A de-superheating boiler feed water pump was facing high vibration issue for last 19 years. Pump had been overhauled multiple times in past, but the issue was not resolved. Dominant frequency appearing in vibration spectrum was 1.58 X order, which was not matching with any of the pump component frequency. Furthermore, maintenance history of the pump prior to year 2005 & complete machine manual was not available. Detailed study was conducted to resolve the high vibration issue of the pump, major cause of the problem was identified to be the increased wear ring clearance.