GM 6.5L V8 – Water Crossover and Thermostat

Coolant exiting each cylinder head moves through the water crossover mounted to a common outlet. The water crossover uses a bolt and stud to retain it to each cylinder head, and a gasket provides sealing (see Figure 4-6, view A).

The water crossover contains a thermostat that sends coolant to the water pump through a hose during engine warm-up operation. A bolt and stud hold the thermostat housing to the water crossover, and a gasket seals the flange (see Figure 4-6, view B).

When the coolant reaches a temperature of 190° F (88° C), the thermostat begins to close a bypass passage to the water pump and open a passage through a hose to the radiator (see Figure 4-7). At 215° F (102° C), the bypass passage is fully closed and full flow is allowed from the engine to the radiator. The full-blocking function of the thermostat is required to provide maximum cooling system efficiency.

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