Check Valve: Description and Operation

Fig.2 Front Washer Plumbing:

FRONT CHECK VALVE
Two front washer system check valves are standard equipment on this model, and are installed in the front washer system plumbing. The front check valves are located in the engine compartment in the washer supply hose for each front washer nozzle between the molded plastic hose tee fitting and the washer nozzle. The 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 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 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 prevents washer fluid from draining out of the front washer supply hoses back to the washer reservoir. This drain-back would result in a lengthy delay from when the front 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 nozzle. Also, the front check valve prevents washer fluid from siphoning through the front washer nozzles after the front washer system is turned Off. When the front washer pump pressurizes and pumps washer fluid from the reservoir through the front washer plumbing, the fluid pressure overrides the spring pressure applied to the check ball within the valve and unseats the check ball, allowing washer fluid to flow toward the front washer nozzle. When the front washer pump stops operating, spring pressure seats the check ball 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 optional rear wiper and washer system have a check valve installed in the rear washer system plumbing. The check valve is located at the joint between the rear washer supply hose in the rear body wire harness and the rear washer supply hose in the hardtop wire harness, near the belt line in the left rear corner of the vehicle. The 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 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 body and hardtop sections of the rear washer supply hose. It also 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. Finally, 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, allowing washer fluid to flow toward the rear washer nozzle. When the rear washer pump stops operating, spring pressure seats the check ball in the valve and fluid flow in either direction within the rear washer plumbing is prevented.