OM 617 – Checking compression pressure

Testing data in bar positive for hot engine

Compression pressure normal 22-24
Minimum compression pressure ca. 15
Permissible difference between any two cylinders max. 3

Tightening torques Nm (kpm)- – – – – – –
Cap nuts of injection lines 25 (2.5)——
Injection nozzles in precombustion chambers 70-80 (7-8)

Check compression pressure at 80 OC coolant temperature. The compression pressure can be checked through the spark plug hole or the precombustion chambers. If engine fails to reach minimum combustion pressure, check cylinders for leakage (00-1 20).

Checking
1 Unscrew all glow plugs or injection nozzles.
2 Connect remote starter to terminals 30 and 50 on starter.
Positive battery terminal can be used in place of terminal 30.

3 With transmission in neutral, crank engine several times to eject carbon deposits.
Caution:
On engines featuring injection pumps with mechanical governors, first move stop lever (stop) in direction of engine so that injection pump will not inject fuel.

4 Screw connector into glow plug hole or precombustion
chamber of each cylinder in turn.
5 Connect compression pressure recorder.
6 To check pressure, crank engine by 8 revolutions while using full throttle.

On engine models 617 in general and on models 615, 616 featuring injection pumps with mechanical governors, do not use full throttle because these en-gines do not have throttle valves.
7 Prior to inserting the injection nozzles, fit new nozzle plates.

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