What was found
EN ROUTE FROM PHX TO PDX B-SYSTEM HYD OVERHEAT LIGHT ILLUMINATED, FOLLOWED CHECKLIST TO CLEAR DISCREPANCY, OVERHEAT LIGHT REMAINED ON, DIVERTED TO LAS. MAINTENANCE REMOVED AND REPLACED B-SYSTEM ELECTRIC MOTOR DRIVEN HYDRAULIC PUMP IAW R4M29002 (PUMP WAS BORROWED FROM UAL IN LAX TWO DAYS EARLIER). FLUSHED HYDRAULIC SYSTEM AND REPLACED FILTERS IAW BMM 29-15-00, LEAK AND OPERATIONAL CHECK WAS GOOD.