Check Your Marker Lights

Question

Somewhere on this great forum I read marker lights on trailers and fifth wheels were the biggest sources of leaks.

Having completed my roof upgrades with Eternabond tape, this year I decided I would pull a marker light out and check it to see how it was sealed.

To my surprise, the caulk sealing the marker light was silicone. And had started to turn loose after nearly four years of happy use. Too, our trailer must sit outside uncovered.

Also to my surprise, the metal screws holding the fixture were starting to rust, indicating that there has been moisture getting by the silicone sealant.

So I have begun taking off all the marker lights and resealing them. I use Doublestick Eternbond on the screwholes and large hole for the electrical wires. Then I used Geocell Proflex as the final top seal and side seal of each marker light.

Also, while reassembling the marker lights, I opted to use stainless steel screws, instead of the zinc coated steel screws. My trailer has eleven marker lights on it. So far, about half of the screws have had rust on them.

So do not take for granted your marker lights are 100% sealed like me.

coolestdude · Answer

Thanks for the tip! How old is your TT ? Happy Trails!

tecmike · Answer

Our travel trailer will be four years old this fall. We have pulled it a lot through may states. Happy times!  Been a wonderful little trailer, no problems other than those self inflected by me!

diskdoctr · Answer

Hi Mike,Be careful when working with lights mounted to aluminum skin campers. Often the aluminum is used as a ground for the lights. If the screws, metal frame of the light, and the camper skin do not make good conduct...poor, unreliable, or no lights :(A tip: Take about an inch of multistranded wire and skin all the insulation off of it. Put it into the hole in the camper wall and through the hole in the light, then put the light in place and run the screw in. Ideally about 1/8-1/4" will be left to wrap around the screw head, just be sure it doesn't touch your hot or bulb, just the grounding plate.Of course you can seal it up, then. The wire helps the screw get a fresh bite and helps with grounding all around.And, yes, good advice to check these. MOST of the screws I have pulled out on many campers and trailers are rusty :E (When cold outside, the screws will conduct the cold along its length inside the wall and if it is warm/humid enough, it can condense. (Same with your house insulation and wall sheathing, ref:thermal break)

bartlettj · Answer

If the screws are normally covered by something, I like to use steel screws- that way I can tell if water is getting in there and causing the rust. They're a telltale.

tecmike · Answer

During the marker light rehab, I have truly found that silicone is your worst enemy, as mentioned in some other threads and post on this forum. It is extremely hard to completely remove.

As mentioned above, our trailer is four years old and some of the silicone caulk was starting to turn loose on the edges, which I suspect allowed a little moisture to penetrate the joint between the marker light housings and the trailer's fiberglass walls and ends. Not sure if UV rays caused the silicone caulk to break down or just continued movement of the trailer over many miles.

I believe the Proflex is a much better product, IMO, and will hold up better.

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Check Your Marker Lights

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