Ensuring you are Ready for the Road Ahead , the Dorman Heavy Duty Pressurized Coolant Reservoir is made of durable plastic, built as an overflow for storing the expanded coolant produced by engine heat. When the engine cools, coolant retreats into the radiator. Indicators of other engine issues being seen within the coolant reservoir include an overfilled reservoir, white smoke from the exhaust, and oil in the coolant tank. The signs of a failing coolant reservoir may include a pool of coolant under the truck, suggesting a crack or leak in the tank. If your heavy duty truck is showing any of these signs, this heavy duty coolant reservoir is built to be a quality replacement option, able to endure harsh under-hood temperatures. 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 .