How to Fix a Truck Water Pump

Replacing a water pump on a car or pickup can often be done by a do-it-yourself project in a backyard or on a driveway, and may save a considerable amount of money compared with taking it to a garage. Here are some steps to help you with this project.


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    Assess the project. Cars and trucks vary greatly, depending on the engine and accessories it is equipped with. You should find the water pump, then look at how much equipment must be removed to access it. Here are some things to look at to help you identify your water pump.
    • Many water pumps have the cooling fan mounted on the front. They may also have a fan clutch attached to the fan itself.
    • Most water pumps are mounted on the drive belt end of the engine. For conventional engines, this would be the front most area, for transverse engines, it would be the left side, facing the engine compartment from the from of the vehicle.
    • The water pump will have at least two coolant hoses attached to it, usually between 1- 1/2 inch and 2 inch (5.1 cm) diameter, and may also have the heater core supply hoses (about 3/4 inch) attached as well.
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    You will also need to look for accessories or conditions that will make removing the pump difficult. These include the following.
    • Air conditioning compressor. This device shouldn't be removed by inexperienced individuals, since accidentally discharging it can cause serious problems. Compressors are often mounted above the water pump, and can be difficult to work around.
    • Power steering pump. This item should be located in a position that doesn't cause difficulty accessing the water pump.
    • Alternator. This device is often above the water pump and is usually fairly easy to navigate around while working, but it is also not too difficult to remove if needed.
    • Fan shrouds. This metal or plastic device funnels the air through the radiator to increase the efficiency of the cooling system, and must often be removed to access the water pump. It may be held in place with clips or machine screws, and shouldn't be too difficult to remove.
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    Determine if you will be able to reach all the bolts that must be removed to remove the water pump, using the above information as a guide. If you are fairly sure you can get to all the bolts, both to remove and reinstall them, continue, but if you have doubts, you may want to reconsider this project.
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    Make sure the water pump requires repair. Cooling systems can fail to perform properly for a number of reasons, including leaking hoses, clogged radiator vents, and low coolant levels caused by other factors. The following are common symptoms of potential or present water pump failure.
    • Water dripping from the weep hole in the water pump shaft.
    • Grinding or screeching sounds coming from the water pump indicating a bearing failure.
    • Wobble or loose play in the front shaft of the water pump.
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    Locate a source for a replacement for your water pump. Auto parts stores sell rebuilt or new replacement parts, but some may require special order and may take several days for the part to arrive. Some exotic vehicles may require purchasing or ordering a dealer only replacement part. BMW(s), Jaguars, MG(s), and other cars are examples of this.
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    Make sure you have the tools required for the project. Basic wrenches, included end wrenches, sockets, and ratchets are a must have, and you may find you also need screw drivers, nut drivers, pliers or other tools for removing compression clamps, and a gasket scraper. You may also find a torque wrench is needed to properly tighten the bolts when you reinstall them.
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    Make sure you have the required materials needed to reinstall the water pump, as well. You will need:
    • A water/oil proof gasket sealant suitable for moderate high temperature use. Aviation Form-a-Gasket or RTV Silicon are examples.
    • Gasket material if the pump doesn't come with a replacement gasket set.
    • Antifreeze/coolant suitable for your vehicle.
    • Replacement parts like radiator hoses, clamps, and belts if you want to replace these while you have them off.
    • Hand cleaner, rags for cleaning parts, and other sundry items.
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    Park the vehicle in a place you can leave it while you complete the project. Unexpected delays may mean the care will be in one place for several days, so make sure you are not blocking your driveway or garage doors.
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    Allow the engine to cool off completely before beginning to remove parts.
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    Disconnect the battery cables, removing the negative cable first to avoid shorting.
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    Remove the serpentine belts or vee belts from the front of the engine if necessary.
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    Remove any accessories necessary to access the water pump(see Step 1), tying items you don't want to disconnect like alternators and power steering pumps out of the way.
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    Drain the radiator by placing a catch container underneath the pit-cock or drain plug at its bottom, then opening the drain. Loosening the radiator cap will speed this step up considerably.
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    Remove the fan and fan clutch if they are attached to the water pump, making sure to keep bolts, nuts, and washers separated for re-installation later.
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    Remove the radiator hoses from the water pump. Some hoses are attached with spring type compression clamps, others are held on with high-gear screw type clamps. Use a screwdriver to pry off stubborn hoses.
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    Remove the bolts that attach the water pump to the engine, making sure, once more, to keep these from getting mixed up with other bolts and fasteners. Notice if the threads of these bolts have a blue or red plastic-like material on the threads, and if so, make a note of their position since they may require thread sealant when they are reinstalled. Also note, often there are different length bolts on water pumps, and using a bolt that is too long for the hole may result in damaging your engine.
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    Pull the water pump off the engine. If the water pump refuses to budge, recheck to make sure all bolts have been removed, then use a screwdriver or pry bar to break it loose. Often, a water pump installed with sealant can be stuck fast and require substantial force to break it loose.
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    Compare the old water pump to the new one you have purchased to make sure it is exactly the same, including bolt positions, and shaft length.
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    Remove all remaining gasket adhesive and material from the mounting surface of your old water pump. Leaving even a small amount of debris will cause the new assembly to leak, requiring a complete disassemble to correct this problem.
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    Apply a thin, uniform coat of gasket sealer to the mounting surface where the new gasket will fit, making sure no excess sealant is inside the water pump chamber itself. Also, apply a similar coat to the water pump base.
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    Place the water pump gasket on the sealant on the water pump, pressing it firmly in place while making sure it is aligned correctly.
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    Position the water pump in place, being very careful the gasket stays in the proper position. Install a couple of bolts (again, making sure any bolts that require thread sealant are coated before proceeding) to hold the water pump in place. When all the bolts are started in the water pump, tighten them in a criss-cross pattern so the gasket seats properly. Note that many service manuals call for specific torque requirements for the installation of your water pump, so if you are in doubt of your ability to properly tighten the bolts, invest in a good torque wrench for this step.
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    Reinstall the water hoses on your water pump, making sure all the clamps are tightened snugly. You may want to replace these items, as noted earlier, if they appear to be deteriorated or damaged.
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    Reinstall the rest of the components you removed during the tear down process. Make sure all belts are tensioned properly and the drain plug is reinstalled or tightened as required.
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    Fill the radiator with coolant (if you suspect you may have a leak, use clear water to test the system prior to use of expensive coolant).
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    Replace the battery cables after all the other components are reinstalled and secured, then crank the engine and check for leaks. You will want to top off the coolant after you have determined you don't have any leaks and the engine has heated up to normal operating temperature, since the engine block cooling channels will have to fill when the thermostat opens.


  • Purchase a service or repair manual if you don't feel comfortable with your project.
  • Carefully note the location of each bolt, nut, and washer, as these parts are usually not interchangeable with others.


  • Never open the cooling system of a vehicle when it is hot.

Things You'll Need

  • Nut driver
  • Replacement water pump
  • Drain pan
  • Wrench set

Article Info

Categories: Trucks