Greetings, Scotty. I have an 02 Jaguar X-Type 3.0 Sport, MT with about 54K miles that has developed a serious (1 gallon-plus per day) steady coolant leak. Radiator fan still kicks in if coolant temp rises too high. Visual inspection with engine running shows steady drip at the water pump area near the battery box. Can't see the exact source of the leak. How do you know whether it's the water pump or just a failed gasket (or perhaps a leak at the thermostat and its housing)? I plan on changing the pump, gasket, and water pump belt, but should you change the thermostat/housing as well? How do you pick the best aftermarket water pump? Does it matter whether it uses metal or plastic impellers? THANKS from BOSTON
A pressure test of the cooling system should reveal leaks that might not otherwise be obvious. You could also add fluorescent dye to the coolant and use a UV light to look for leaks. If it's losing that much it should not be too difficult to find where it's going. On a 20-year-old vehicle, core plugs leaking are certainly a possibility.
I would prefer a water pump with a metal impeller. I've seen the plastic ones come loose. (The metal impeller can corrode of course but that would not be a problem if coolant is maintained.)
Thanks for the reply, Chuck. As a shade tree, DIY driveway mechanic, changing the pump and the thermostat/housing are reasonably easy. Doing the pressure testing and dye job inspection less so. From seeing coolant on the ground, I'm pretty sure it's a single leak point. I'm inclined to just change the pump and belt and skip a new thermostat and housing unless recommended. How often do the thermostat housings develop leaks? I've read the water pumps on the X-Type/Ford Mondeo are prone to fail, but have never heard much about other weak spots other than hoses. THANKS AGAIN
Take a look at the thermostat housing to see if it's cracked or pitted. If not there's no reason it can't be re-used. (Unless it's plastic which some cars have, if so I'd get a metal replacement.) A pressure test really isn't difficult with a testing kit and I've found loose clamps and pinhole leaks that way I probably would not have found otherwise. I have not worked on one of those cars so I really can only make general recommendations.
Thanks again!