Draining and Filling Cooling System
DRAINING COOLING SYSTEMWARNING: DO NOT REMOVE THE CYLINDER BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR DRAINCOCK WITH SYSTEM HOT AND UNDER PRESSURE. SERIOUS BURNS FROM COOLANT CAN OCCUR.
DO NOT WASTE reusable coolant. If the solution is clean, drain the coolant into a clean container for reuse.
DRAINING ENTIRE SYSTEM
Use this procedure if the entire cooling system is to be drained, such as for engine removal.
1. DO NOT remove radiator cap first. With engine cold, raise vehicle on a hoist and locate radiator draincock.
- 4.0L 6-cyl. Engine: Radiator draincock is located on the right/lower side of radiator facing to rear of vehicle.
- 4.7L V-8 Engines: Radiator draincock is located on the left/lower side of radiator facing to rear of vehicle.
2. Attach one end of a hose to the draincock. Put the other end into a clean container. Open draincock and drain coolant from radiator. This will empty the coolant reserve/overflow tank. The coolant does not have to be removed from the tank unless the system is being refilled with a fresh mixture. When tank is empty, remove radiator cap and continue draining cooling system.
To drain the 4.0L 6-cylinder engine of coolant, remove the cylinder block drain plug located on the side of cylinder block.
To drain the 4.7L V-8 engines of coolant, remove the cylinder block drain plugs located on the sides of cylinder block above the oil pan rail.
PARTIAL DRAINING
Use this procedure if the coolant is to be partially drained, such as for engine thermostat removal.
1. With engine cold, slowly remove the radiator cap. Raise vehicle on a hoist and locate radiator draincock.
- 4.0L Engine: Radiator draincock is located on the right/lower side of radiator facing to rear of vehicle.
- 4.7L Engines: Radiator draincock is located on the left/lower side of radiator facing to rear of vehicle.
2. Attach one end of a hose to the draincock. Put the other end into a clean container.
3. Open draincock and drain desired amount of coolant from radiator.
REFILLING COOLING SYSTEM-4.0L ENGINE
1. Tighten the radiator draincock and the cylinder block drain plug(s) (if removed).
2. Fill system using a 50/50 mixture of ethylene glycol antifreeze and low mineral content water. Fill radiator to top and install radiator cap. Add sufficient coolant to the reserve/overflow tank to raise level to FULL mark.
3. With heater control unit in the HEAT position, operate engine with radiator cap in place.
4. After engine has reached normal operating temperature, shut engine off and allow it to cool. When engine is cooling down, coolant will be drawn into the radiator from the reserve/overflow tank.
5. Add coolant to reserve/overflow tank as necessary. Only add coolant to the reserve/overflow tank when the engine is cold. Coolant level in a warm engine will be higher due to thermal expansion. To purge the cooling system of all air, this heat up/cool down cycle (adding coolant to cold engine) must be performed three times. Add necessary coolant to raise tank level to the FULL mark after each cool down period.
REFILLING COOLING SYSTEM-4.7L ENGINE
1. Tighten the radiator draincock and the cylinder block drain plug(s) (if removed).
CAUTION: Failure to purge air from the cooling system can result in an overheating condition and severe engine damage.
2. Remove the cooling system bleed plug from the radiator upper hose inlet housing. Fill system using a 50/50 mixture of ethylene-glycol antifreeze and low mineral content water, until coolant begins coming out of the cooling system bleed hole. Install the cooling system bleed plug. Fill radiator to top and install radiator cap. Add sufficient coolant to the reserve/overflow tank to raise level to FULL mark.
3. With heater control unit in the HEAT position, operate engine with radiator cap in place.
4. After engine has reached normal operating temperature, shut engine off and allow it to cool. When engine is cooling down, coolant will be drawn into the radiator from the reserve/overflow tank.
5. Add coolant to reserve/overflow tank as necessary. Only add coolant to the reserve/overflow tank when the engine is cold. Coolant level in a warm engine will be higher due to thermal expansion.