A current discussion about tiny bubbles on an interior ceiling found here-
Bubbled interior roof
reminded me about my problem.
I had/have bubbles on an interior wall near the top in the rear.
I discovered that several clearance lights were leaking.
Unless they have changed-- these clearance lights have a tiny notch in
one side of the base where the lens snaps onto the base.
This notch is supposedly to let any water that manages to get inside leak
out the notch. This notch should be facing DOWN when installed.
The problem seemed to be that when my trailer was built they didn't
pay any attention to orientation of that drain notch.
My clearance lights and marker lights both the high ones and the ones
along the sides on all corners were just randomly installed.
About half of them were right side up and half upside down.
The installer obviously just grabbed each one and slapped in on there.
They were well caulked where the base met the wall but the lens leaked
and that water was able to half fill the lens and then enter tru the wiring hole!!
I removed each lens and saw obvious high water marks half way up
The strange thing was this high water mark appeared in lights that
were right side up (notch on the bottom) the same as those with the notch on the top.
My fix was to remove each lens and clean the dirty inside and rim and then
carefully apply a thin bead of caulk all
the way around the rim of the base so the lens is caulked in place.
I believe this has stopped them from leaking.
Also the front top clearance bases had only been caulked along the
top and sides. This would supposedly let water that got behind the
base leak out the bottom. When I'm driving in rain the hurricane wind
hitting the front of my trailer forces the rain to run UP the front of my
trailer so it was getting UP under these top 5 lights!
I sealed them all the way around AND then sealed the lenses in place.
This process took at most a couple hours but it NEEDED to be done.
Just a heads up to you all.
IF you pull off a clearance/marker lens and see a dirty water line inside-
you need to seal it!!
Several of mine also had rusty mounting screws- another sign they were
You can use clear caulk but I used white because that's what I had.
I used a thin bead around the rim of the base and you have to look
VERY closely to see it's white and not clear. Can't tell at all from
a few feet away. (Remember the bases are white.)