Hydraulic Pressure Tests

Hydraulic test pressures range from a low of one psi (6.895 kPa) governor pressure, to 300 psi (2068 kPa) at the rear servo pressure port in reverse.
An accurate tachometer and two test gauges are required for the pressure test. Test Gauge C-3292 has a 100 psi range and is used at the accumulator, governor, and front servo pressure ports. Test Gauge C-3293-SP has a 300 psi range and is used at the rear servo port and overdrive test ports where pressures are higher. In cases where two test gauges are required, the 300 psi gauge can be used at any of the other test ports.

Pressure Test Port Locations

Fig. 6:

Fig. 7:

Fig. 8:

Pressure test ports locations are provided at the accumulator, front servo, and rear servo, governor passage, and overdrive clutch pressure passage (Fig. 6), (Fig. 7) and (Fig. 8).
Line pressure is checked at the accumulator port on the right side of the case. The front servo pressure port is at the right side of the case just behind the filler tube opening.
Connect a tachometer to the engine. Position the tachometer so it can be observed from under the vehicle. Raise the vehicle on a hoist that will allow the wheels to rotate freely.

PRESSURE TEST PROCEDURE
Test One - Transmission In 1 Range
This test checks pump output, pressure regulation, and condition of the rear clutch and servo circuit. Test Gauges C-3292 and C-3293-SP are required for this test. Gauge C-3292 has a 100 psi range. Gauge C-3293-SP has a 300 psi range.
1. Connect 100 psi Gauge C-3292 to accumulator port.

Fig. 6:

Fig. 7:

2. Connect 300 psi Gauge C-3293-SP to rear servo port (Fig. 6) and (Fig. 7).
3. Disconnect throttle and gearshift rods from manual and throttle levers.
4. Start and run engine at 1000 rpm.
5. Move shift lever (on manual lever shaft) all the way forward into 1 range.
6. Move transmission throttle lever from full forward to full rearward position and note pressures on both gauges.
7. Line pressure at accumulator port should be 54 - 60 psi (372 - 414 kPa) with throttle lever forward and gradually increase to 90 - 96 psi (621 - 662 kPa) as lever is moved rearward.
8. Rear servo pressure should be same as line pressure within 3 psi (20.68 kPa).

Test Two - Transmission In 2 Range
This test checks pump output and pressure regulation. Use 100 psi Test Gauge C-3292 for this test.

Fig. 6:

Fig. 7:

1. Connect test gauge to accumulator pressure port (Fig. 6) and (Fig. 7).
2. Start and run engine at 1000 rpm.
3. Move shift lever on valve body manual lever shaft, one detent rearward from full forward position. This is 2 range.
4. Move transmission throttle lever from full forward to full rearward position and read pressure at both gauges.
5. Line pressure should be 54 - 60 psi (372 - 414 kPa) with throttle lever forward and gradually increase to 90 - 96 psi (621 - 662 kPa) as lever is moved rearward.

Test Three-Transmission In D Range
This test checks pressure regulation and condition of the clutch circuits. Use both pressure Test, Gauges C-3292 and C-3293-SP for this test.

Fig. 6:

Fig. 7:

1. Connect test gauges to accumulator and front servo ports (Fig. 6) and (Fig. 7). Use either test gauge at the two ports.
2. Start and run engine at 1600 rpm for this test.
3. Move selector lever to D range. This is two detents rearward from full forward position.
4. Read pressures on both gauges as transmission throttle lever is moved from full forward to full rearward position.
5. Line pressure should be 54 - 60 psi (372 - 414 kPa) with throttle lever forward and gradually increase as lever is moved rearward.
6. Front servo is pressurized only in D range and should be same as line pressure within 3 psi (21 kPa) up to downshift point.

Test Four-Transmission In Reverse
This test checks pump output, pressure regulation and the front clutch and rear servo circuits. Use 300 psi Test Gauge C-3293-SP for this test.

Fig. 6:

Fig. 7:

1. Connect 300 psi gauge to rear servo port (Fig. 6) and (Fig. 7).
2. Start and run engine at 1600 rpm for test.
3. Move valve body selector lever four detents rearward from the full forward position. This is Reverse range.
4. Move throttle lever all way forward then all way rearward and note gauge readings.
5. Pressure should be 145 - 175 psi (1000 - 1207 kPa) with lever forward and increase to 230 - 280 psi (1586 - 1931 kPa) as lever is moved rearward.

Test Five-Governor Pressure
This test checks governor operation by measuring governor pressure response to changes in engine speed. It is usually not necessary to check governor operation unless shift speeds are incorrect or if the transmission will not downshift.

Fig. 6:

Fig. 7:

1. Connect 100 psi Test Gauge C-3292 to governor pressure port (Fig. 6) and (Fig. 7).
2. Move shift lever to D range.
3. Start and run engine at curb idle speed and note pressure. At idle and with vehicle stopped, pressure should be zero to 1.5 psi maximum. If pressure exceeds this figure, governor valve or weights are sticking open.
4. Slowly increase engine speed and observe speedometer and pressure test gauge. Governor pressure should increase in proportion to vehicle speed.
5. Pressure rise should be smooth and drop back to 0 to 1.5 psi when wheels stop rotating.

Fig. 9:

6. Compare results of pressure tests with analysis charts (Fig. 9).