Measuring and Adjusting Pressure Values

Measuring and Adjusting Pressure Values







Vacuum unit (1)
The vacuum line should be detached at the vacuum unit for measuring the modulating and working pressure (step 1).

Test connection for working pressure (A)
Connect pressure gauge with range up to 25 bar.

Test connection for modulating pressure (M)
Connect pressure gauge with range up to 10 bar.

Test connection for governor pressure (R)
Use pressure gauge as for modulating pressure.

Special Tool:

Note:
To measure working pressure, modulating pressure and governor pressure, run the pressure hoses through the window to the righthand driver's door and clamp tight by winding up the window. Pressure hoses must not sag or be touching the exhaust pipe.






Attention:
When performing any adjusting work on the vehicle when the engine is running, the parking brake must be applied and the selector lever be in position "P".

When performing measurements with the vehicle stationary and the Drive position engaged, the service brake must be applied in addition to the parking brake.

After the test, run the engine and check measurement points for leaks.


Measuring modulating pressure

1. Detach vacuum line (10) at the vacuum unit (60).

2. Drive car in selector lever position "D" at approx. 50 km/h and take the pressure reading






Adjusting modulating pressure






3. Remove rubber cap on the vacuum unit (60).

4. Pull locking plate (2) out of the locking slots far enough to allow it to be turned.

5. The adjusting screw in the vacuum unit can now be turned with the locking plate. One turn of the adjusting screw produces a pressure change of approx. 0.4 bar.

6. After turning the adjusting screw press the locking plate into the locking slots again.

7. Re-fit rubber cap to the vacuum unit.

8. Measure modulating pressure once again.

9. Fit on vacuum line.

Measuring working pressure

10. Detach vacuum line of the vacuum unit.

11. Start engine and run at approx. 1000 rpm, take pressure reading with drive position "D" engaged.

Note:
The working pressure cannot be adjusted. The measurement only provides indications regarding operation of the working pressure control valve in the control valve body. If the working pressure is measured, it is important to ensure that the modulating pressure is exactly set.

Measuring governor pressure

Drive car on the chassis dynamometer or on the road at the speeds indicated in the table and take the pressure readings. If no governor pressure is indicated, remove centrifugal governor and clean.

If the total pressure readings differ from the figures stated in the tables, the centrifugal governor must be renewed.

Instruction for cars with catalytic converter
On cars with transmission shift point retard, the pressure oil line must be unscrewed at the test connection for the governor pressure (MR).

Installation instruction






Slacken bracket for the switchover valve (Y3/2) at the transmission housing. Unscrew oil line (O) at the centrifugal governor cover and pressure oil line at the governor pressure test connection (MR).

Fit on hollow bolts with new aluminium seals. Fist of all, tighten pressure oil line (MR), then tighten oil line (O) and bracket for the switchover valve.