GMC 1976 ZEO 6083 Maintenance Manual page 461

PRELIMINARY CHECKING PROCEDURE
CHECK TRANS OIL LEVEL
CHECK OUTSIDE MANUAL LINKAGE AND CORRECT
CHECK ENGINE TUNE
INSTALL OIL PRESSURE GAGE
CONNECT VACUUM GAGE WITH "T" FITTING INTO MODULATOR LINE
& TACHOMETER TO ENGINE .
Preliminary Checking Procedure
TRANSMISSION 7- 13
CAUTION: TOTAL RUNNING
TIME FOR THIS COMBINATION
NOT TO EXCEED 2 MINUTES .
*THE DRIVE-30 MPH CLOSED THROTTLE PRESSURE READING MAY BE TAKEN DURING A
ROAD TEST OR :
1 . VEHICLE ON HOIST-DRIVING WHEELS OFF GROUND, FOOT OFF BRAKE, IN DRIVE
RANGE .
2 . Engine 2000 RPM.
3 . CLOSE THROTTLE (FOOT
ENGINE 2000-1200 RPM.
OFF ACCELERATOR) AND TAKE
PRESSURE READING
NOTE : WITH CLOSED THROTTLE AND DRIVING WHEELS OFF THE GROUND, ENGINE RPM
WILL DROP RAPIDLY . PRESSURE READING MUST BE TAKEN WITHIN RPM'S INDICATED
AND WITH CLOSED THROTTLE .
CHECK OIL PRESSURES IN FOLLOWING MANNER
RANGE OIL PRESSURE
NORMAL P.S .I.
DRIVE-BRAKES APPLIED
ENGINE AT 1000 RPM
60 TO 90
SUPER OR LO-BRAKES APPLIED
ENGINE AT 1000 RPM
135 TO 160
REVERSE-BRAKES APPLIED
95 TO 150
ENGINE AT 1000 RPM
NEUTRAL-BRAKES APPLIED
ENGINE AT 1000 RPM
55 TO 70
DRIVE IDLE
SET ENGINE IDLE TO
60 TO 85
SPECIFICATIONS
DRIVE-30 MPH
CLOSED THROTTLE OR ON HOIST*
55 TO 70