Pontiac FIREBIRD 1972 Service Manual page 1045

TURBO HYDRA-MATIC (M-38) TRANSMISSION 7G-7
b. Clutch plates burned (see BURNED CLUTCH
PLATES below).
b. Servo piston stuck or cocked
3. Intermediate Overrun Band
-
intermediate overrun
band broken or burned (look for cause), not engaged
or servo pin.
c. Inspect for proper number and type of clutch
plates.
4. Case
-
porosity*.
NO ENGINE BRAKING IN LO RANGE
ROUGH 1-2 SHIFT
(Install pressure gauge)
(Install pressure gauge)
1. Low Oil Pressure
-
pressure regulator and/or boost
valves stuck.
1. High Oil Pressure
-
refer to HIGH LINE PRES-
SURE above.
2. Manual Low Control Valve Assembly
-
stuck.
2. 1-2 Accumulator:
3. Low and Reverse Clutch
-
piston inner seal damaged
or missing.
a. Oil rings damaged.
b. Piston stuck.
c. Broken or missing spring.
NO PART THROTTLE DOWNSHIFT
(Install pressure gauge)
d. Bore damaged.
1. Oil Pressure
-
vacuum modulator assembly, modula-
tor valve or pressure regulator valve train (other mal-
functions may also be noticed).
3. Intermediate Clutch
-
check for burned and number
(type) of plates.
4. Case:
2. Detent Valve and Linkage
-
sticks, disconnected or
broken.
a. Check for correct number and location of check
balls.
3. 2-3 shift valve
-
stuck.
b. Porosity
*
between channels.
NO DETENT (WIDE-OPEN THROTTLE)
DOWNSHIFT
ROUGH 2-3 SHIFT
(Install pressure gauge)
1. Detent cable or retainer not adjusted properly.
1. High Oil Pressure
-
refer to HIGH LINE PRES-
SURE above.
2. Detent cable disconnected at transmission or throttle
linkage.
2. 2-3 Accumulator:
3. Valve Body:
a. Oil ring damaged.
b. Piston stuck.
c. Broken or missing spring.
d. Piston bore damaged.
a. Detent valve sticks.
b. Detent regulator valve sticks.
c. Incorrect spacer plate or gasket.
NO ENGINE BRAKING IN SUPER RANGE
HIGH OR LOW SHIFT POINTS
(Install pressure gauge)
(Install pressure gauge)
1. Low Oil Pressure
-
pressure regulator and/or boost
valve stuck.
1. Oil Pressure:
a. Engine Vacuum
-
check at transmission end of
modulator pipe.
2. Intermediate Servo and 2-3 Accumulator:
b. Check vacuum line connections at engine and
transmission.
a. Servo or accumulator oil rings or bores leaking or
damaged.