What Are the Symptoms of a Leaking Water Pump?

Ignore a leaking water pump in vehicle equipped with an aluminum head engine and you may end up with warped heads caused by the overheating of the engine. The expense to replace warped heads is far greater and takes a lot longer to complete than simply replacing a leaking water pump. Identifying the difference between the normal coolant overflow and a leaking water pump requires careful investigation of the vehicle's engine compartment and paying attention to what the vehicle tells you.

Noises

All vehicles talk to you -- they tell you when things are fine by humming along in a rhythmic pattern; on the other hand, they squeal at you when something's wrong. Water pump bearings on the verge of failure tell you about it in a series of high-pitched squeals, clicking or other such noises. If you've been remiss in ensuring your vehicle's cooling system has enough coolant in it by only putting water into the cooling system, the water pump's impellers could be rusting internally as well (unless they're plastic). Because the water pump turns with the engine's revolutions to pump coolant through the engine, faulty bearings and failing water pumps often make strange noises, out of sync with the engine's normal sounds. When you replace the water pump and notice excessive rust in the coolant system, flush the radiator and engine block until all rust is gone before filling up with new coolant.

Coolant on the Block

One sign of a leaking water pump is water or coolant found on the exterior of the engine block. This is a hard one to spot because the heat of the engine dries water or coolant leaks here quickly. The water pump mounts in a variety of locations on an engine block, and is found powered by the vehicle's serpentine belt, depending upon the configuration of the vehicle. Find a repair manual to identify the appearance of the water pump for your specific vehicle, and check it for leaks. Rock it back and forth and test the pulley for play. If the gasket is bad, water will leak out when you try to move it.

Engine Overheats

When you notice an increase in the coolant's system temperature or odd fluctuations on the engine temperature dial on the engine's dashboard, this is indicative of a fault in the cooling system. If the engine consistently overheats, the first culprit to look at is the water pump. When you replace the pump, it's a good practice to replace the thermostat at the same time. Engines that overheat destroy the effectiveness of the thermostat, often ruining it to the point where it won't work at all. The thermostat, when it reaches the appropriate temperature (approximately 212 degrees Fahrenheit), opens to allow the coolant into the engine block. When it fails, your vehicle will quickly overheat, even if you had replaced the water pump (but forgot to replace the thermostat).

Low Radiator and Overflow

A leaking water pump leads to a low radiator and coolant overflow container. If you find yourself filling up the coolant overflow more than usual, it's time to look at the water pump. Water pumps require replacement at or around 100,000 miles, again depending upon the vehicle. After removing the water pump, clean the block face of any leftover or old gasket material. You need a clean area to ensure the gasket seals after installing the new water pump.

Water Under the Engine

If you note water, orange or green coolant underneath the engine, away from where the coolant overflow sits, this is a good sign the water pump leaks. Because the water doesn't circulate until the pump turns over with the belt's rotation, check for leakage when the car is in park, but the engine is on. Look underneath the engine, below where the water pump sits on the block, and check for leakage. If you find leaks, replace the pump -- and replace the thermostat at the same time.