Jeep Wrangler 1997 Manual - page 991
(7) If a second stall test is required, cool down
fluid before proceeding. Shift into NEUTRAL and run
engine at 1000 rpm for 20-30 seconds to cool fluid.
STALL TEST ANALYSIS
Stall Speed Too High
If the stall speed exceeds 2500 rpm, transmission
clutch slippage is indicated.
Stall Speed Low
Low stall speed with a properly tuned engine indi-
cate a torque converter overrunning clutch problem.
The condition should be confirmed by road testing. A
stall speed 250-350 rpm below normal indicates the
converter overrunning clutch is slipping. The vehicle
also exhibits poor acceleration but operates normally
once highway cruise speeds are reached. Torque con-
verter replacement will be necessary.
Stall Speed Normal But Acceleration Poor
If stall speeds are normal (1800-2300 rpm) but
abnormal throttle opening is required for accelera-
tion, or to maintain cruise speed, the converter over-
running clutch is seized. The torque converter will
have to be replaced.
Converter Noise During Test
A whining noise caused by fluid flow is normal dur-
ing a stall test. However, loud metallic noises indi-
cate a damaged converter. To confirm that the noise
is originating from the converter, operate the vehicle
at light throttle in DRIVE and NEUTRAL on a hoist
and listen for noise coming from the converter hous-
ing.
AIR TESTING TRANSMISSION CLUTCH AND BAND
OPERATION
Air-pressure testing can be used to check transmis-
sion front/rear clutch and band operation. The test
can be conducted with the transmission either in the
vehicle or on the work bench, as a final check, after
overhaul.
Air-pressure testing requires that the oil pan and
valve body be removed from the transmission. The
servo and clutch apply passages are shown (Fig. 10).
Front Clutch Air Test
Place one or two fingers on the clutch housing and
apply air pressure through front clutch apply pas-
sage. Piston movement can be felt and a soft thump
heard as the clutch applies.
Rear Clutch Air Test
Place one or two fingers on the clutch housing and
apply air pressure through rear clutch apply passage.
Piston movement can be felt and a soft thump heard
as the clutch applies.
Front Servo Apply Air Test
Apply air pressure to the front servo apply pas-
sage. The servo rod should extend and cause the
band to tighten around the drum. Spring pressure
should release the servo when air pressure is
removed.
Rear Servo Air Test
Apply air pressure to the rear servo apply passage.
The servo rod should extend and cause the band to
tighten around the drum. Spring pressure should
release the servo when air pressure is removed.
CONVERTER HOUSING FLUID LEAK DIAGNOSIS
When diagnosing converter housing fluid leaks,
two items must be established before repair.
(1) Verify that a leak condition actually exists.
(2) Determined the true source of the leak.
Some suspected converter housing fluid leaks may
not be leaks at all. They may only be the result of
residual fluid in the converter housing, or excess
fluid spilled during factory fill or fill after repair.
Converter
housing
leaks
have
several
potential
sources. Through careful observation, a leak source
can be identified before removing the transmission
for repair. Pump seal leaks tend to move along the
drive hub and onto the rear of the converter. Pump
O-ring or pump body leaks follow the same path as a
seal leak (Fig. 11). Pump vent or pump attaching bolt
leaks are generally deposited on the inside of the
Fig. 10 Air Pressure Test Passages
TJ
TRANSMISSION AND TRANSFER CASE
21 - 85
DIAGNOSIS AND TESTING (Continued)