Engine Cooling System - Diagnosis Dodge Grand Caravan IV

DESCRIPTION - COOLING SYSTEM

The cooling system components consist of a radiator, electric fan motors, shroud, pressure cap, thermostat, transmission oil cooler, water pump, hoses, clamps, coolant, and a coolant reserve system to complete the circuit.

DESCRIPTION - HOSE CLAMPS

The cooling system uses spring type hose clamps. If a spring type clamp replacement is necessary, replace with the original Mopar® equipment spring type clamp.

Scheme 1

OPERATION - COOLING SYSTEM

The engine cooling systems primary purpose is to maintain engine temperature in a range that will provide satisfactory engine performance and emission levels under all expected driving conditions. It also provides hot water (coolant) for heater performance and cooling for automatic transmission oil. It does this by transferring heat from engine metal to coolant, moving this heated coolant to the radiator, and then transferring this heat to the ambient air.

1. When engine is cold: thermostat is closed, cooling system has no flow through the radiator. The coolant bypass flows through the engine only.
2. When engine is warm: thermostat is open, cooling system has bypass flow and coolant flow through radiator.

Coolant flow circuits for the 2.4L and 3.3/3.8L engines are shown in (Scheme 2)

Scheme 2

OPERATION - HOSE CLAMPS

The spring type hose clamp applies constant tension on a hose connection. To remove a spring type hose clamp, use Special Tool 6094 or equivalent, constant tension clamp pliers (Scheme 3) to compress the hose clamp.

Scheme 3

DIAGNOSIS AND TESTING - COOLING SYSTEM LEAK TEST

With engine not running, remove radiator pressure cap and wipe the radiator filler neck sealing seat clean. The radiator should be full.

Attach the Cooling System Tester 7700 or equivalent to the radiator, as shown in (Scheme 4) and apply 104 kPa (15 psi) pressure. If the pressure drops more than 13.8 kPa (2 psi) in 2 minutes, inspect all points for external leaks.

Scheme 4

All radiator and heater hoses should be shaken while at 104 kPa (15 psi), since some leaks occur only while driving due to engine movement.

If there are no external leaks, after the gauge dial shows a drop in pressure, detach the tester. Start engine and run until the thermostat opens, allowing the coolant to expand. Reattach the cooling system tester. If the needle on the dial fluctuates it indicates a combustion leak, usually a head gasket leak.

If the needle on the dial does not fluctuate, raise the engine rpm a few times. If an abnormal amount of coolant or steam emits from the tailpipe, it may indicate a coolant leak caused by a faulty head gasket, cracked engine block, or cracked cylinder head.

There may be internal leaks that can be determined by removing the oil dipstick. If water globules appear intermixed with the oil it will indicate an internal leak in the engine. If there is an internal leak, the engine must be disassembled for repair.

DIAGNOSIS AND TESTING - COOLING SYSTEM FLOW CHECK

To determine whether coolant is flowing through the cooling system, use one of the following procedures

PREFERRED METHOD

1. Remove pressure cap when engine is cold. Remove small amount of coolant. Idle engine until thermostat opens. You should observe coolant flow while looking down the filler neck. Once flow is detected install the pressure cap. Replace removed coolant into coolant recovery container.

ALTERNATIVE METHOD

1. If engine is cold, idle engine until normal operating temperature is reached. Feel the upper radiator hose. If it is hot, coolant is circulating.

DIAGNOSIS AND TESTING - COOLING SYSTEM AERATION

Low coolant level in a cross flow radiator will equalize in both tanks with engine off. With engine at running and at operating temperature, the high pressure inlet tank runs full and the low pressure outlet tank drops, resulting in cooling system aeration. Aeration will draw air into the water pump resulting in the following

1. High reading shown on the temperature gauge.
2. Loss of coolant flow through the heater core.
3. Corrosion in the cooling system.
4. Water pump seal may run dry, increasing the risk of premature seal failure.
5. Combustion gas leaks into the coolant can also cause the above problems.

DIAGNOSIS AND TESTING - COOLING SYSTEM DEAERATION

Air can only be removed from the system by gathering under the pressure cap. On the next heat up it will be pushed past the pressure cap into the coolant recovery bottle by thermal expansion of the coolant. It then escapes to the atmosphere in the coolant recovery bottle and is replaced with coolant on cool down.

To effectively deaerate the system, multiple thermal cycles of the system may be required.

Note. Deaeration does not occur at engine idle - higher engine speeds are required. Normal driving will deaerate cooling system.

STANDARD PROCEDURE - COOLING SYSTEM DRAINING

Scheme 5

Scheme 6

1. Without removing radiator pressure cap and with system not under pressure, open the draincock. The draincock is located on the lower left side of radiator (Scheme 5)
2. After the coolant recovery/reserve container is empty, then remove coolant pressure cap (Scheme 6)
3. Remove the cylinder block drain plug(s).

STANDARD PROCEDURE - COOLING SYSTEM FILLING

Remove radiator pressure cap (Scheme 6) and fill system, using a 50/50 mix of Mopar® Antifreeze/Coolant, 5 Year/100,000 Mile Formula and distilled water.

Continue filling system until full. Be careful not to spill coolant on drive belts or the generator. For cooling system capacity, (Refer to CAPACITIES - SPECIFICATIONS ).

Fill coolant recovery/reserve container (Scheme 6) to at least the MAX mark with 50/50 solution. It may be necessary to add coolant to the recovery/reserve container after three or four warm up/cool down cycles to maintain coolant level between the MAX and MIN mark. This will allow trapped air to be removed from the system.

STANDARD PROCEDURE - ADDING ADDITIONAL COOLANT

The radiator cap should not be removed. When additional coolant is needed to maintain this level, it should be added to the coolant recovery/reserve container (Scheme 6) Use only 50/50 mix of ethylene glycol type antifreeze and distilled water. For the recommeded antifreeze/coolant type (Refer to FLUID TYPES - DESCRIPTION ).

STANDARD PROCEDURE - COOLANT LEVEL CHECK

Note. Do not remove radiator cap for routine coolant level inspections.

The coolant reserve system provides a quick visual method for determining the coolant level without removing the radiator cap. With the engine cold and not running, simply observe the level of the coolant in the recovery/reserve container (Scheme 6) The coolant level should be between the MIN and MAX marks.

Scheme 7

TORQUE

TORQUE SPECIFICATIONS

Scheme 8

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Scheme 13

Scheme 14