Stant® 15259 - Engine Coolant Thermostat & Water Outlet Assembly

The thermostat blocks the flow of coolant between the engine and radiator until the engine reaches a predetermined temperature, then it opens as required to allow coolant circulation and keep the engine temperature within the specified operating range. A typical thermostat has a wax filled copper housing called a “heat motor”. As the engine coolant warms, the wax melts and expands, pushing against a piston inside a rubber boot, forcing the piston outward and opening the thermostat. The thermostat begins to open within 3 or 4°F of its rated temperature and continues to open according to the engine’s cooling requirements, becoming fully open at about 15-20°F above its rated temperature. If coolant temperature begins to drop, the wax element contracts, allowing spring tension to close the thermostat and decrease coolant flow.

A thermostat can fail by sticking in the closed or open position. If the wax element becomes damaged, the thermostat can prevent the flow of coolant to the radiator and cause the engine to overheat. If the return spring breaks or debris prevents the thermostat from closing, the steady flow of coolant may overcool the engine, causing poor heater performance, increased emissions and reduced fuel economy. If you’re in need of a new thermostat, don’t settle for 2nd best, get a Stant, the world leader in thermostat engineering.

The heart of every Stant thermostat is the patented ELAC heat motor, which delivers consistent and precise response to cooling system needs. The ELAC heat motor is powered by a precisely formulated thermal responsive wax pellet in a heat conducting copper cup equipped with a stainless steel piston inside an elastomeric boot. The exact length of the piston assures the prompt and precise operation of the thermostat valve. Each heat motor is 100% calibrated to guarantee quality and performance, then it’s placed in a stainless steel valve, flange, bridge, and spring assembly.

If you’re looking for the highest flow rate of any thermostat on the market, choose the Stant SuperStat thermostat. The SuperStat uses a high flow venturi for maximum cooling capacity during high temperature, high load operations, and employs a unique Weir Valve for precise flow metering during cold, light load operation to ensure stable temperature control under all conditions. Unlike conventional thermostats that continually cycle open and closed to maintain operating temperature, the SuperStat has a unique V-notch, non-linear design that reduces cycling by precisely metering the coolant. And if you want the exact OEM design in a replacement product, Stant has what you need with the XACTstat thermostat, which is manufactured with all the features of the original equipment thermostat.