Testing cylinders for leaks - RA01001040150X(01-0150)
WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.
Preceding work:
Warning instructions when hood open (01-0085) .
Air cleaner removed (REMOVING AND INSTALLING AIR CLEANER - AR09.10-P-1050D )
Operation no. of operation texts and work units or standard texts and flat rates:
| Engine | warm up to normal operating temperature. |
| Ground cable at battery | disconnect, connect, encode radio, model 140 normalize power windows. |
| Spark plugs | remove, install (REPLACE SPARK PLUGS ). |
| Cap (1) on expansion reservoir (2) | open, leave open, close. |
| Coolant level | adjust to correct level (20-0100) . |
| Oil filler cap (3) | take off, fit on. |
| Cylinder leak tester (5) | connect to compressed air system. |
| Tester (5) | calibrate. |
| Connection hose (5a) | screw into first spark plug hole. |
| Piston of cylinder to be tested | rotate at crankshaft with setting device to ignition TDC (01-0120) .
NOTE:
See table for pistons in TDC.
|
| Connection hose (5a) | connect to tester (5). |
| Compression chamber | pressurize (approx. 5 bar). When doing this, do not rotate the crankshaft; if necessary, lock crankshaft in position to prevent it turning (03-5000) . |
| Throttle valve | open by hand. |
| Pressure loss at tester (5) (in %) | read off. Determine whether the pressure escapes through intake manifold, exhaust, oil filler opening, spark plug hole of adjacent cylinder or through coolant opening. |
| All cylinders | test in firing order (1-5-3-6-2-4). |
DATA
| Total pressure loss | max. 25 % |
| At valves and cylinder head gasket | max. 10 % |
| At pistons and piston rings | max. 20 % |
PISTON AT TDC WITH MARKING INDEX ON VIBRATION DAMPER
| Marking | TDC | b=120° | a=240° |
|---|---|---|---|
| Piston at TDC of cylinder | 1 and 6 | 2 and 4 | 3 and 5 |
COMMERCIALLY AVAILABLE TOOL
| Cylinder leak tester | e.g. | Bosch, EFAW 210A Sun, CLT 228 |
NOTE:
After spraying oil onto the piston crown, it is possible to determine whether the leak exists at the piston rings or at the valves, or at the cylinder head gasket.