Seal bed rail caps

Hello,
The shop that will install my ARE canopy warned me that some taco owners have water leak between the plastic bed rail cap and the bed side walls. They indicate that low pressure sucks water in when the truck is moving fast.

The rail caps come off easy enough...

What would you use to seal this area? I'm considering weather stripping and some kind of sealant like silicone caulk or RTV.

Thanks,

David

 

subbed, wasnt aware this was an issue.

 

I'm pretty sure there is a weatherstripping under there already. I would stay away from the silicone and maybe add a second strip of foam. More likely the leak is happening at the front of the bed where it is about 1" lower than the sides. I've played hell to get that sealed especially at the corners.

 

that bulkhead area is def a bad design

 

I found no foam on mine; just hard plastic sitting on painted metal. My concern with weatherstripping is that the underside of the cap is not flat. The horizontal top of the cap sits on a series of vertical "walls" that actually rest on the bed itself. Those vertical members are pretty sharp, and might act like cookie cutters and saw channels through the weatherstripping eventually.

I've got a month or so before the canopy comes in; I'll press them for more details.

 

When I first installed my cap I got light leaking when going through the auto car wash.
I went and did a 3 step process to seal the cap up.
1-I bought a big tube of some type of silicone at home depot. (Sorry I don't remember wht type). I removed the plastic caps on top of the bed rails and laid down a real heavy bead the length of the rails, then reinstalled the plastic caps.
2-i had a roll of 1" wide by 1/2" thick foam on a roll from a previous project. I took this and applied it the length of the underside of the cap perimeter. When I reinstalled the cap, I had 3 friends help.lift the cap, and we placed it straight down on the correct spot, rather than sliding it.
3-I bought a super thick gasket on Amazon.
https://www.amazon.com/gp/aw/d/B00C0WVV72/ref=yo_ii_img?ie=UTF8&psc=1
This was applied to the front edge of the cap, where there is a large gap on the truck.

Since applying these water proofing techniques I have had ZERO leaks all summer. I wash my truck nearly every day at the touchless car wash on my way home from work. I have yet to see any leaks when I open the cap at home after.

 

Thanks for the info! Sounds like you've got it nailed.

 

@HawkShot99

Did you ever have any issues with the shell leaking around the front corners? Did the thick gasket fix them?

That's where I'm mostly getting my problems and my installer said there is nothing they can do, "It's a Toyota problem". I took my truck back to them and they filled up those gaps with some serious silicone, it's supposed to rain tonight so we will see if that works. If it doesn't, I'm going to take take it back to them and have them follow your process (I should have done step 1 before I originally had the top installed)

 

I did have some light leaking in the corners but not super heavy. I have had no leaking since my seal job.

 

Subd. I guess I’ll be giving this a shot before I put mine on. Just got to find out ho2 easy those side caps come off!

 

Very. At both the cab side and the tailgate side is a plastic tab on the rail cap. It hangs down into the bed and is secured by a plastic push piece. Use a small flat head screw driver to lift the push piece, and pull out.
Using more force then you think start lifting the rail cap at the tailgate end. There is about 8-10 tabs that stick down into the sheet metal.

 

Just saw you have a 3rd gen. Not sure how accurate my directions are.

 

Thanks hopefully someone will chime in. I know there’s a vendor that sells steal replacement caps. Hopefully they have a video

 

This is essentially what you're up against...

https://ae01.alicdn.com/kf/HTB1rl.S...dy-b-font-Trim-font-b-Panel-b-font-font-b.jpg

Start at the back end and pry up a little bit.

When you hit something that feels like a fastener, push towards to the center of the cap (from the inside and outside of the bed) to pop the fingers free.

A few things you'll hit are plain pillars that do nothing but align the cap. No fingers on those.

 

Thanks that helps a lot! Will be looking at it in the morning

 

Dang, I didn't even notice you had a 2nd gen. I'm 3rd. I still think I'll take your advice, tho. I'm getting more and more stressed about this leaky top.

 

Update!
My cap is installed, and it leaks on the cab rail. Side rails are pretty good, as the cap actually overhangs the side rails, similar to shingles on a roof.

The cab rail is just a nutty design to begin with, and the cap isn't designed to overhang as far as it needs to to act like a roof there.

I'm considering adding a strip of flashing around the entire cap. Considering something like 1/16" EPDM roof material. I'll fasten it high on the inside of the cab and low on the outside. In the pic below, cap=siding and flashing=EPDM.








The theory is that there is so much moving and shaking here that adhesive sealants will never last, and that I have to depend on the structure of the material.

 

Just follow my steps posted earlier. No need to go crazy and come up with a crazy solution.

 

I'll give it another read, for sure.

 

What type of sealant is best for the bedrail paint and plastic rail? I think something non-hardening would be better on a vehicle due to the natural rattling and movement in that area. I'm leaning toward Geocel Proflex RV sealant, which is stronger and more durable than silicone sealant, but I don't know how the paint on the bedrail would react to it. Here's a link: https://www.geocelusa.com/product/pro-flex-rv-flexible-sealant/