Air Pressure Tests
OVERVIEWFig. 4:
A no drive condition might exist even with correct fluid pressure, because of inoperative clutches or bands. The inoperative units, clutches, bands, and servos can be located through a series of tests. This is done by substituting air pressure for fluid pressure (Fig. 4).
The front and rear clutches, kickdown servo, and low-reverse servo may be tested by applying air pressure to their respective passages. To make air pressure tests, proceed as follows:
NOTE: Compressed air supply must be free of all dirt or moisture. Use a pressure of 30 psi.
Remove oil pan and valve body. Refer to Valve Body for removal procedure.
FRONT CLUTCH
Apply air pressure to front clutch apply passage and listen for a dull thud which indicates that front clutch is operating. Hold air pressure on for a few seconds and inspect system for excessive oil leaks.
REAR CLUTCH
Apply air pressure to rear clutch apply passage and listen for a dull thud which indicates that rear clutch is operating. Also inspect for excessive oil leaks. If a dull thud cannot be heard in the clutches, place finger tips on clutch housing and again apply air pressure. Movement of piston can be felt as the clutch is applied.
KICKDOWN SERVO(FRONT)
Direct air pressure into KICKDOWN SERVO ON passage. Operation of servo is indicated by a tightening of front band. Spring tension on servo piston should release the band.
LOW AND REVERSE SERVO(REAR)
Direct air pressure into LOW-REVERSE SERVO APPLY passage. Operation of servo is indicated by a tightening of rear band. Spring tension on servo piston should release the band.
If clutches and servos operate properly, no upshift indicates that a malfunction exists in the valve body.