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FW28z 09-25-2014 08:00 PM

Taillight repair issue.
Today I was checking the taillights in my RV and I had a burned out bulb, so I decided to replace it.

When I opened the tailight bezel, water poured out. It appears the gaskets were not very good, but I found the company that makes the taillight bezels is only about 25 miles from where I live. The manufacturer is Command Electronics, and here is their website:

Command Electronics :: Manufaturers of Lighting for RV, Marine, & Trailers

The bezel I have is model number "003-30", and looks like this:

The ones I have have are the ones with three lights (two red and one backup).

I checked with them and found you can buy new gaskets. They are not on the website but you can call them to order.

The large gasket is part number 140-37b, priced at $2.00.

The small gasket is part number 140-36 priced at $1.00.

You can also buy the entire assembly with the bezel and back plate for $27.00

Their number is 269-679-4011

Well, that is the good news. The bad news is the bezels are recessed in a plywood lined void in the rear wall, and it is wet. Luckily there is no significant damage to the plywood... yet. There was a bit of "fuzz" on the plywood, so there is probably at least some localized superficial damage. So what I need to do is to open the bezels and allow the plywood to dry, then "paint" the entire inside area with epoxy.

That will assure a waterproof void so if the lights leak again, it will not damage the RV end wall.

This may be a winter project as I may have to open up the bezels over the winter for them to completely dry (with a cover of course over the RV).

If any of you have similar bezels, check them and if they leak, perhaps you may want to do something similar to what I am doing.

Photos will be forthcoming...

How is it that something so simple as replacing a taillight can turn into a major project?

Oh, I remember... the only thing that works on a RV is the owner...

rivraton 09-26-2014 01:03 AM


Originally Posted by FW28z (Post 4630)

When I opened the tailight bezel, water poured out. It appears the gaskets are not very good,.

They must have been installed backwards, they are keeping the water in, instead of out...:rolleyes:

FW28z 09-26-2014 01:19 AM

That must be it. Now if I can only get it to rain inside of the bezels, my problem will be solved.

FW28z 09-29-2014 09:34 PM

Here are a couple of photographs.

This is the right-side taillight. When I opened it up, it was all wet inside:

After it dries out, I will seal the wood with epoxy, and new gaskets (they came in today).

And incredibly, when I opened up the left side, I saw perhaps the worst example yet of shoddy workmanship.

If you look at the photo below carefully, you can see a black and white wire coming from the license plate light, and simply run up the outside of the coach, and into the bottom of the main tail light. No effort to conceal it, no effort to waterproof it, and no expense was spared to do shoddy work.

This almost borders on negligence as it is not inconceivable that these wires might short out as they are pinched to the wall by the tail light bezel.

So I re-routed the wire through a bushing, and then epoxied the bushing, and siliconed the wire so it came out inside of the license plate light housing. I had to splice the wire as they did not leave any slack - another example of shoddy workmanship.

This is what should have been done in the first place.

Now I am waiting a day or two for the wood to dry out before I "paint" the wood with epoxy to waterproof it.

FW28z 09-29-2014 09:45 PM

Here is a better illustration of the way the license plate light wires were run by the factory, which is unacceptable.

Illustration on how I rerouted license plate light wires to feed through a grommet, which allows the tail light to seal properly.

malabarbob 09-29-2014 11:59 PM

Agree, gaskets are poor. Thanks for the info. On our first trip noticed water accumulating in the front marker lights. Took apart, dried out, coated contacts and resealed around the lens with RTV. Have to look closely at the tail lights.

JDHoge 09-30-2014 01:33 AM

Thanks for the warning and illustrated write-up! I agree that the work was shoddy and inexcusable. Your repair shows how it should have been done in the first place.

FW28z 10-01-2014 10:39 PM

I finally got the wood dry, and I "painted" the inside of the void with epoxy, which will make a permanent and waterproof bond with the wood.

Shown here is after I epoxied the innards. As well, I siliconed (black silicone) the wire trough so water would not find its way into other areas. I did a test of the wiring trough, and there was no opening in the bottom for a drain, so sealing it at the top was the appropriate action.

I did discover some delamination of the plywood on the passenger side, so I got this taken care of just in time. In the photo above, I was able to insert a screwdriver and wiggle the plywood - definitely delamination.

When I applied the epoxy, I made sure an ample amount oozed into that crack.

After the epoxy and silicone are cured (overnight), I will begin buttoning up the lights. I did buy new gaskets so hopefully I will make the coach water-tight. And if not water-tight, at least any water intrusion will not do any further damage to the wall.

blw2 10-02-2014 01:14 AM

Thanks for the lead on the supplier
You really are a help to this community!

