Air Pressure Tests
AIR PRESSURE CHECKSNOTE: Inoperative clutches or bands can cause a No Drive condition when fluid pressure is correct. The malfunctioning components can be located by a series of checks using air pressure instead of fluid pressure. To make these checks, proceed as follows:
1. Remove the main control cover and the valve body assembly.
2. Obtain the following parts and tools adapter plate part No. T82P-7006-C or equivalent; Adapter plate attaching screws part No. T82P-7006-C or equivalent; Air nozzle tool No. TOOL-7000-DE or equivalent; Air nozzle rubber tip TOOL-7000-DD or equivalent
3. Position adapter plate and gasket on the transaxle.
4. Install adapter plate attaching screws and torque to 7-8 ft lb. Note that each passage is identified on the plate.
Air Pressure Check Plate:
5. Using air nozzle equipped with rubber tip apply air pressure to each passage shown in the Air Pressure Check Plate image, in the following order:
a. Apply air pressure to the servo supply passage in service tool plate. Band should apply. Because of the cushioning effect of the servo release spring, the application of the band may not be heard or felt. Servo should hold air pressure without leakage and a dull thud should be heard when air pressure is removed allowing servo piston to return to the released position.
b. Apply air pressure to the forward clutch apply passage in the service tool plate. A dull thud should be heard or movement of the piston felt on the case as the clutch piston is applied. If clutch seals are leaking, a hissing sound will be heard.
c. Apply air pressure to intermediate clutch apply passage in service tool plate. A dull thud should be heard or movement of piston felt on the case as the clutch piston is applied. If clutch seals are leaking, a hissing sound will be heard.
d. Apply air pressure to reverse clutch apply passage in service tool plate. A dull thud should be heard or movement of piston felt on case as clutch piston is applied. If clutch seals are leaking, a hissing sound will be heard.
e. Apply air pressure to converter in passage in the service tool plate. This passage can only be checked for blockage. If passage holds air pressure, remove service tool plate and check for an obstruction or damage.
f. Remove governor cover. While applying air pressure to the passage in the service tool plate, watch movement of the governor valve.
g. Apply air pressure to control pressure-to-governor passage in the service tool plate. This passage can only be checked for blockage. If passage holds air pressure, remove service tool plate and check for an obstruction or damage.
6. The malfunctioning units can be located by applying air pressure to the adapter transmission case passages shown in the Air Pressure Check Plate image.
CAUTION: Use dry, filtered air regulated to 25 psi.