To check compression, it is recommended to use compression testers for petrol engines of type G-324 from «Triscko» (Taiwan) or KA-6721K from «KT TOOLS» (Taiwan).
Place the vehicle on a horizontal surface, apply the parking brake and warm up the engine.
Place the gear lever in neutral, switch off the ignition and open the bonnet.
Disconnect the plug connector from the ignition module or coil.
Remove the leads from the spark plugs and unscrew the spark plugs.
Note: Carry out the compression measurement work in pairs, switching on the starter with the ignition switch.
Check the compression in the first cylinder.
Important! The check must be carried out with the air and throttle valves fully open.
Insert the rubber cone of the compression tester tip into the threaded hole for the spark plug in the cylinder head and press it to ensure the combustion chamber is sealed.
By switching on the ignition switch, turn the engine crankshaft until the readings of the compression tester needle stabilise (from 5 to 7 seconds).
Set the compression tester needle to zero by pressing the reset button.
Check the compression in the second, third and fourth cylinders in the same way.
The compression in all engine cylinders must be at least 1.0 MPa (10 kgf/cm²) and must not differ between the different cylinders of the same engine by more than 0.1 MPa (1 kgf/cm²).
If the compression reading is low in one or more cylinders, carry out fault finding:
- Pour 20 to 25 cm³ of clean engine oil into the cylinder being checked with reduced compression.
- Repeat the compression measurement operations.
- A higher compression reading in this case will indicate a breakage or sticking of the piston rings.
- If the compression tester reading does not change, the cause of the reduced pressure is poor seating of the valves or damage to the cylinder head gasket.
Screw in the spark plugs and connect the high-tension leads to them.
Close the bonnet, start the engine and check its operation.
