Cherokee 4WD L6-4.0L VIN S (1998)
Torque Converter: Component Tests and General Diagnostics
TORQUE CONVERTER STALL TEST
Stall testing checks the holding ability of the transmission clutches and brakes and of the torque converter stator overrunning clutch. Stall speeds
are checked in both Drive and Reverse ranges with the AW-4 transmission.
1. Before starting test, be sure fluid level is correct and fluid is at normal operating temperature.
2. Connect tachometer to engine. Position tachometer so it can be viewed from drivers seat.
3. Apply parking brakes and block wheels.
4. Apply and hold service brakes.
5. Shift transfer case into 2H position.
6. Start engine.
WARNING: DO NOT ALLOW ANYONE TO STAND AT THE FRONT OR REAR OF THE VEHICLE DURING THE TEST.
7. Shift transmission into D range.
8. Open throttle completely and record maximum engine rpm registered on tachometer. It takes anywhere from 4 to 10 seconds to reach maximum
rpm. However, once maximum rpm has been achieved, do not hold wide open throttle for more than 3-4 seconds.
CAUTION: Stalling the converter causes a rapid increase in fluid temperature. To avoid fluid overheating, hold wide open throttle for no more
than 4 seconds after reaching peak rpm. In addition, if more than one stall test is required, run the engine at 1000 rpm with the transmission in
Neutral for at least 20 seconds to cool the fluid.
9. Stall speed should be in 2100 - 2400 rpm range in Drive.
10. Release throttle, shift transmission into Neutral, and run engine for 20-30 seconds to cool fluid.
11. Shift transmission into Reverse.
12. Repeat stall test.
13. Stall speed in Reverse should also be in 2100-2400 rpm range.
14. Release accelerator pedal, shift transmission into Neutral, and run engine for 20-30 seconds to cool fluid.
STALL SPEED TEST ANALYSIS
If engine rpm is lower than specified in D and Reverse, check for the following:
-
engine output/performance insufficient
-
stator overrunning clutch in torque converter not holding if engine speed was 1500 rpm or less.
If stall speed in D range is higher than specified, check for the following:
-
line pressure low
-
forward clutch slipping
-
No. 2 one-way clutch not holding
-
overdrive one-way clutch not holding
If stall speed in Reverse was higher than specified, check for the following:
-
line pressure low
-
direct clutch slipping
-
first/reverse brake slipping
-
overdrive one-way clutch not holding
If stall speeds were higher than specified in both D and Reverse, check for the following:
-
low fluid level
-
line pressure low
-
overdrive one-way clutch not holding
