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Having just read a couple of these inaccurate articles, I felt compelled to write myself.I read one which seemed to think that a failing water pump would stop the circulation of the water.No necessarily so! The water pump is merely an impeller, or internal propeller meant for moving water rather than moving an object in the water.If the Timing belt, fan belt or other transmission device is still functional, then the impeller will rotate, and the water will circulate.OK so symptoms of a water pump failure.Firstly, you may notice steam. Another mistake was that the writer stated the water boils at 212 degrees Fahrenheit or 100 degrees Celsius, but not always. That measure is at sea level with 14psi atmospheric pressure. In an enclosed and sealed system, the pressure is allowed to increase, thus raising the temperature of boiling.This means that when the water hits the atmosphere, it will steam.You should find wetness or discoloration under the bonnet (hood). You could at this point, add a radiator self-sealing compound, which will circulate to the leak and harden, fixing it. However, because the shaft of a water pump is in motion, any compound will be broken away and the leak will continue. These products are not to be recommended anyway, as they can block the small galleries in the cars heater matrix and return pipes.On the output shaft of the water pump, there is a bearing, that is sealed for life with rubber/plastic seals on each side of the ball bearing cage, and on some models a backup seal as well. If this seal fails, water will be allowed into the bearing, causing rapid wash-out of the grease. Without lubrication, it won't be long until the case hardened ball bearings damage the bearing track on which they are running. The track becomes pitted and uneven, causing a 'rumble'.This can increase to a whine, and then a hideous screech.Early diagnosis with a mechanics stethoscope probe can pick up the rumble.

Also, you can get a cooling system hand pump, and pressurize the system through the header tank cap. This will force out the water while cold, which is much easier to find, than peering through a steam screen.Early diagnosis is essential when the pump is timing belt driven. If the pump seizes, it can strip the teeth on the timing belt, causing miss-timing and the bending of the valves, and even smashing pistons, or connecting rods when a valve head breaks off. Mucho money. So, to summarize. Leak, and steam.pressure test, stethoscope test.Always fit a new timing belt if you have to relax the tension on it.When replacing the pump, always use fresh anti-freeze, as the additives in it will stop corrosion extend the boiling point of coolant, and of course, stop freezing. Freezing can also wreck your engine by stopping the impeller shaft from moving in ice, stripping timing belt teeth and killing your engine. Never skimp on anti freeze!Happy cooling to you all!

Learn more about this author, Andy Cutler.
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