Check Valve: Description and Operation
FRONT CHECK VALVEFig.3 Front Check Valve:
A single front washer system check valve is standard equipment on this model, and is installed in the front washer system plumbing. The check valve is integral to the front washer nozzle plumbing wye fitting located in the cowl plenum area beneath the cowl plenum cover/grille panel near the base of the windshield. The front check valve consists of a molded plastic body with a raised arrowhead molded into its center section that indicates the direction of flow through the valve, and three barbed hose nipples formed in a wye configuration on the outside circumference of the center section of the valve body. The front check valve cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The front 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 front washer supply hose. It 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 front washer nozzles, because the front washer pump would have to refill the front washer plumbing from the reservoir to the nozzles. Such a drain-back condition could also result in water, dirt, or other outside contaminants being siphoned into the washer system through the washer nozzle orifice. This water could subsequently freeze and plug the nozzle, while other contaminants could interfere with proper nozzle operation and cause improper nozzle spray patterns. In addition, the check valve prevents washer fluid from siphoning through the washer nozzles after the washer system is turned Off.
Fig.4 Front Check Valve:
When the front washer pump pressurizes and pumps washer fluid from the reservoir through the front washer plumbing, the fluid pressure unseats a diaphragm from over a sump well within the valve by overriding the spring pressure applied to it by a piston. With the diaphragm unseated, washer fluid is allowed to flow toward the two washer nozzles. When the front washer pump stops operating, the spring pressure on the piston seats the diaphragm over the sump well in the valve and fluid flow in either direction within the front washer plumbing is prevented. The front check valve cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
Fig.3 Rear Check Valve:
REAR CHECK VALVE
Models equipped with the rear wiper and washer system have a check valve installed in the rear washer system plumbing. The rear check valve is located in the engine compartment near the back of the right front wheel house, where it is installed between the engine compartment and passenger compartment body sections of the rear washer supply hose. The rear check valve consists of a molded plastic valve body with a raised center section that is tapered in the direction of the flow through the valve. A barbed hose nipple is formed on each side of the raised center section of the valve body. Within the rear check valve body a small check ball is held against an integral valve seat at one end of the valve by a small coiled spring. The rear check valve cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The rear check valve provides more than one function in this application. It serves as an in-line connector fitting between the engine compartment and body sections of the rear washer supply hose. It prevents washer fluid from draining out of the rear washer supply hoses back to the washer reservoir. This drain-back would result in a lengthy delay from when the rear washer switch is actuated until washer fluid was dispensed through the rear washer nozzle, because the rear washer pump would have to refill the rear washer plumbing from the reservoir to the nozzle. Such a drain-back condition could also result in water, dirt, or other outside contaminants being siphoned into the washer system through the washer nozzle orifice. This water could subsequently freeze and plug the nozzle, while other contaminants could interfere with proper nozzle operation and cause improper nozzle spray patterns. In addition, the rear check valve prevents washer fluid from siphoning through the rear washer nozzle after the rear washer system is turned Off.
When the rear washer pump pressurizes and pumps washer fluid from the reservoir through the rear washer plumbing, the fluid pressure overrides the spring pressure applied to the check ball within the valve and unseats the check ball. With the check ball unseated, washer fluid is allowed to flow toward the rear washer nozzle. When the rear washer pump stops operating, the spring pressure seats the check ball in the valve and fluid flow in either direction within the rear washer plumbing is prevented. The rear check valve cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.