System Pressure And Stall Speed, Check

System pressure and stall speed, check

Special tools:
999 2531 MANOMETER 999 2531 Manometer
999 5074 NIPPLE 999 5074 NIPPLE

Oil level, check
See Checking oil level, AW50-42 Checking Oil Level.

Manometer, connection




Remove the air cleaner.
Remove the test plug from the transmission and fit nipple 999 5074 NIPPLE 999 5074 NIPPLE.
Connect the hose and manometer 999 2531 MANOMETER 999 2531 Manometer to the nipple.
Temporarily install the air cleaner during the check.

Idle speed, check
Start the engine and allow it to idle with the selector lever in position N.
Check idle speed. See table in System pressure, check.

System pressure, check
Depress the brake pedal.
Move the selective levers to the various gears and read off system pressure.






Stall speed and system pressure
Check stall speed in conjunction with a system pressure check.
The stall speed check primarily provides information on the condition of the torque converter, transmission clutches and the engine.
The following is necessary to ensure correct test results:
- The engine provides full output
- System pressure is correct
- The transmission has the correct fluid level and operating temperature.

Note! Never check stall speed if system pressure is low.

Check
Air conditioning (AC) should be off. Place chocks behind all four wheels. Start the engine.

Caution! Apply the handbrake and depress the brake pedal hard with your left foot during the check.

Move the selector lever to D, apply full throttle max 5 seconds and read off the highest rpm as well as system pressure. Compare with the table below.

Note! The stall speed check must not last more than 5 seconds.





Repeat the check with the gear selector in R.
Compare with the table.
If the speed exceeds the table values, see High stall speed; if speed is below the table values, see Low stall speed.

High stall speed
The above conditions Stall speed and system pressure are fulfilled. Is the acceleration time for 0-100 km/h normal?
If the actual stall speed exceeds the normal value by more than 300 rpm:
- Check if the oil is discoloured or has a foul odor. See Oil, quality check, AW50-42 Oil, Quality Check.
If the oil is OK, replace the torque converter. See Replacing torque converter/oil pump sealing ring, AW50-42 Replacing Torque Converter/Oil Pump Sealing Ring for the procedure for torque converter replacement.
Dirty oil indicates worn or burnt clutch discs; replace the transmission as described in Replacing the transmission, AW50-42 Replacing Transmission.
Recheck stall speed after transmission replacement.

Low stall speed




The above conditions Stall speed and system pressure are fulfilled.
If the actual stall speed exceeds the normal value by more than 300 rpm:
Try a new torque converter. See Replacing torque converter/oil pump sealing ring, AW50-42 Replacing Torque Converter/Oil Pump Sealing Ring for the procedure for torque converter replacement.
Recheck stall speed after torque converter replacement. If the fault remains, replace the transmission. See Replacing the transmission, AW50-42 Replacing Transmission.
If there is noise in the transmission:
Replace the transmission. See Replacing the transmission, AW50-42 Replacing Transmission.
Recheck stall speed after transmission replacement.