Control rod sinks, more often called pop-up sinks, use a remote lever that operates an integral stopper, which raises to allow water out of the sink and in its lowered position keeps water in. The mechanism between the lever and the stopper is not connected to the water supply, so the only leaks associated with using control rod sinks are water in the sink escaping when this is not desired or water leaking from the drain when the sink is intentionally emptied.
Countless unique control rod designs have been manufactured, but they almost all share the same basic components: An actuating lever above the sink is connected to the eponymous control rod, which runs horizontally down the back of the sink -- usually parallel to its center line -- to slightly below where the drain is attached to the underside. The bottom of the control rod is attached to a second lever, a horizontal pivot arm. This arm passes through a pivot nut on the side of the drain, into the drain itself, where it joins the bottom of the stopper. When the top lever is raised, the control rod is lowered, the outside of the pivot arm is lowered so the inside is raised, and the stopper is raised as well. At this point the sink should drain. When the top lever is lowered, the control rod is raised, so the outside of the pivot arm is raised, and the inside drops; the stopper drops as well. At this point the sink should hold water.
Addressing the Problem
Control rods and the mechanisms they operate seldom break. Issues are more frequently caused by seizing, a result of inadequate lubrication in a steamy atmosphere. Learn how your particular model works then apply the generalized advice to the specific design.
Leaking Out of the Sink
The part of the control rod assembly that most frequently seizes is the pivot nut. Get below and behind the sink, locate the pivot nut and spray it with penetrating oil. Wait the period of time recommended by the oil manufacturer then operate the control rod several times; it should regain its full range of motion, and the leak will be fixed. While below the sink, check the firmness of the pivot arm nut; it should be just tighter than finger-tight. If it can be moved with your fingers, it is too loose and is unlikely to hold the stopper firmly in place, either open or closed. Tighten the nut to just beyond finger-tight with an adjustable crescent wrench.
Water Leaks Behind the Sink
If water is leaking from behind the sink when the stopper is pushed up, the culprit is the pivot arm ball. Use the wrench to turn the pivot arm nut counterclockwise until it releases then carefully remove the washer from behind it and the ball nut that holds it in place. Grease the ball with plumber’s grease or petroleum grease. Reassemble the pivot arm with a new washer. Again, tighten the nut to just beyond finger-tight.
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