How to Replace the Water Pump for a 2003 Corolla

The water pump in your Toyota Corolla is responsible for delivering its engine coolant. A malfunctioning one will lead to an overheating engine and needs to be replaced. The pump on the 2003 model is mounted directly on the timing chain cover. You will need to work around a number of other components in the engine due to the compact car's smaller engine space. Due to the extremely hot temperature the engine coolant can reach, you should only perform this when the engine is cool.

Instructions

Disconnect the Corolla's negative battery cable.

Connect a 3/8-inch diameter hose to the radiator's drain fitting, remove the radiator cap and open the drain fitting, draining the engine coolant into a large container. The drain fitting may require pliers.

Rotate the drive belt tensioner -- the middle engine pulley on the left -- clockwise with a ratchet and socket to loosen the drive belt and remove it from the pulleys.

Disconnect the alternator's electrical connectors and then unbolt and remove the alternator with your wrench.

Remove the six mounting bolts for the alternator and remove it from the engine. Take note of where each bolt was installed; the bolts are of different sizes and their positions are important.

Clean off the sealing surface on the engine using acetone or lacquer thinner and remove the O-ring from the sealing groove within the timing chain cover.

Insert a new O-ring into the water pump's sealing groove on the timing chain cover.

Install the replacement water pump into the engine and apply each bolt in the same location it was before. Tighten the small bolts to 80 inch-pounds with a torque wrench and the large ones to 96.

Reconnect the alternator with its bolts and electrical connectors.

Slip the drive belt back onto the pulleys (the radiator shroud should have a diagram to help you with the routing path), loosen the tensioner, slip the belt over the tensioner and slowly release the tensioner.

Refill the engine coolant -- use a fresh mixture of engine coolant and water if the old substance is contaminated -- and reconnect the battery cable.