Yet Another Leaky Topper

I am sure this has been beaten to death over and over again, but I have a new question-

I bought this first gen taco a month ago and it has a drop in bed liner in it. someone before me had cut whole in it to get to the hooks and to attatch clamps for a topper (I assume. there are random holes with nothing on the inside so I have to assume thats what it was for)

I bought a topper to put on it ( an old leer that was designed for these years). I have been beating myself trying to water proof it all up because I want to build out the back for a camping setup, but I have been quite unsuccessful. I replaced the seal on the bottom of the shell with this


and it seemed to work, but I found out that the window seals were leaking. I tried to seal it from the inside with a clear silicone, but the water would just pool behind the silicone and it would still leak. Today, I went all out and lined the contact between the seals and the shell with

$33 3M 5200 (06504) Permanent Bonding and Sealing for Boats and RVs Above and Below the Waterline Waterproof Repair, Black, 10 fl oz Cartridge

3M 5200 Marine sealant, and taped off the windows and coated it all with clear flex seal on the inside.

I am really hoping this works, but I am still getting a couple dribbles of water around the gasket. I am wondering if the seal will be better without the drop in liner? Would I have a better contact with just the raw bed (and I would get a rubber bed mat)? That would make my build a bit easier not having to deal with the ridges in the bed liner. Looking for any thoughts on anything I have said to make it go smoother. Thanks

 

You used 5200 on the cap? Did you read the part about it being permanent? Whatever you bonded with it is now permanently attached

 

yeah I put a bead between the cap and the window gasket on the outside. The topper is so old that they don't sell the gaskets for those windows anymore, and if I were to replace the window assembly, it would cost more than just buying a new topper all together so it honestly isnt a big deal...