Fault Phenomenon: Shantui DH80 steering is quiet when cold. When turning in place (operating temperature), the power steering pump whines, steering becomes heavy, and eventually fails.

Troubleshooting Process:
– Checked power steering fluid: level normal, no foam.
– Checked belt: belt not slipping.
– Checked reservoir strainer: strainer clean.
– Measured pump inlet vacuum at operating temperature: found excessive vacuum.

Root Cause: Wear of the power steering pump vanes causes internal leakage and cavitation noise at high temperatures.

Required Parts: Power steering pump assembly.