Repair Shantui Bulldozer-The heat engine can’t walk.During operation, the cold machine functioned normally for bulldozing tasks. However, after approximately 50 minutes of use, the bulldozer’s performance deteriorated, with a noticeable decrease in power as the oil temperature rose. Eventually, it became challenging to operate the machine even without a load.Allowing the machine to rest for two hours and restarting the engine after the oil temperature decreases restores both the starting and bulldozing functions to their normal state.

Throughout the operation, the engine throttle and speed remained constant, suggesting that the bulldozer’s diminished performance was not related to the engine itself. Initial assessments indicate that the issue may stem from insufficient oil in the bulldozer’s torque converter, a blockage in the oil circuit, or a malfunction in the transmission or steering clutch.

The inspection of the torque converter revealed persistent bubbles in the discharged oil after loosening the vent screw on the variable speed fine filter. These bubbles could not be expelled for a prolonged period. This indicates that if air ingress exists, venting both the cooler and warmer components would restore normal machine operation in cold conditions. The low-pressure oil circuit functions correctly, but air intake in the high-pressure oil circuit of the heat engine likely prevents the machine from moving. This issue may result from excessive vacuum in the low-pressure oil circuit.