Leaky Portlights

    The aluminum-frame, non-opening portlights that were popular some years ago eventually develop leaks, and smearing sealant around the outside of the portlight assembly to reseal it is ineffective. Despite multiple layers of sealant, the portlights can still leak. It is best to remove the portlight, clean it, and remount it, all of which can be done in a few hours (with the materials in hand).
    When you reinstall the portlight assembly, apply sealant to the area between the frame flange and the doghouse. After applying a bead of sealand, screw the trim ring in place. Work carefully to control sealant ooze, and cut away the excess after the sealant cures. If you use a 3M product, choose #4200 instead of #5200 for easier future removal.


    The aluminum frame that supports the portlight's glass is held in place by a trim ring that's attached to the frame assembly with screws (Fig. 1). The rubber or plastic strip that fits between the trim piece and the frame is usually decorative and should be easy to remove.
    The leak is the primary problem, but you may have to deal with multiple layers of sealant first. Remove the mounting screws, and use a putty knife to gently pry the trim ring outward. Slice through the caulk with a sharp blade, being careful not to cut yourself - patience, not power, yields the desired results. Once the inside trim rign is off, repeat the process to remove the entire portlight assembly.
    Inspect the outside of the portlight mounting hole and the frame/window assembly. If a dirt pattern runs to the edge of the cutout, you've found a leak. For frame-to-house leaks, clean off the old material and recaulk and remount the portlight. If the portlight hole is okay, examine the vinyl gasket between the glass and the frame (Fig. 2). Over time the gasket can shrink, creating a large gap between the ends. If the gasket seems sound and the only problem is a small gap that admits water, use a dab of silicone sealer to close the hole. If the gasket is bad, it's not always easy to locate a replacement, so you may have to make your own (or replace the portlight.
    If you decide to take the frame apart to replace the gasket, look for a seam at each end of the frame. Portlight frames are usually made in upper and lower halves and are secured by two metal joiner plates and pop rivets (Fig 3). Drill off the rivet heads, then use a small punch to knock out the rivet. After replacing the gasket, pop-rivet the assembly back together. You don't have to use sealand as the gasket seals the glass and frame.