Keeping you Ready for the Road Ahead , the Dorman Heavy Duty Pressurized Coolant Reservoir is made of durable plastic and is built as an overflow for storing the expanded coolant produced by engine heat. When the engine cools, coolant then retreats back into the radiator. The signs of a failing coolant reservoir may include a pool of coolant under the truck, suggesting a crack or leak in the tank, an overfilled reservoir, white smoke from the exhaust, and oil in the coolant reservoir. If your heavy duty truck is showing any of these signs, this heavy duty coolant reservoir replacement boasts of durable construction that is able to withstand both heat exposure and vibration. Dorman has a distinguished reputation in the heavy duty truck and trailer aftermarket, manufacturing a variety of parts for a complete repair. Through advanced engineering, Dorman successfully checks into today’s most common failures to figure out the why, ultimately delivering modern solutions that not only match OEM parts, but solve known issues. FleetPride is your First Click in Heavy Duty .