Some automotive issues make themselves known instantly and in a big way. But signs of a bad water pump aren’t always so brash. A bad water pump can wreak havoc on your engine and should not be taken lightly. But how does a water pump go bad? Here’s a few bad water pump symptoms that can help you deduce if repairs are in order.
One of the most common symptoms of a bad water pump is a leak from the water pump itself. Many water pumps are constructed with a weep hole below the pump drive shaft. Normally this weep hole is dry as the pump drive shaft seals keep the coolant at bay and away from the water pump bearings. But if the seal fails coolant can then seep past harming the water pump bearings and dripping out of the weep hole. The driver may notice a sweet smell of coolant cooking off the hot engine or a small puddle of coolant under the vehicle when parked. If the coolant is dripping on the accessory drive belt system there may be damp areas under the hood. If your vehicle develops a coolant leak or you find yourself adding coolant to keep it filled, check the area around the water pump just in case.
One of the common signs of bad water pump functionality is overheating. The pump may not leak coolant, but the pump mechanism itself may have failed. Over time the fins of the pump can actually wear down to the point where they are no longer moving coolant. Cavitation can eat away at the metal pump vanes and pump surfaces. Plastic water pump vanes can disintegrate over time as the plastic ages. This all adds up to coolant that is no longer moved through the engine block and into the radiator to be cooled, leading to overheating.
Water pumps have bearings that have to stand up to not only engine heat but also tension from the drive pulley. If you start to hear a grinding noise or high pitch squealing from the front of the engine, the water pump may be trying to tell you something. Try and rule out squealing belts by double checking belt condition and belt tension. Once you are sure the belt isn’t the cause try to pinpoint the source of the bad water pump noise. Be careful to not place any body parts near that rotating accessory drive system or the engine cooling fan. Simply stand in front of the running engine with the hood open and observe for a few minutes.
How to tell if water pump is bad can sometimes depend on the design of the engine. Some water pumps are buried inside the engine which makes it difficult to observe any problems. For example Ford Duratec V6 engines have the water pump located behind the timing cover. A leak from the water pump will allow coolant to mix with oil around the timing chains but the leak will not be visible on the outside of the engine. Checking the engine oil regularly and looking for an increase in oil level (due to coolant collecting in the oil pan) or a milkshake-like oil appearance are signs of possible symptoms of a bad water pump. Unfortunately these can also be signs of a bad cylinder head gasket, so further investigation will be required.
Any of these symptoms should be taken seriously and further investigation as to the source of the problem. If a bad water pump is diagnosed, it should be replaced immediately. Don’t risk ruining an engine by putting off a repair that is relatively minor.
Check out all the heating & cooling systems parts available on NAPAOnline or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on how to know tell if your water pump is bad, chat with a knowledgeable expert at your local NAPA Auto Parts store.
With an automotive writing career spanning over two decades, Brian has a passion for sharing the automotive lifestyle. An avid DIYer he can usually be found working on one of his many project cars. His current collection includes a 1969 Olds Delta 88 convertible, BMW E46 sedan, and a slant-6 powered 1975 Plymouth Duster.