CONFIDENTIAL TIBU3280-03

Some of the M300 Excavators may experience overfilling of the transmission housing. A possible source of the overfilling may be a leak between the down shift inhibitor valve (mounted on the rear of the transmission housing) and inhibitor valve cover. An improperly machined cover (a cover that is not flat) can be the cause of the leak.

Test the joint that is between the cover and the downshift inhibitor valve for leakage. Use the attached testing procedure in order to check for leakage of the downshift inhibitor valve. Refer to Illustration 1.

If no leak is detected in the following procedure, test the first and the second gear clutch seals for leakage. Use the procedure that is in the "Transmission Assembly Procedure" of the corresponding "Power Train D&A Manuals" for the testing of the clutch seals. When a clutch seal leak is detected, repair with the corresponding new seal.

Note: Refer to the Service Manual for the disassembly and assembly procedures.

Contact your Product Analyst and report the leak test results.

Required Parts if leaks are detected at "P1" or "P2" Ports

(B, K, and P2 plugged - Hand Pump on P1)

Refer to Illustrations 1 and 2.

1. Remove the hose assembly and fittings from Ports B and K in the Downshift Inhibitor Valve that is located on the rear of the transmission.
2. Plug Ports B and K with Tool D.
3. Remove the Hose Assemblies from Ports "P1" and "P2" in the Downshift Inhibitor Valve.
4. Plug Port P2. Install Tool C on the fitting of Port P2.
5. Connect the Hand Pump to Port P1. Perform the following steps:

1. Remove fittings from Port P1
2. Install Tool B in Port P1
3. Install Tool A onto Tool B

1. Apply 4000 kPa (580 psi) of pressure to Port P1 of the Downshift Inhibitor for a minimum of 7-minutes.

If the pressure gauge reading does not decrease (remains constant) for a period of 7-minutes, you have determined that there are no leaks in the P1 Circuit. Proceed to Step 7.

If the gauge pressure is not maintained (decreases) for a 7-minute period, the Downshift Inhibitor Valve is leaking. Replace with a new Downshift Inhibitor Valve. Refer to the Disassembly and Assembly Module of the M300 Series Excavator Machine Systems for instructions to remove and install the Downshift Inhibitor Valve in-chassis.

Note: The following could impair the accuracy of the above test.

1. a leaking gauge
2. a leaking valve in the hand pump
3. the presence of air in the hydraulic circuit

(B, K, P1 plugged - Hand Pump on P2)

Refer to Illustrations 2 and 3.

1. Using the same tools as above, plug Port P1. Connect Hand Pump to Port P2.
2. Apply 4000 kPa (580 psi) of pressure to Port P2 of the Downshift Inhibitor for a minimum of 7-minutes.

If the pressure gauge reading does not decrease (remains constant) for a period of 7-minutes, you have determined that the P2 Circuit does not leak.

If the gauge pressure is not maintained for a 7-minute period, the Downshift Inhibitor Valve is leaking. Replace the leaking valve with a new Downshift Inhibitor Valve. Refer to the Disassembly and Assembly Module of the M300 Series Excavator Machine Systems for instructions to remove and install the Downshift Inhibitor Valve in-chassis.

Note: The following could impair the accuracy of the above test.

1. a leaking gauge
2. a leaking valve in the hand pump
3. the presence of air in the hydraulic circuit

9. Remove Tools A, B, C, and D.

10. Install fittings and hose assemblies that were removed in Steps 1 and 3.

11. If leaks were not detected in the previous steps, test the first and second gear clutch seals. Use the procedure that is mentioned in the "Transmission Assembly Procedure" of the "Power Train Disassembly and Assembly Module" in order to test seal quality.

Illustration 1 Illustration 2

Illustration 3

(1) 1U-5230 Hand Pump, (2) 5S-2403 Fitting, (3) 1S-8937 Valve, (4) 2D-7325 Tee, (5) 6V-4143 Coupler Assembly, (6) 6V-3014 Hose Assembly, (7) 6V-4143 Coupler Assembly, (8) 8T-0855 Gauge, and (9) Nipple Assembly.

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