W 250 Pickup L6-359 5.9L DSL (1989)
Thermostat: Description and Operation
The thermostat controls the coolant temperature. When the coolant temperature is below the operating range, coolant is bypassed back to the inlet of the
water pump. When the coolant temperature reaches the operating range, the thermostat opens, sealing oft the bypass, forcing coolant to flow to the
radiator.
CAUTION: Never operate the engine without a thermostat. Without a thermostat the path of least resistance for the coolant Is through the bypass to the
pump Inlet. This will cause the engine to overheat.
An incorrect or malfunctioning thermostat can cause the engine to run too hot or too cold.