Nice job on that repair. I'm going to keep a closer eye on mine form now on!

Oh and it's sad, but that license lamp wiring isn't much of a surprise...... pretty sad that this is the case.

JDHoge 10-02-2014 01:37 AM

Nicely done! What epoxy paint did you use? I suppose it came with a hardener that you had to mix into a thin base? It seems that this would be superior to spar varnish which is what I probably would have used.

FW28z 10-02-2014 03:53 AM

I didn't use an epoxy paint, but an epoxy adhesive. For most of these kind of jobs, I use West System Epoxy, which is popular epoxy adhesive from the boating world.

However, it takes almost 12~24 hours to completely cure, which makes it stronger as it penetrates the wood more. Epoxy is almost always used in boats for this kind of repair. It's just what I am comfortable with using.

Epoxy is used not only as a glue, but also used with fiberglass or carbon fiber mat to make high-strength/light weight fiberglass. Cheaper boats (and RV's) as well as most "fiberglass" products use a Polyester resin to infuse the fiberglass, while high end boats (such as Hinckley) and other high-value components use epoxy resin. Circuit boards for example is fiberglass mat bonded by epoxy.

For sure, I could have used polyester resin, but epoxy is a higher performance resin and the cost differential is nil for small quantity. Now, if I were fiberglass laminating a 30ft boat, it would take 55 gallon drums of epoxy, at a huge expense.

Unfortunately, West System epoxy does not work very well on vertical surfaces, as the cure time is too long and it tends to run down the side.

So for this job, I used Locktite Heavy Duty epoxy in the 8oz size, which is a general purpose 5 minute epoxy I picked up at my local Menards (regional hardware store like Lowes and Home Depot).

I did not need the penetrating adhesive properties of the West System stuff as this is not a structural repair, but I needed the quick dry stuff to keep it running down the vertical surfaces.

Yes, epoxy comes in two parts; a resin and a hardener. Most epoxy formulations - such as the Locktite stuff I used are mixed equally, but West epoxy for instance is mixed about 3:1 resin to hardener.

No need to thin the epoxy. Thinning it makes it more prone to running on vertical surfaces. It is kind of like painting molasses though. The short 5 minute tack time means it will more or less stay put on a vertical surface.

I use epoxy for all of these kind of things; it is a lot more useful than just a glue. Epoxy is essentially a plastic.

For this application, it is better than spar varnish due to it's adhesive properties which will re-laminate the damaged areas. Also, all you need to apply is one coat. As it chemically cures you can button up the project a lot faster as well. It will still out-gas for awhile though.

The only downside of epoxy is it is not UV tolerant, so if the epoxy will be exposed, it needs to be painted, varnished, or you need to use a UV inhibitor additive. Not an issue here though as it will not be exposed to the sun.

I do also have some CPES, which is a penetrating epoxy that I have left over - again, from boating. I never needed to use it, so it is still new. This epoxy is very thin, and takes about 3 days to dry, so it flows a significant distance through the wood before curing.

It's main purpose is to repair delaminated transoms that have been water damaged. You basically pour it into the top of the delaminated area, and hopefully it will flow down into the wood and fill the delaminated areas, rotted areas, and so on.

It is an effective (sometimes) solution when the value of the boat is not sufficient for a traditional repair.

I should use that stuff for protecting the holes that were drilled into the back side for the mounting of the bezel. However, I am going to try to infuse some silicone grease in the holes, and hopefully that will be enough.

This project got me to thinking though. All of the exposed screws on the RV, whether they were used for fastening the ladder, any of the compartment hatches; basically everything that is attached, were simply drilled into the sides without any underlying protection.

Again in a boat, you would typically "bed" these screws by using a sealant, which will prevent water damage under the screw heads. And I am talking about the upper surfaces, such as bow rails, cleats, etc.

When the fastener is under compression like that, water will wick into it and can damage any underlying lamination. I really don't see a big difference between a RV and boat in this regard.

However, I thought with Thor, they used aluminum tubing for the construction, so why I found plywood in this area is a mystery to me. I think though, that it might just be localized to the tail light area, perhaps to beef up the area for the tail lights.

I know they do that for areas such as the dining table; where it fastens to the wall - there is a piece of plywood backing in the wall.

At any rate, I am going to take a closer look at the other fasteners on the RV.

