Bed Leak

Now that I have my camper shell on I’m trying to seal the leaks in the bed. I sealed under the plastic caps and the sides of the bed are dry as a bone except one spot on the left side towards the rear and was looking for some input on where it could be coming from. Are the bed rails/track system known to leak, they never did on my 20 SR. The right side is completely leak free and so is the left side up to the area in the picture.
Thanks

 

Easiest way to tell would be to have someone spray the outside of the truck with the hose while you sit inside with a flashlight and see if you can tell where its coming from

 

Did you remove the plastic bed rail tops?

Best I found is to take them off and clean the metal with alcohol. Get some 3M foil tape like used for HVAC. I used to extreme temp one.

Apply the tape on top of the metal bed rails. Place the plastic cap onto the rail and slowly push down as to dent the tape where the corresponding holes under the tap are.

Use a razor blade to cut x’s in the foil tape at the indents. Makes pushing the plastic cap on easier.

Use silicone, I used the best I could find. Liberally apply around each of the holes that you have X’d.
About 1 inch from the inside of the bed rail lay a thick bead of silicone the entire length of the tape. This will prevent water from coming down into the bed if there are any small gaps left from the silicone around the holes.

Lay the plastic cap on the rail and firmly press back onto the rail. I used ammo cans to hold the caps down for a few hours to ensure a good smoosh on the silicone.

If you need pics or have any questions feel free to ask.

 

https://www.tacomaworld.com/threads/bed-rail-prep.793449/

Expand post number 6. Courtesy of @tonered

 

I saw a YouTube video of a guy doing what you did but if you don’t mind posting a pic that would be good. I used butyl tape on my SR instead of silicone and it worked good, this time around I used some super thin foam weatherstrip that I had but looks like it didn’t work

 

The butyl tape is better because it's tacky on both sides creating the seal. That's the only stuff my local cap/ tonneau cover place uses. The water is probably coming in on the top of the weather stripping.

 

If you expand post 6 in the link there are pics throughout.

 

@Brex69 - What brand is the cap? Any gaps where the leak is occurring? Have you reached out to the installer of said cap?

 

It’s a used ARE cap off of Marketplace. I do suspect the seal though.
The guy that sold it to me gave me a roll of double bubble seal, but it seemed kind of stiff like it wouldn’t compress well so I bought some ESI seal and am going to replace it this weekend

 

After a really close look it looks like the water was coming in between the steel bed side and the tub. I’m going to pull the tail light out and take a look

 

i sealed my bed rail caps before installing the canopy and have the same leak you do. i believe it is water spray that is coming in from above the fender liner and between the bed. it leaks at that location when i drive on a wet road and when i wash my truck and spray water above the tire.

i thought i read somewhere where someone sealed that area with an expandable spray foam...?

 

I tried the foam from underneath, and it still leaks at places. Also did the butyl tape between the metal bed rail top and the plastic bed rail cover to no avail. When I get back to this project I will start injecting that very permanent windshield urethane into any cracks that continue to leak. I'm very disappointed in Toyota's lack of thought on this issue.

 

You are correct. I have fully waterproofed my bed (because Canopy Camper and I live out of the truck), and there are so many more places for water to come in outside of just the top of the bed rail.

I used Sikaflex along the entire seam between the metal and composite. I also pulled the t-tracks and caulked those bolt holes as well.

It took a long time, but I eventually found every leak.

I have no tailgate sealing experience though, as I have no tailgate.

 

Could you elaborate on the Sikaflex? The company website is daunting.

 

I purchased the 221 version through Amazon.

$14 Sikaflex-221 Multi-Purpose Polyurethane Sealant/Adhesive, 10.1 fl oz, Black – Permanent Elastic Seal, Sandable & Paintable, Non-Corrosive, Bonds to Metal, Plastics & More

https://www.amazon.com/gp/product/B00NW5LWHA?ie=UTF8&th=1

Beware, it is a pain in the ass to work with. Goes on well, but the second it touches anything you don't want it to, it gets messy very quickly. It's not caustic or anything like that, but just messy as all hell.

Does a great job though. Going on two years of direct AZ sun exposure without any noticeable fading or cracking/splitting/peeling.

I have used a black DAP siliconized caulk from HD on less critical areas that I wanted waterproofing, and that is just a bit better as far as workability is concerned.

 

I know my carpet will wick water from the tailgate area all the way to the bed rails …. You could be experiencing the same thing

 

You have to seal under bed rail cap, both inner and outer edges. Water sprays up from tire. Migrates in through holes in top of bed.

 

Where/how do you access this seam?

 

Remove the t-track by unscrewing the T25 (I think) bolts. Once that is out of the way you have access to the entire seam iirc.

 

So you are sealing it from inside the bed? I thought it was sealed from underneath somewhere. Would water, dirt and other crap get trapped between the bed tub and the metal. I have no idea how this is assembled, I guess I should Google some diagrams