There are some parts of a vehicle that, when failing, do not need to be immediately replaced. A water pump is not one of those parts. Due to the vital role the pump plays in cooling the engine, if it stops working, there will be fast consequences including possible all-out engine failure. Replacing a bad water pump isn’t a quick job, but it’ll save you from the worse job of replacing your engine. Know the signs of when you have a bad water pump on your hands.
The water pump moves coolant through the radiator and around the engine to dissipate heat buildup. Rapidly moving, closely connected metal parts generate a lot of friction, and thus, heat. Too much heat and you end up with components that are warped, melted, fused, broken and otherwise structurally compromised. The water pump is usually pulley driven by the accessory drive belt, serpentine belt, or timing belt. A worn out belt can prevent your water pump from operating at peak efficiency. Internally, there is an impeller that keeps the system circulating. Over time the impeller can actually wear down due to contaminants in the coolant. Cavitation can also cause the impeller to erode and lose the ability to pump coolant.
One telltale sign of a soon-to-be-faulty water pump is a noticeable coolant leak toward the front of the vehicle. If the car is left overnight and you notice an orange or green (depending on the coolant you use) puddle on the ground, suspect the pump. But don’t assume that a lack of coolant on the ground doesn’t mean you don’t have a water pump leak. If the coolant reservoir is low but there is no visible coolant leak, check your oil dipstick. If it looks frothy or like a chocolate milkshake, you may have an internal water pump leak. Certain Ford Duratec V6 engines can leak coolant internally behind the timing chain cover.
A slow leak over time will cause a bunch of gunk to build up around the pump. Look for coolant trails leading down from the pump, or a kind of gelled coolant deposit around the outside. Some water pumps have a “weep hole” beneath the pump shaft that will leak coolant once the internal seals have worn out, a sure sign of a bad water pump. You might also see a good deal of rust around the pump and, if you look closely, pitting (corrosion that creates small holes in the metal) or cavitation (formation of cavities in a liquid) on the mounting surface. All of this indicates a slow leak. While this doesn’t result in immediate failure, it will create a low-coolant condition (which is quite bad) and allow the lubrication protecting the moving parts inside the pump to escape (which will ruin the bearing).
A loose accessory belt will cause a whining noise that increases with acceleration. The fix for this could be as simple as tightening the belt, replacing the belt, or replacing the belt tensioner. If you hear a grinding or growling noise from the front of the engine, however, that indicates a bad bearing. There are other bearings on the front of the engine that can fail, but in any case you should immediately take it to a mechanic to confirm and repair the problem.
Once the pump has failed, your engine will overheat. If you haven’t noticed other signs of impending failure, take note of this one. If the “Low Coolant” light comes on, add coolant ASAP and check for a major leak. If the temperature gauge rises above normal or a temperature warning light comes on, pull over and call a tow truck. Once the water pumps fails there is no safe amount of time you can run the engine without possibly causing serious damage. While turning on the heater may help cool down an engine with radiator issues, without a pump to circulate the coolant this trick won’t help in this case. The smart move is to park it.
If you see smoke or steam coming from your radiator or under the hood generally, your engine is too hot and has probably already suffered a lot of damage. Pull over immediately and call for help. Wait for the engine to cool off before poking around, as you’re dealing with scalding-hot coolant and potentially other unexpected dangers. Not only is your cooling system superheated, but it is also under pressure. It is best to wait a few hours for everything to cool down before beginning a diagnosis.
Because it’s located in the front of the engine behind the fan or crammed next to a strut tower, accessing a bad water pump can sometimes involve a significant amount of tear down. It’s definitely a pain of a component to have replaced, but it’s worth it. Do yourself a favor and pay attention to the warning signs before it’s too late for your engine.
Check out all the heating & cooling systems parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on whether you have a bad water pump, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
Photos courtesy of Blair Lampe.
Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter. In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.