Aftermarket roof racks and leaks, root causes?

Hey-o,

Question. I have an RCI roof rack waiting to be installed and want to plan it out and I've been wondering about the root cause of leaky roofs due to rack installs. I haven't really been able to find a picture/diagram of what I'm looking for. What's actually causing the leak? Are the bolt holes/threads in the stock location not actually sealed? Is it more of just a thread into the interior? What's the actual path the water takes to get in?

 

Take a look at this video starting at 4:02 you can see him take off the weather stripping and install silicon before putting in the bolts for the rack

https://youtu.be/31DVeJn9HlM?t=242

 

Use a hersheys kiss amount of silicone on the holes when putting the mounting bolts in. Won’t have any issues

 

That's a good view, a lot of videos I've watched just poke a hole through the tape. So do the holes themselves just lead directly into the cab? I always imagined the holes to be sealed...maybe I have to pull the headliner out to get a better picture of it all...

I'm mostly just curious as to how the holes are built into the roof. Imm use silicone for sure. Would love to understand more though

 

Im not sure what path the water gets in. But ive installed 3 aftermarket rood racks (2 on tacomas and 1 on my GX470) proper use of silicone or rtv is all it takes. Lay down sealent around the bolt holes before placing the rack down on the roof. Get your bolts started. Lay down more sealent between the bolts and the mounting surface. When you tighten everything down, the sealent will spread.

Not that bad of a job.

 

Is there an advantage when using rtv over just plain old sealant?

 

I use RTV b/c i can get Permatex brand in the pressurized can.

 

I am asking because I am going to install a roof rack myself soon and I have a tube of Henry's sealant unused at home. Should I go out and buy rtv silicone or will my sealant be fine?

 

is there a reason no one uses butyl tape instead of silicon? i’ve never been a fan of globs of silicon that always end up all over the place.

in the past i’ve just put butyl tape around the washer/spacer and never had an issue and saves the threads from being covered in glop and never had a water leak