Fault Phenomenon: Volvo L70 wheel loader hydraulic pump noisy, air bubbles in oil, actions jitter.

Troubleshooting Process:
– Checked suction line: O-ring seal at internal tank suction line flange aged and hardened.
– Checked flange: mounting bolts loose.
– Checked oil level: level normal.
– Checked lines: external lines no air leakage.

Root Cause: The O-ring seal on the suction line flange inside the hydraulic tank aged and lost elasticity, allowing air to be drawn into the pump during suction.

Required Parts: Replace suction line flange seal (requires tank cleaning).