Fault Phenomenon: Foton Raysta L14 steering is normal when cold. After continuous steering operations (operating temperature), steering becomes heavy, power assist is intermittent, and eventually fails.

Troubleshooting Process:
– Checked power steering fluid reservoir level: level normal, no foam.
– Checked steering pump belt: belt not slipping, tension normal.
– Checked steering gear internally: no sticking, mechanical connection normal.
– Measured steering pump outlet pressure at operating temperature: found pressure drops significantly as oil temperature rises.

Root Cause: Internal vanes of the steering pump are worn, causing severe internal leakage under thermal conditions.

Required Parts: Power steering pump assembly.