How to Fix a Car's Water Pump

Typical automotive water pumps

Automotive gasoline engines use a coolant-water mixture cycled through a radiator by a water pump to lower the operating temperature of the motor. The water pump can become corroded or wear out, and will require replacement when they fail. The water pump's bearings are designed to leak when they fail, and they cannot be repaired easily. The average backyard mechanic can replace a water pump in most cars in about an hour.

Things You'll Need

• Socket set
• Screwdrivers
• Wrenches
• Drain pan
• Coolant

Instructions

Replacment of an automotive water pump

1. 

   Drain the coolant from the system by loosening the drain plug on the radiator or uncoupling the lower coolant hose. Uncap the radiator to release the negative pressure and allow the coolant to drain until the system is empty.

2. Remove the fan belts or serpentine belt that drives the water pump by firmly pressing on the tension pulley and then pulling the belt off, or loosening the accessory that gives tension to the pump's belt.

3. Unbolt the water pump's pulley by turning the heads in a counterclockwise direction. Normally, the pump itself is held with two to four bolts to the engine, but the pulley is too large to access the pump's bolts. In these cases, disassembling the pulley will allow access to them; the water pump pulley is a halved design, and will come apart once disconnected.

4. Unbolt and remove the old water pump by turning the bolts in a counterclockwise direction. The pump will pull straight out, and may spill trapped coolant when it comes free. There is a gasket on the inside rim of the pump, and there should be a new one included with the new pump. Clean the area around the water channel (where the pump was mounted) and scape off any old gasket material.

5. Apply the new gasket and any adhesive included to the new water pump. If the pump's lip has a certain shape, then the gasket will only fit one way. Many pumps simply have a circular opening. Having this gasket seated properly is crucial to the life of the new pump.

6. Install the new pump by bolting it to the engine and attaching the old pulley. Replace the belt, and apply tension by either releasing the tension pulley or tightening the accessory that applies pressure to the pump.

7. Tighten the drain plug on the radiator and reattach any disconnected hoses.

8. Refill the system with coolant by filling the radiator, then cranking the car and continuing to pour in coolant until it does not take in any more. Cap the radiator, then fill the reservoir tank to the proper level.

Tips & Warnings

• Use a 60 percent coolant and 40 percent water mix for the first few months after changing the water pump. The raw metal needs the extra protection of the chemicals in the coolant.

• Dispose of coolant by taking it to an auto parts store for recycling.

References

• Water Pump Replacement