Tools You'll Need:
* Repair Manual: Essential for torque specs and detailed instructions.
* Socket Set: Various sizes, including metric and possibly SAE.
* Wrench Set: Open-end and combination wrenches.
* Ratchet and Extensions: To reach difficult bolts.
* Screwdrivers: Phillips and flathead.
* Pliers: Needle-nose and slip-joint.
* Drain Pan: To catch coolant.
* New Water Pump: Make sure it's the correct one for your engine.
* New Gasket(s): For the water pump and possibly others.
* New Thermostat (optional but recommended): While you're in there, replacing the thermostat is a good preventative measure.
* Coolant: The correct type for your Jeep (check your owner's manual).
* Jack and Jack Stands: For safe working conditions.
* Gloves and Safety Glasses: Essential for protection.
General Steps (4.0L Engine Example):
1. Safety First: Disconnect the negative battery terminal. Let the engine cool completely before starting. Raise the front of the Jeep and secure it on jack stands.
2. Drain the Coolant: Locate the drain plug at the bottom of the radiator and carefully drain the coolant into your drain pan.
3. Remove Accessory Belts: Loosen the belt tensioner and remove the serpentine belt(s). This usually involves a special tool or careful manipulation of the tensioner pulley.
4. Remove Fan and Fan Shroud (if applicable): This may require removing the fan clutch and possibly some bolts securing the shroud.
5. Remove Water Pump Pulley: Use the appropriate socket to remove the bolts securing the water pump pulley.
6. Remove Water Pump: This is where it gets tricky. The water pump is usually bolted to the engine block. You'll need to remove the bolts holding it in place. There might be some stubborn bolts, so use penetrating oil if necessary. Take pictures as you go to aid in reassembly.
7. Clean the Surface: Carefully clean the mating surfaces of the engine block and the water pump to ensure a good seal with the new gasket.
8. Install New Water Pump and Gasket: Apply a thin layer of gasket sealant (if recommended by the manufacturer) to the new gasket and carefully install the new water pump, aligning the bolts. Tighten the bolts to the manufacturer's specified torque.
9. Reinstall Pulley, Fan, and Shroud: Reinstall the water pump pulley, fan, and fan shroud in the reverse order of removal.
10. Reinstall Belts: Reinstall the serpentine belt(s), ensuring proper alignment.
11. Refill Coolant System: Carefully refill the coolant system with the correct type and amount of coolant. Check for leaks.
12. Bleed the Air from the System: Run the engine for a few minutes, then let it cool. Top off the coolant as needed and check for leaks. There are various ways to bleed air from a cooling system – consult your repair manual.
13. Lower Vehicle: Carefully lower the vehicle from the jack stands.
14. Final Check: Run the engine for a while, monitoring temperature gauges and checking for any leaks.
Important Considerations:
* Timing Belt: If your Jeep has a timing belt, you may need to remove it to access the water pump. This is a much more complex procedure requiring special tools and knowledge. If you are not comfortable doing this, take it to a professional mechanic.
* Professional Help: If you are not comfortable performing this repair yourself, take your Jeep to a qualified mechanic. Improper repair can lead to serious engine damage.
This is a simplified overview. Always refer to a repair manual specific to your 1990 Jeep Cherokee and its engine for detailed, step-by-step instructions and torque specifications. Failure to follow the correct procedures can result in damage to your engine or personal injury.
