2. Turn out spark plugs. Fully open the throttle and choke.
3. Disconnect the central high-voltage wire from the cover of the ignition distributor, connect it to ground.
4. Insert a compression gauge into the spark plug hole of the 1st cylinder (photo). Turn on the starter and watch the pressure gauge. On a healthy engine, the pressure should build up quickly. Low pressure after the first piston stroke and a slow build-up on subsequent compression strokes indicates worn piston rings. If the pressure is low after the first piston stroke and does not increase during subsequent compression strokes, then the cause is a leak in the valves or a leak in the cylinder head gasket (the cause may also be the formation of cracks in the head). Write down the highest compression value and repeat the procedure for the remaining cylinders.
2.4 Compression measurement
5. Repeat the procedure on the remaining cylinders.
6. If after introducing oil into the cylinder (10-15g) compression increased, it can be concluded that the piston rings are worn out. If the compression increases slightly, then the leakage occurs through the valves, or the cylinder head gasket.
7. If the compression is equally low only in two adjacent cylinders, then the most likely cause is a burnt gasket between these cylinders.
8. If the compression value exceeds the norm, then the combustion chamber is covered with soot. In this case, the cylinder head must be removed and carbon deposits removed.
9. With a strong difference in compression in the cylinders, the car should be taken to a service station to check the cylinder block by pressing.