Testing Compression Pressure

Engine 604 Shown, Engine 606 Similar:

NOTE: Numbers in parentheses ( ) indicate a component or tool in the associated illustration.

1. Warm engine up to normal operating temperature (about 80°C)

NOTE: Test compression pressure when engine at normal operating temperature

WARNING:
^ Risk of explosion as a result of fuel vapors igniting.
^ Risk of poisoning as a result of inhaling fuel vapors and open handling of fuel.
^ Risk of injury as a result of fuel splashing into eyes

CAUTION:
^ No fire, naked flame or smoking.
^ Avoid the creation of sparks.
^ Pour fuels only into the canisters provided for this purpose, and store in such canisters.
^ Wear protective gloves and, if necessary, eye protection when handling fuel.

2. Remove injection nozzle, refer to Powertrain Management.

CAUTION In the following steps, do not crank engine using ignition/starter switch but use the contact switch of the compression tester or an equivalent external starter switch, refer to Cranking Engine Using an External Starter Switch. Service and Repair

3. Crank engine with starter several times with the starter in order to eliminate combustion residues in the cylinder
4. Screw Compression tester (01) with connector (02) into the prechamber of the cylinder to be tested
5. Crank engine with starter using the external starter switch
6. Perform test procedure on the remaining cylinders in the same manner
7. Compare the measurements obtained with the permissible values
- Compression pressure:
New value: 29-35 bar
Wear limit: approx. 18 bar
Permissible difference between individual cylinders: max. 3 bar

NOTE: If minimum compression pressure is not achieved or if the permissible difference between individual cylinders is exceeded, test cylinders for leaks, refer to Cylinder Leakdown Testing. Testing and Inspection

8. Install in the reverse order