Fault Phenomenon: CAT rotary drilling rig instrument displays low engine oil pressure alarm, engine makes abnormal noise.

Troubleshooting Process:
– Checked oil level: oil level too low.
– Checked oil pump: pump gears worn, excessive clearance.
– Checked filter: oil filter clogged and bypass valve stuck.
– Checked bearings: main bearing clearance too large.

Root Cause: The oil pump is severely worn, unable to build sufficient oil pressure, or the main bearing clearance is too large causing excessive leakage.

Required Parts: Oil pump assembly or engine overhaul.