If the water pump on a 2004 Chevy TrailBlazer goes bad, it can spell disaster for the engine. Overheating can cause the engine to seize up and require huge amounts of maintenance before the vehicle is operational again. The water pump is below the fan shroud in a hard to reach area, so replacing the part will take considerable time and effort--set aside between 2 and 3 hours for the project unless you are an experienced mechanic. When purchasing a new water pump, don't forget to get new gaskets; they must also be replaced.
Park the TrailBlazer on a flat surface and set the parking brake. Open the hood and disconnect the battery.
Place the drain pan underneath the radiator drain plug, on the passenger side of the radiator. Remove the drain plug with a socket wrench, and allow it to drain completely. Replace the drain plug and tighten it down.
Loosen the hose clamps on the upper radiator hose with a screwdriver. Remove the upper radiator hose.
Remove the two radiator fan shroud bolts with a socket wrench. Disconnect the fan clutch clip. Squeeze the sides of the fan clutch clip and wiggle it back and forth while pulling on it to disconnect it.
Loosen the fan clutch bolt with a crescent wrench. This bolt can be very difficult to break loose--use a hammer or a torsion bar if necessary. Remove the nut. Push in on the fan and pull upward on the fan and shroud at the same time to remove them as a single unit.
Loosen the bolt in the center of the tension pulley with a socket wrench. Adjust the placement of the pulley so the serpentine belt can be removed. Remove the serpentine belt.
Move the drain pan under the water pump. Remove the five bolts that hold the water pump to the engine. Remove the water pump and old gasket. Scrape off any stuck gasket pieces with a screwdriver.
Install the new water pump and gasket. Replace all the parts in reverse order, exactly as they were removed.
Fill the radiator with coolant. Start the Trailblazer and let it idle so that coolant can run through the hoses. Top off the radiator.
