SOLVED: Front cap leak...

CPDDet

Active Member
Had my 2017 Sundance 3100 CK 5th wheel parked in Florida for 3 months. When it came time to leave I raised the front end to get it on the hitch and had some water run out from where the bottom of the front cap attaches to overhang. Obviously the caulking in this area is bad, but at least it let the water drain out.

Since the unit was parked for 3 months I'm assuming the area where the front cap attaches to the roof is the issue. No way of knowing if any water damage has occurred under the cap, but no visible water damage on the inside of the front sliding door closet. I see others have had similar problem with this due to loose / stripped screws that attach the front cap to the roof.

Going to get a good look at it today but thought why not check all the screws and then use 4" wide Eternal Bond Tape to overlap and cover the entire seam. Then remove the old caulk along the bottom seam and re-caulk that.

Any thoughts on my idea?
 

danemayer

Well-known member
Re: Front cap leak...

I've had Eternabond across front and back where the cap meets the roof for 7 years.

Water can migrate and take unexpected paths. Don't overlook marker lights, scare lights, vents on the roof, vertical caulking on the cap, etc. etc.
 

CPDDet

Active Member
Re: Front cap leak...

Thanks Dane,

I will, of course, check the area around the front AC and vent pipes. As you say, water can migrate and be tricky but I think the front cap seam is a good place to start. Hopefully there will be an obvious problem when I get up on the roof.

Going to remove all the old caulk on the bottom seam and raise the front end to let any remaining water drain out (if there is any) I'll leave it that way at least until tomorrow in an attempt to help dry things out. In the meantime Ill work on the roof seam.

Dave
 

wdk450

Well-known member
Re: Front cap leak...

It seems like I have read of water in the front cap not from usual leakage, but assumably from air condensation. This might take a lot of thread searching to find these posts, so hopefully the people who had this problem will chime in. Florida this time of year has a LOT of water in the air.

Other threads mention checking the proper water sealing of the marker lights.

On Edit: Here is one of those posts about condensation: https://heartlandowners.org/showthread.php/69645-Water-leaking-from-pin-box-front-cap
 

CPDDet

Active Member
Re: Front cap leak...

Actually we left Florida on April 1st. But February was the hottest on record down there and during our 10 week stay there were a few strong thunderstorms.
Arriving back in northern Illinois on April 20th (we stopped in Texas and Oklahoma to visit family) I put the camper in outside storage where it has been sitting. The weather here during May was warm with several days into the 90's with high dew points. There were a few heavy storms as well with high winds and hail. When I went out to the storage area yesterday, I again noticed a small amount of water dripping from the bottom front cap seam. So I'm guessing it could possibly be condensation but could also be a leak.

This morning I took the camper to a local county campground, to check things out.

Well, the roof / front cap seam looks good. I removed the trim along the bottom of the front cap. There is a rubber molding over an aluminium strip, one on each side, that runs from the pin box to the edge of the outside walls.

Each of the two aluminium strips have about 10 self-tapping screws that hold it, and the front cap, to the black plastic which covers the underside of the overhang. Strange thing is, all the screws, except for the the last one closest to the outside wall (which is much longer), hold the strip and the front cap to the black plastic but don't hold these to the camper itself. The whole thing flexes in the center when pressed on. Doesn't seem to be any structure to attach to.

When looking at the front of the camper I have only noticed water dripping from the strip that runs from the pin box to the right outside wall. This aluminium strip showed signs of oxidation and rust marks under the screw heads. No so on the left side strip, that looked pretty clean.

I managed to get a good amount of separation between the edge of the front cap and the black plastic, enough to get a flashlight in there for a peek. On the right side there was some moisture, not standing water, but a damp spot about the diameter of a coffee mug. This was about 8 inches back from the edge of the front cap, and I could just get my hand in there to feel it. This is also the low point between the pin box and wall.

I could also see some of the insulation on the inside of the front cap which looked OK and the few screws I could see toward the front of the cap were still clean and shiny.

I cleaned all the surfaces of the black plastic, front cap,aluminium strip and plastic cap molding. Ran the screws back in and replaced the cap molding on the aluminum strips.

Its now ready to be re-caulked. But my fear is if it's not condensation and I haven't found the leak, I will be trapping the water in the bottom of the front cap. So I'm going to wait on the caulk and see if I can replicate the problem by running water on the roof near the front cap / roof seam and, if that has no effect, give the marker and courtesy lights on front of the cap a good spraying.

Dave
 

CPDDet

Active Member
Re: Front cap leak...

Problem solved!

I went back to camper this morning with the intent to remove the rubber cap molding, screws and aluminum bracket along the bottom seam one the side where I was experiencing the dripping. Then spreading the black plastic from the front cap and wedge it open so I could check inside after hosing down the marker / courtesy lights and top seam.

We had some light showers overnight and when I started to remove the rubber cap molding I noticed there was moisture all along the seam. The aluminum strip was wet but there was no standing water or moist area inside the cap where I noticed it yesterday. Thought it was puzzling but went on with the plan.

I wedged a 2” wide roll of tape in the opening and proceeded to hose down the front lights. Checked inside the cap and found nothing, bone dry. Then I went up on the roof and gave the top seam a good soaking. Checked inside the cap and still bone dry.

BUT I noticed water now dripping from bottom seam on the other side of the king pin. I removed the rubber cap molding on that side and found it soaked. Pulled all the screws and the aluminum strip, which was also wet, and peeked inside the cap; sure enough, there was a small wet spot about 5 inches back from the seam.

I got the flashlight, wedged open this side and got a good look. The only water track to the wet spot was coming from the edge of the cap. Then I realized that the side I had wedged open had changed the shape of the underside enough that the water didn’t wick down to the edge of the cap. But the side that was still screwed together allowed the water to run down the front cap and under the overhang all the way to the seam where the caulk along the rubber cap molding had failed. That was why the side I first disassembled was wet from the overnight rain; the water was running along the underside and getting under the rubber cap molding. The underside of my front cap isn’t perfectly flat from one side of the camper to the other. It has a bit of a dip down about halfway between the outside edge and the king pin on both sides. This downward dip was allowing the water to run down the front cap, under the overhang and under the rubber cap molding. Once the water got to that point it was following the downside slop of the “dip” , moving back under the cap and pooling several inches back, at the lowest point of the “dip”.

I dried everything out and replaced the aluminum strips, then ran a small bead of caulk along the front and back edges. Then I replaced the rubber cap molding and caulked the front and back edges of that as well.
 
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