Sunday I took the XJ8 out to wash the car. Turning left at a corner I noticed the power steering was sluggish and the battery light came on. I thought the car had died, but no it kept running, so I continued to the car wash. Got thru the car wash then on the way home other lights came on, ABS etc, that is when I noticed the white smoke out the back of the car. Limped home and popped the hood. Water all over the engine and draining from the bottom of the car. I did not want to chance driving the car again so I called for a tow truck the following day.
The mechanic identified the problem as the water pump bearing had failed causing the water pump to leak. The car has 104,900 miles on it so I wasn't surprised. What did concern me was there was no warning of the bearing going out or any water leakage. The mechanic showed me the old pump and I heard the noise from the pump. Now I am concerned about the thermostat, he did not change it. He said there was no leakage from the part.
Is this unusually for the pump to go out without any warning? Should I have the thermostat replaced? Car runs fine now and no warning lights. The car was not drivable with a leaking water pump.

 

Over my many years of many car ownership I have never had a water pump fail in such a dramatic and sudden fashion. It usually starts with a a weep from the shaft that progressively gets worse. At that point the pump gets replaced.

I never replace a water pump w/o replacing the thermostat. And, depending on the age of the hoses, I generally replace all the cooling rubber as a safe measure.