What Causes a Dodge Caravan to Overheat?

The No.1 cause of a hot engine is low coolant level. Check your coolant when the engine is cool, and top it off as needed. If your coolant is low, check all cooling system components for leaks, including the heater core hot-water lines, and repair them as necessary. Sometimes, after adding coolant during a maintenance or service, an air bubble can become trapped within the cooling system, causing an air lock to form that prevents the coolant from circulating and carrying off waste heat properly. You can evacuate the air from the system using the Dodge Coolant Refiller, part No. 85-15-0650, and a source of compressed air. Top off the coolant in the reservoir after evacuating the air.

Various mechanical failures can cause your engine to overheat. A failed radiator cap will prevent the system from developing the pressure necessary to raise the boiling point of the coolant, leading to coolant loss through the reservoir. Loss of circulation due to a bad thermostat, degraded radiator hoses, damaged or clogged radiator or a loose water pump drive belt can also lead to overheating. Sometimes the air movement needed to effectively carry off heat from the radiator is insufficient. This can be caused by debris, such as bugs and leaves, clogging the cooling fins of the radiator, or a failure of your cooling fan. The electric cooling fans can fall prey to failures in the fan motor, bad temperature sensors, blown fuses and bad connections. The Caravan is equipped with two cooling fans in an integrated unit, and neither are sufficient to cool the engine by itself, so if one of the fan motors goes bad then both fans must be replaced.

The 2.4-liter and optional 3.3-liter engines in the Caravan can suffer catastrophic internal damage if they are allowed to run when overheated. Neither engine has a history of recalls, TSB's or persistent customer complaints pertaining to overheating, so there seems to be no inherent cooling problems with these engines. But when any engine severely overheats, oil viscosity breaks down and the machined parts in the engine can expand and become larger than their bores. The valves can stick in the guides, preventing the springs from retracting them and allowing the valves to contact the pistons, damaging both components. As the pistons swell, they will begin to gall, or transfer material from the piston onto the cylinder wall. This material can then destroy your rings and further damage the piston as it reciprocates in the cylinder. If allowed to reach high enough temperatures, or if cooled too quickly, the head can expand and crack, rendering it useless. Be sure to attend to any cooling issues in a prompt manner to avoid the engine-killing effects of overheating.

Dodge recommends that you use Mopar Antifreeze/Coolant MS-9769, or an equivalent ethylene-glycol coolant, mixed in a 50 percent solution with distilled water. Avoid using propylene-glycol coolant, and never mix coolant types or colors. The total cooling system capacity is 13.4 quarts for models without the auxiliary heater, and 16.3 quarts for models equipped with the auxiliary heater.