JDHoge 10-02-2014 11:23 AM

Thank you for the information on all of the products and techniques that you have used. I looked at the West products website and have added it to my bookmarks.

blw2 10-02-2014 01:12 PM

"At any rate, I am going to take a closer look at the other fasteners on the RV."

Remember, you were changing a light bulb!......

My understanding is that they use a tubular aluminum frame, but the walls and such are this plywood core stuff.

& I have always cringed when I see repairmen working on my house and sinking screws into exterior surfaces without bedding them. I guess the compression between the substrate and the thread form some what of a seal, but as you say capillary action can be quite strong.

blw2 10-02-2014 01:20 PM

When working with epoxy I always make a huge mess. I just haven't done it enough, and always find myself in too much of a hurry. I would really be worried about getting it on the outside surfaces and making even a bigger job for myself.... one that I couldn't fix!

FW28z 10-08-2014 01:25 PM

Well, the good news is that after a monsoon the other day, I opened up one of the light fixtures, and nothing was wet inside. The silicone (not a sealant, but a grease) looks to have helped in creating a barrier to the water. Some of the silicone is on both the gasket and rear wall of the coach, so I got a good seal I guess.

FW28z 10-08-2014 01:33 PM


Originally Posted by blw2 (Post 4783)
When working with epoxy I always make a huge mess. I just haven't done it enough, and always find myself in too much of a hurry. I would really be worried about getting it on the outside surfaces and making even a bigger job for myself.... one that I couldn't fix!

Epoxy will definitely stain gel coats. Gel coat is actually a bit porous, and if you get any epoxy on it, it will be a permanent yellow.

I always blue-tape mask off any areas I am working on, and then only mix up enough epoxy to do the task at hand.

Believe me, I am pretty sloppy when it comes to epoxy (which is why I know about the staining). But over the years, I have come to have an agreement with the stuff... plus I use gloves.

I made some speaker "balls" once for my boat, and I fiberglassed them with epoxy resin:

The red stuff is the epoxy. This is when I learned to wear gloves.

FW28z 10-08-2014 02:06 PM


Originally Posted by blw2 (Post 4782)

My understanding is that they use a tubular aluminum frame, but the walls and such are this plywood core stuff.

When I visited the Thor plant last year, I did not see any plywood in the exterior construction. But I did not get the "full" view of the wall construction as they had quit for the day when we visited that area.

The walls were square tube aluminum welded together with foam core between them, with a sheet of fiberglass panel on the exterior, and a sheet of luan (Philippine Mahogany) on the interior - all glued and pressed together on an immense press.

All of the fastener locations used steel backing plates, so most of the screws went into sheet steel rather than the aluminum channel.

However, I was able to obtain some sidewall drawings from Thor, and I see that there is a bit of plywood in areas that probably need more stiffening, such as where the table mounts to the wall, the sides of the front berth overhang, etc.

So it is likely that the plywood is minimal (at least in the "shell"), and the plywood I encountered is likely "local" to that area.

Also, per the drawings I see, the roof is plywood screwed down over the aluminum square tubing.

Unfortunately, though, I did not get a drawing of the rear wall. I asked Thor for it, but so far, I have not heard back from them.

blw2 10-08-2014 07:29 PM

I just went to look at mine. there's moisture in there for sure.
Now that I know what's behind there in the name of raw wood, I'll be pulling of the lights ASAP
Ugh.... just what I didn't need.... one more thing to do this weekend!

Sometimes I just get irritated that I spent so much for so little .....

Sometimes I'm not so sure if I'll be buying another THOR product ever..... and I'm not so sure that if they even knew that that they would really care.

FW28z 10-08-2014 07:52 PM

Well, after fixing it, at least you will know your back wall won't rot away.

blw2 10-09-2014 04:02 PM

Not having removed my lamps to see what I'm dealing with....I'm thinking this through a bit.
My thinking is this.....
An epoxy adhesive can be fairly brittle.
Also, it will not have the same coefficient of thermal expansion as the wood
and will cure before it can really penetrate the wood deeply.

So I'm wondering if long term the epoxy could fail in places and then the water would get behind it. Seems that once the water is behind it there would be little chance for it to ever dry.

So I wonder if there aren't other treatments that might serve better than fast cure epoxy.....
I'm thinking of
linseed oil
tung oil
Thompson's water seal (or similar)
never wet
copper green preservative
or maybe these products such as Rustoleum's Restore deck finish

They might likely require periodic re-treatments
and for the oil based sealants this would be much easier....

but maintaining a decent seal around the fixture
and maintaining a weep hole
might serve to keep things in order????

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