacing individual parts or whether it needs a major overhaul.
The compression difference between the individual cylinders must not exceed 1.5 bar. Exceeding these values is a sign of defective valves, wear of piston rings or working surfaces of cylinders. When the wear limit is reached, the engine must be overhauled or replaced.
The value of the measured compression is of secondary importance, since it also depends on the measuring device used. Compression on gasoline engines must be at least 10 bar, and on diesel engines at least 20 bar.
To check the compression, the gasoline engine must be warmed up to operating temperature, and the diesel engine must be cold.
Gasoline engines
A well-charged battery is a prerequisite for the test.
Switch off the ignition.
Remove the cover from the fuse box. It is located on the left rear in the engine compartment next to the brake master cylinder.
Remove the main relay -1- and the fuel pump relay -2- so that no fuel is injected during the test.
Remove all spark plugs.
Crank the engine a few revolutions with the starter to remove carbon deposits.
Attention: The gearbox is in neutral position, the handbrake is applied.
Connect a compression tester to the spark plug hole in accordance with its instruction manual.
Have an assistant press the gas pedal all the way down and keep the foot on the pedal in this position throughout the test.
Crank the engine about 8 revolutions until the gauge stops increasing.
Consistently check the compression in all cylinders and compare with the specified value.
Finally, screw in the candles.
Install the main relay and the fuel pump relay. Close the fuse box cover.
Diesel engine
Test condition: Charged battery.
Unscrew the cover of the electronics box on the right side of the engine compartment.
Remove the main preheat relay and connector from the preheat time control box.
Disconnect the electrical wires from the glow plugs and unscrew the glow plugs with the appropriate key head.
Instead of glow plugs, screw in a compression tester.
Crank the engine with the starter until the pressure build-up stops. Write down the result. Repeat the test on all cylinders.
After checking, screw in and tighten the glow plugs to 25 Nm. Pre-coat the threads of the candles with copper paste "CRC".
Connect the wires to the glow plugs with a tightening torque of 5 Nm.
Insert the main relay, connect the connector to the glow time control unit.
Close the electronics box.