Usage:
12G ( 61M12027-Up, 3WC1067-Up ),
120G ( 87V8360-Up, 11W1251-Up ),
130G ( 74V2321-Up, 12W1082-Up ),
140G ( 5MD1-Up, 72V10334-Up, 13W741-Up ),
16G ( 93U2679-Up ),
160G ( 4JD141-Up ) Motor Graders;
426 ( 7BC1-Up );
436 ( 5KF1-Up );
438 ( 3DJ1-Up ) Backhoe Loaders
The bias piston in the hydraulic pump head can come loose and back completely out. With the bias piston backed out, the swashplate is at the maximum angle which causes the pump to deliver maximum oil flow through the relief valve. This causes the oil to overheat in a short time. This affects machine performance and causes the temperature alarm to sound.
Rework Procedures
Remove the hydraulic pump head and perform the following steps on the bias piston and the control piston.
1. Remove the bias piston and control piston from the pump head.
2. Thoroughly clean the threads in the pump head and pistons. Use the appropriate thread chaser to cleanup any damaged threads.
NOTE: Some of the pistons have M22/1.5 threads and others have 7/8"-14 threads. The torque requirement is the same for either thread size.
3. Apply 9S3263 Thread Lock to the piston threads after using 6V1541 Primer to remove the oil from the threads.
4. Install the pistons in the pump head and tighten the pistons to a torque of 79 ± 4 N·m (58 ± 3 lb ft).
Location of piston.