Check Valve: Description and Operation

Fig. 2 Wye Fitting And Check Valve:

CHECK VALVE
A washer system check valve is standard equipment on this model. The check valve is integral to the washer nozzle plumbing wye fitting located on the underside of the rear hood panel reinforcement in the engine compartment. The check valve consists of a molded plastic body with a round center section. Three barbed hose nipples are formed in a wye configuration on the outside circumference of the center section of the valve body Within the check valve body, a small check valve operated by a small coiled spring restricts flow through the unit until the valve is unseated by a predetermined inlet fluid pressure. The check valve cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

GThe check valve provides more than one function in this application. It serves as a wye connector fitting between the engine compartment and washer nozzle sections of the washer supply hose. It also prevents washer fluid from draining out of the washer supply hoses back to the washer reservoir. This drain-back would result in a lengthy delay from when the washer switch is actuated until washer fluid was dispensed through the washer nozzles, because the washer pump would have to refill the washer plumbing from the reservoir to the nozzles. Finally the check valve prevents washer fluid from siphoning through the washer nozzles after the washer system is turned OFF. When the washer pump pressurizes and pumps washer fluid from the reservoir through the washer plumbing, the fluid pressure overrides the spring pressure applied to the check valve and unseats the valve, allowing washer fluid to flow toward the washer nozzles. When the washer pump stops operating, spring pressure seats the check valve and fluid flow in either direction within the washer plumbing is prevented.