2. Disconnect the negative battery terminal.
3. Remove glow plugs from all cylinders.
Attention.
- Before removing, clean adjacent surfaces to prevent foreign material from entering engine.
- Be careful not to damage the glow plugs when removing.
- Do not hit the glow plugs.
4. Disconnect the fuel injector wire connectors to prevent fuel injection during the test.
5. Install a compression gauge with an adapter (Mot.1772 according to Renault catalog) into the hole for the glow plug.
6. Turn the ignition switch to the START position to crank the engine with the starter. After the readings of the arrow of the compression gauge stabilize, read the compression value and the engine speed. Carry out the described procedure for each engine cylinder.
Attention. To check the compression in the engine cylinders, it is necessary to use a fully charged battery to obtain the desired crankshaft speed.
Note.
- If the engine speed does not match the required, check the density of the electrolyte in the battery. Make sure the battery is fully charged and repeat the measurement of the crankshaft speed.
- If the compression value is below the maximum allowable value, check the valve clearances and the condition of the parts associated with the combustion chamber (valves, valve seats, pistons, piston rings, cylinder bore, cylinder head, head gasket). After checking, check the compression in the cylinders again.
- In a cylinder with a low compression value, add a small amount of oil through the spark plug hole and check the compression again.
- If, after adding oil, the compression in these cylinders increased, then the piston rings are most likely worn or destroyed. Check the condition of the piston rings and, if necessary, replace them with new ones.
- If compression remains low, the cause may be poor condition of the valves and/or valve seats. Check the condition of the valves and seats for damage. Replace valve or valve seat.
- If a low compression value is observed in neighboring cylinders, then a defective cylinder head gasket may be the cause. Replace the defective gasket with a new one.
7. After checking, install the removed parts.
8. Start the engine and check that it runs smoothly.
9. Perform troubleshooting. If necessary, clear stored trouble codes.