GM 6.5L V8 – Radiator System

The radiator is a heat exchanger assembly of finned metal tubing connected to end tanks and is mounted in front of the cooling fan assembly (see Figure 4-10). One of the radiator end tanks has the engine oil cooler mounted inside it, and the other end tank contains the automatic transmission oil cooler.

Airflow caused by vehicle movement and the operation of the cooling fan removes heat from the coolant flowing through the radiator. The radiator has a steady flow of coolant from the engine through the heater core system at all times, and also has direct flow from the engine through the water crossover when the thermostat is above 190° F (88° C).

The radiator has a pressure/vacuum relief valve in its fill cap, and the cap fitting has connection to a remote reservoir. The radiator cap limits cooling system pressure to a maximum of 15 psi.

When the pressure valve of the radiator cap opens, excess pressure and coolant are exhausted to the reservoir (see Figure 4-11). When the vacuum valve of the radiator cap opens, coolant travels from the reservoir into the radiator.

One of the end tanks has a fitting for the probe used in a low coolant warning lamp circuit (see Figure 4-12). The monitoring circuit is located in a module mounted behind the instrument cluster.
The low coolant circuit has the ability to detect the absence of liquid in the radiator tank at the probe location and complete the LOW COOLANT warning lamp circuit to alert the vehicle driver (see page 8-37 for more information).

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