Leaky Cargo Box

EASYTRADER

Expert Expediter
I have lots of water coming into my box from above, yet I can't see where its coming from, I m assuming that factory roof sealing has finally crapped out.

It looks to me the only reliable way to fix it is to cut all the rivets, scrape out the old caulking and reattach the sheet metal.

Is this guess correct?

Have you had it done before and if so what's the cost?

I have a 24 foot box.

Thanks

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tenntrucker

Expert Expediter
My old truck leaked, I got the stuff they coat house trailers with and coated my box. I think its called cool seal.

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EASYTRADER

Expert Expediter
I was leaning that way, my roof is a solid piece of sheet metal, so the only place the water can be coming in is at the edge seam? That is a statement and a question.

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Murraycroexp

Veteran Expediter
Don't mess with the rivets. If you're going to pay, go to a trailer shop to repair. If DIY, get that Cool Seal stuff Tenn's talking about. But clean the areas.
 

layoutshooter

Veteran Expediter
Retired Expediter
There is that spray on rubber coating they sell on TV adds and Rust-O-leum makes a version as well. I used it on the top of my sleeper that was leaking. So far, about two weeks since I did it, it is working just fine.
 

guido4475

Not a Member
That spray on sealant dries out after a few months and cracks. I sprayed it around my roof mounted accessories just for future leak prevention and it is all cracked. Buy that stuff from the RV stores sold in a gallon. That's what I originally used and it works great. A little pricey, and nice to work with, brush on, but it works beautiful.

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WanderngFool

Active Expediter
My straight truck was leaking and I found recommendations on RV sites for Dicor roof sealant. It comes in a caulk tube and there's 2 kinds. One is for horizontal surfaces and one for vertical. I bought the horizontal and it really works but it's a little weird. It's not like caulk. It's more like squeezing out a bead of rope. But it does work.
 

spongebox1

Expert Expediter
Black Jack roof sealant, Lowe's or the home depot sells it, flexible and lasts quite awhile, used it on the top of our first truck and its still water tight .

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tknight

Veteran Expediter
Dicor lap sealant works great I have a motor home wouldn't be without it also there is a product called eternabond it's like 4" wide and made from EPDM rubber with a very sticky backing just peel and stick over joints . Sold by the small tool and its not cheap but it's eternal lasting!
 

mugurpe

Seasoned Expediter
I've done this a bunch of times, and also had really confusing leaks. What happens is you have a leak in one place and because of wind, the angle of the truck, or perhaps black magic, the water will run down the aluminum and steel inside the upper parts of the box and then drop down somewhere else. Here's what I do, and it lasts for 5+ years.

Get a real nice carbide scraper, the ones with orange handles they sell at painting stores are good, also get one of the handles that has a bunch of interchangeable blades with different profiles. You'll also want a caulking gun, and atleast one tube of 3M 5200 marine caulk. get a small disposable plastic putty knife or two for smoothing out the caulk if you end up with an abundance.

3M 5200 is serious stuff. It's like a flexible epoxy caulk, it can be removed later but it's not the easiest thing. It can be used like glue, and it stays flexible for a very long times. It's also expensive. You also need to use the whole tube within a short period of time (short shelf life once opened).

I scrape as much of the old caulk out of the joint as I can. often it just peels out. I do the seals at the front corner caps, across top of the front curved piece, the joint between the corner caps and the long rail that goes down the top of the box (tricky) and then 4 feet down the top of the box on either side. If a leak persists later, I often will do another 4 feet down the top on the sides and see if that does it. Never had to go more than half way down a 24' box before I solved all the leaks.

Once you've removed the caulk to your satisfaction, ( it doesn't have to be perfect, just enough clear surface so the 5200 bonds well and so that the 5200 gets into the joint a little), apply the caulk. around the corner caps you'll probably want to apply an abundance to make sure you get a good seal and also sort of "ramp" it up to the edge of the corner caps, this will prevent puddles from being able to form right up against your joint. same in the channel on the sides where the rail meets the corner cap. Also, dab a bit on top of each rivet as sometimes a loose rivet can conduct water down into it and into the aluminum channel below.
 

BobWolf

Veteran Expediter
Owner/Operator
You REALY, dont want to remove the roof yourself the roof holds the walls together like an airplane fuselage if you have the slighyest breaze, the outer walls will will likely colapse and you will have a flatbed.

If its leaking at the pannel seams and allong the top rails, or corner caps pick up a couple tubes of PL 530 Urathane roof sealant your choices of collor are black, black, and black. Once its gunned on it lasts forever make sure the tubes are arround 70 deg F if the sealant is cold below 50 deg it is tough to squeeze out just slip it into your coat before using. it can be messy when its hot 86 deg or over. When its cured its permenant and flexable.

For worn aluminum roofs use the roll on sealers from an RV dealer this will take care of any pinholes in the roof. Make sure you thoroughly clean the surface and spend the couple extra bucks for a flexable urithane based sealer. Water and based sealants are crap.
The most important part no mater what product you use is prep work make high quality repairs if needed, clean surfaces, and follow the dirrections to the letter.

Goood luck and PM me if Iyou have questions.

Bob Wolf
 

pearlpro

Expert Expediter
Way back when I was in the trailer repair biz we used the 3M marine caulk and a Liquid that was brushable, it ws silver when it dried and worked for these mystery leaks, I cant remember the name, but Im sure you can buy it at any trailer repair or RV shop.....WHEN YOU TAKE A ROOF OFF A TRUCK OR TRAILER YOU DONT REMOVE THE CROSS BRACES AS THESE HOLD THE WALLS IN PLACE,

If you have one of these 10,000 candlepower spotlights, in the dark you can shine this around the roof edge and find most leaks, or use a hose and spray the edge as you watch from the inside....we used these spotlites with great sucess.

What ever caulk or sealer you use must stay flexible anything that dries and is ridgid will crack quickly and be useless.
 

EASYTRADER

Expert Expediter
Thanks for all the suggestions,

I'm likely going to TSP pressure wash it and go the elastomeric coating rolled around the edges, that should seal the rivets and edge too.

I tarred the hell out of the leading seam with henrys, as it was the only one that said it worked wet. Of course it hasn't rained on me since.

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RETIDEPXE

Veteran Expediter
I have a 22 ft Supreme box that had water leaking up and down the sides and front. I closed a high pressure air hose in the doors as best I could and had someone pump air into the box while I soaped it up along the top edges and found the aluminum drip rail leaked where it met up with the alum framing along the top of the box sides, caulked it up from the inside with clear silicon and fixed it right up.
 
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