No question here, just an anecdote about a water pump in my 86 740 sedan. Nobody at my house cares, but I thought you might get a kick out of it.

The water pump has been bad for more than a year, maybe two. It used to make a little noise, and over the last half year it has made a lot of noise. Since I knew what it was and it wasn't leaking, I didn't pay it much attention. I suppose I'm taking "if it ain't broke don't fix it" to the next level: "If it still drives it ain't broke".

It finally start to leak. It would lose about a quart of water in three weeks of my typical use. I had not actually looked at it with the engine running until last week. The water pump pulley was jumping around so much I couldn't believe the belt was staying on. I replaced the pump yesterday.

There is some 1/4 inch of play at the impellor end. The impellor has been running against and has cut into the housing. The impellor blades have wiorn down from rubbing against the housing. I presume the water pump has a pair of ball bearings on the shaft, an inner and outer. I am guessing the inner bearing has lost all the balls and is running race-on-race. The outer bearing (closest to pully) seems to be more or less okay.

This thing was beyond shot, and still it remained in service as a daily driver. Last weekend it made a 5 hour round trip at freeway speeds like this.
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-rcf