The water pump is definitely the heart of the cooling system. The pump circulates coolant amongst the engine and radiator to maintain the engine from overheating. In the pump is actually a metal or plastic impeller with blades that push the water with the pump. The impeller is mounted on a shaft that’s supported from the pump housing that has a bearing and seal assembly. The water pump is usually belt driven and it is mounted on the front of the engine.


Water pumps ordinarily fail one of two approaches: the shaft seal starts to leak, or the impeller inside breaks, comes loose or the blades erode and wear down (that is more of the challenge with pumps which have plastic impellers).

Any time a water pump begins to leak, the cooling system will eliminate coolant. In case the leak will not be discovered, the reduction of coolant will gradually result in the engine to overheat. The drive may possibly not recognize anything is incorrect till the temperature warning light comes on. If this happens for you, shut the engine off straight away. Significant engine damage can result if an overheating engine is driven also far.

If your engine has overheated, the entire cooling system (radiator, hoses, water pump and engine) ought to all be inspected to determine if there are actually any coolant leaks. If coolant is leaking from the water pump shaft or vent hole, the water pump has to be replaced. Cooling system sealer are not able to quit this type of leak.


A seal on the water pump shaft prevents coolant from leaking previous the bearing. Seal wear may be brought on by rust, sediment or other contaminants which might be circulating with the coolant inside the cooling system. The pump shaft and bearings will also be beneath continuous load not simply in the drive belt or timing belt but in addition the fan on motor vehicles with pump-mounted mechanical cooling supporters. Finally the water pump shaft seal and/or bearing wears out and the pump begins to leak.

Most OEM water pumps are intended to go 100,000 miles or more, but they never always go the distance. It is not uncommon to see leaks occur just after 50,000 or 60,000 miles. In case the pump shaft displays any noticeable wobble or the bearings are producing noise, the pump need to be replaced even though it isn’t leaking (because it quickly will be!).


Often a water pump will fail internally on account of extreme corrosion sporting away the impeller blades, or the impeller comes loose on the shaft, or even the shaft itself may perhaps break from metal fatigue (attributable to flexing due to an out-of-balance fan).

Quite a few late model cars (Chrysler particularly) have plastic impellers to enhance cooling performance and also to cut down cavitation (drag). But the plastic can wear down swiftly in case the coolant is dirty and contains abrasives. The pump could not leak, nonetheless it may perhaps not circulate sufficient coolant throughout the engine to maintain the engine at normal operating temperature.

squeeze radiator hose to check coolant flow

One strategy to check to get a negative water pump should be to squeeze the upper radiator hose once the engine is hot and idling. Mindful, because the hose shall be HOT! For those who don’t feel significantly coolant circulating with the hose after you rev the engine, the pump may very well be undesirable. The other induce might be a terrible thermostat that is not opening adequately (remove and inspect the thermostat), or even a clogged radiator.

The best way to Replace A WATER PUMP

Replacement water pumps can be found in a broad selection of sizes and shapes together with shaft lengths, and on some engines in excess of one type of pump could possibly be made use of. Locating the right pump usually means matching not only the yr, make, model and engine, but from time to time also the VIN or casting quantity. If achievable, compare the replacement pump for the outdated pump to produce confident it is the suitable one for the application. To consolidate applications, some replacement castings have further outlets and mounting bosses or bolt holes so it may possibly be employed on a wider variety of engine applications. This is certainly okay provided that you will find sufficient outlets and mounting bosses to match the original casting.

To Change Your Old Water Pump:

1. Drain the radiator. Open the petcock valve in the bottom in the radiator, or if there’s no drain valve, loosen the reduced radiator hose. Do this if the engine is COLD. Catch the coolant inside a bucket for reuse later, or protected disposal if it is actually time to change the coolant. Use antifreeze can commonly be flushed down the toilet. Don’t dump it into a storm sewer or on the ground for the reason that it can be toxic and can destroy plants. Additionally it is poisonous to animals and people.

2. Remove the fan belt. On engines with a serpentine belt drive, what this means is loosening the tension on the automatic tensioner. Note how the belt is routed Right before you remove it so you can reinstall it later effectively (draw a image if there exists not a belt decal under the hood that shows how the belt is routed around the pulleys).

3. Remove something else that’s the way in which. This might include the fan, fan shroud, timing belt cover in case the pump is driven off the timing belt on an OHC engine rather of the serpentine belt, or any brackets or other engine-mounted accessories which have been blocking access for the pump.

4. Unbolt the water pump from the engine.

5. Clean the pump mounting surface to remove all traces of outdated gaskets. The mounting surface need to be clean and dry befoe you set up the brand new pump.

6. Position the gasket to the new pump, utilizing gasket sealer or adhesive as demanded, then bolt the new water pump towards the engine. Use thread sealer on any threads that screw each of the way via into open water jackets (not wanted with blind bolt holes).

7.Refill the cooling system. Be patient since it could consider some time for many of the air to vent out. Many cooling programs have vent valves which can be opened for the duration of a refill to allow air a area to escape.


If your cooling system consists of rust or sediment, the radiator and block must be cleaned and flushed Ahead of you remove the outdated pump to guard the new pump from possible harm.

If your coolant which you drained out of the radiator is rusty or dirty, never reuse it. Refill the cooling system using a 50/50 mixture of new antifreeze and clean, distilled water. Do not use tap water or softened water since it consists of minerals and salts that can bring about corrosion inside the cooling system.

If your motor vehicle includes a pump-mounted mechanical fan with a fan clutch, the fan clutch need to also be replaced at the similar time. The services existence with the fan clutch is concerning the identical since the pump. A slipping fan clutch will lower radiator cooling and may perhaps trigger the engine to overheat.

Other parts that could be needed to finish the job contain a fresh thermostat (advisable if the engine overheated), new radiator and heater hoses (hoses that happen to be cracked, brittle or unusually soft need to be replaced), and new hose clamps.