Anonymous-0
Well-known Member
I noticed a rattling sound when I started my Cat 931B with a 3204 engine. Upon inspection I found the water pump pulley loose and wobbling. The bolts holding the fan and pulley on were tight but the pulley had quite a bit of movement so I took the fan off and the big nut that holds the hub on the water pump shaft was loose. Not being able to hold the shaft so I could tighten the nut, I drained the coolant and took the water pump off. I scratched my knuckles up pretty good on the rad in the process. I used an electric impact wrench to tighten the nut and put everything back together. There is very, very slight play when the the fan is pushed back and forth but the pulley is much tighter. At idle the pulley has a very tiny bit of wobble but at higher rpms seems to run truer. The belt is lined up good and it's a heavy steel pulley. The water pump was replaced a few years ago and has less than 1500 hours on it. What would cause the nut to come loose and/or could the water pump bearing be going? It is a jobber water pump and doesn't leak. Has anyone else experienced the nut on the water pump coming loose? Any help would be appreciated. Thanks Dave
