Author Topic: Best method to waterproof (and rustproof) vehicle roof rack?  (Read 424 times)


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Best method to waterproof (and rustproof) vehicle roof rack?
« on: January 08, 2022, 02:02:46 PM »
Hey all, I received an extra long roof rack for my 4runner for xmas and want to water proof (and rust proof it) to the best of my ability before installing it.  I live in NY, do not have a garage, and intend to leave it on 24/7/365 so direct sunlight in hot summers and cold winters.  I grabbed two cans of rubberized bed liner to spray the whole thing, and some Krown anti-rust spray to spray inside, but my question is about where the rack pieces slide into each other and where the screws connect the pieces.  I purchased both Black RTV Silicone Instant Gasket and JB Weld Steel Reinforced Epoxy.  Will either of these work for creating a water proof seal where the roof rack pieces connect and where I screw them together or is there something else I should purchase?

Lastly, anything else I'm forgetting?  Oil based rust inhibitor inside, seal all connection points, truck bed spray the whole thing?

Thank you!
« Last Edit: January 08, 2022, 04:02:46 PM by cdgreg »

Paper Chaser

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Re: Best method to waterproof (and rustproof) vehicle roof rack?
« Reply #1 on: January 09, 2022, 09:26:02 AM »
Have a pic? Is there any finish on it now?
Oil based sprays work well for the underside of vehicles, but I'm not sure I'd want it in something on my roof where the oil can leak/drip out over time and get all over the paint and door/window seals.
A lot of powder coating shops can coat things inside and out with a permanent coating. I'd check your area for those and take a pic so they can let you know if it's feasible or not. It might be a couple hundred bucks, but it will be permanent instead of needing periodic replacement like krown.


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Re: Best method to waterproof (and rustproof) vehicle roof rack?
« Reply #2 on: January 10, 2022, 06:39:17 AM »
Maybe a stupid question, but is your rack steel or aluminum?  Does a magnet stick to it?  If its aluminum, rust is not a concern, though corrosion where your screws connect the pieces might be.


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Re: Best method to waterproof (and rustproof) vehicle roof rack?
« Reply #3 on: January 10, 2022, 08:22:55 AM »
Personally, I would do nothing to the roof rack. It will most likely outlive the 4runner rust-wise. I also think that adding coatings and sealants might complicate how it fits together or later remove it if needed for some reason. Not to mention, doing so would probably void any warranties on it.


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Re: Best method to waterproof (and rustproof) vehicle roof rack?
« Reply #4 on: January 10, 2022, 11:10:26 AM »
I agree with everything lthenderson said and the reasons why. If the product is new and of decent quality it is likely designed with a lot (if not all) of the conditions you list in mind. The road salt will probably take the 4runner out before a good quality roof rack fails due to exposure.

If it is not of decent-to-good quality I suppose there are something you might be able to do to increase its longevity. It still seems like your approach is overkill.

The oil inside is not a permanent solution and even without all of the other steps you are suggesting, I doubt you will be taking it apart every again to reapply. All of the other sealing steps ... if they are not 100% watertight today and for the life of the product ... could end up trapping water that would have otherwise drained and hasten failure. I suppose silicone would work, but I would be leary of epoxy over the long term of something that is prone to flexing/repeated impacts/vibration.

If this is an upcycle/second life for the product painting/bed lining could extended the life of the product by replacing a failed coating/barrier.