Cummins 4BT 3.9 and 6BT 5.9 Thermostats are small but essential components in a truck’s cooling system. It serves as the gatekeeper for coolant flow to regulate the engine’s temperature. When the engine is cold, the thermostat remains closed, preventing coolant from flowing through the radiator and instead keeping it circulating within the engine block to warm it up quickly. Once the engine reaches its operating temperature, however, the thermostat opens up to allow coolant to flow through and dissipate heat via the radiator. If a faulty or stuck thermostat prevents proper coolant flow, it can lead to overheating and potential engine damage. Regular maintenance of this part can help ensure the proper functioning of a truck’s cooling system.

Maintain the cooling system in Cummins B-Series engines with thermostats from Hawks Parts. Correct regulation of temperature is vital to the operation of 4BT and 6BT engines, so when it’s time to replace the thermostat, check out our catalog. We have 5.9 and 3.9 Cummins thermostats in Genuine and Aftermarket.

Malfunctioning thermostats can lead to irreversible damage in the cylinder head. Avoid a complete rebuild by replacing the thermostat in your Cummins 3.9 and 5.9L engines during routine maintenance.

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