water pump play

[tenn.jerry]

hello. i was out playing with my truck this evening and i noticed something odd. i had a friend start it up and rev theengine a little and when he did i saw the front of the water pump fan and all move forward toward the radiator. ive been reading the treads not having much luck finding anything on that back and forth movement.is my water pump wore out? do i need to replace it? whats your thoughts? any input will be appreciated and thanks in advance.

[JBNeal]

I reckon that water pump shaft would have some end play, but that endplay would be measured in thousandths. A loose water pump shaft has been known to get the fan out of balance, eventually causing a vibrations in the fan blades that will cause the blade metal to tear near the mounting bolts. This could cause the blades to fly apart during operation, tearing up sheet metal and the radiator from the shrapnel. I learned this lesson while on a school trip when our advisor's Suburban's exploding fan left us stranded 30 miles from the nearest town, 15 years before cell phone's were in everybody's hands.

[TodFitch]

The Plymouth service manual for that era calls for 0.0005" to 0.005" end play with 0.003" preferred. I believe the trucks side would have the same pump and thus the same specifications. Sounds like either the pump was not (re)built properly or has wear.