Dodge D150 1990 Service Manual page 905

21 - 54 AUTOMATIC TRANSMISSION
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t i g h t e n a r o u n d the d r u m . S p r i n g tension should r e -
lease the servo w h e n a i r pressure is removed.
Rear Servo Test
A p p l y a i r pressure t o t h e rear servo apply passage.
The servo rod should extend a n d cause t h e band t o
t i g h t e n around the d r u m . S p r i n g tension should r e -
lease the servo w h e n a i r pressure is removed.
CONVERTER HOUSING FLUID LEAK DIAGNOSIS
W h e n diagnosing converter h o u s i n g fluid leaks,
t w o items m u s t be established before repair. F i r s t , i t
m u s t be verified t h a t a leak condition a c t u a l l y exists.
A n d second, t h e t r u e source o f t h e leak m u s t be de-
termined.
Some suspected converter h o u s i n g fluid leaks m a y
not be leaks a t a l l . They m a y only be t h e r e s u l t o f
residual fluid i n t h e converter housing, o r excess
fluid spilled d u r i n g factory fill or r e f i l l after repair.
Converter h o u s i n g leaks have several p o t e n t i a l
sources. T h r o u g h careful observation, a leak source
can be identified before r e m o v i n g t h e transmission
for repair.
Pump seal leaks t e n d t o move along t h e d r i v e h u b
and onto the rear o f t h e converter. P u m p O-ring or
p u m p body leaks follow the same p a t h as a seal leak
(Fig. 6).
Pump vent or p u m p a t t a c h i n g b o l t leaks are gener-
a l l y deposited on the inside o f t h e converter housing
and not on t h e converter i t s e l f (Fig. 6).
Pump seal or gasket leaks u s u a l l y t r a v e l down the
inside of t h e converter housing.
F r o n t band lever p i n p l u g leaks are generally de-
posited on t h e housing and not on the converter.
PUMP PUMP PUMP
Fig. 6 Converter Housing Leak Paths
LEAK DIAGNOSIS PROCEDURE
(1) Raise the rear o f the vehicle and a l l o w accumu-
lated fluid t o d r a i n o u t o f the converter housing.
(2) Check and adjust the t r a n s m i s s i o n fluid level.
(3) Raise t h e vehicle. Remove t h e converter hous-
i n g dust cover a n d wipe as m u c h fluid as possible
from the converter housing.
(4) Fabricate a test probe (Fig. 7). T h e n attach t h e
probe t o t h e converter housing w i t h one o f the dust
shield bolts (Fig. 7).
(5) Have a helper r u n the engine a t 2500 r p m ( w i t h
the transmission i n N e u t r a l ) for t w o m i n u t e s ; t h e n
stop the engine.
(6) Inspect t h e test probe and converter housing. I f
a leak is evident, note the color o f the fluid. Trans-
mission fluid i s red. E n g i n e o i l ranges i n color from
b r o w n t o green, or t o black w h e n t h e o i l is d i r t y .
(7) I f t h e probe upper surface i s dry, the converter
and seal are not a t f a u l t . A p a t h o f fluid across t h e
probe upper surface indicates a converter or seal
leak. F l u i d l e a k i n g under the probe is coming f r o m
the p u m p housing area (Fig. 8).
(8) F l u i d l e a k i n g under t h e probe could be f r o m
the: p u m p seal and/or bushing, p u m p vent, k i c k d o w n
lever shaft access p l u g , pump bolts, or porous spots
i n the p u m p body or transmission case (Fig. 8).
(9) I f porous spots i n the transmission case or p u m p
body are t h e suspected leak source, pressurize t h e
transmission as described i n L e a k Testing W i t h A i r
Pressure.
S H I E L D MATERI A L: 5-1/2" X 1-1/2" X 1/32"
B O L T S H E E T M E T A L RN778
Fig. 7 Leak Test Probe
TORQUE CONVERTER LEAK POINTS
Possible sources o f converter leaks are:
(a) Leaks a t t h e weld j o i n t around the outside
diameter w e l d (Fig. 9).
(b) Leaks a t t h e converter h u b weld (Fig. 9).
LEAK TESTING WITH AIR PRESSURE
This test involves closing o f f t h e transmission
openings and pressurizing the transmission to 8 psi
w i t h a i r p u m p tool C-4080.
A soapy water s o l u t i o n is applied to suspected leak
points before and d u r i n g the pressure test. Leaks w i l l
be indicated b y t h e presence o f a i r bubbles coming
t h r o u g h the solution.