Undercoating inside doors

[69gladiator]

I’m putting the doors back together in my 82 Cherokee and I’m wondering if coating the surfaces inside the door with a rubberized undercoating is better than a couple of coats of Rustolium. The surfaces are totally rust free.

[sierrablue]

It might be better, although if they're rust free after 40 years I don't know that you need to really do anything crazy to rust proof them now (other than make sure there's some paint there)...

Also probably depends how your seals are (or will be), if your door drains are plugged, and how much it sits outside too. If it's sitting out in the rain a lot more, esp. with potentially plugged drains and/or bad gaskets up top, then I might go with the rubberized stuff.

[tgreese]

I would use a product meant for this purpose. Various brands sell as "cavity wax." I have and use Fluid Film, but the go-to for pros is the 3M offering.

https://www.amazon.com/3M-Self-Healing- ... FHDPF?th=1

[SJTD]

More important than what you use is how you use it. In other words, don't plug the drain holes with it. And don't let them fill up with junk through the years.

[letank]

More important than what you use is how you use it. In other words, don't plug the drain holes with it. And don't let them fill up with junk through the years.

Thru the years some of the drain holes went from hole to being fitted with small mesh contraption over the hole to prevent insect from creating dwellings.

[tgreese]

More important than what you use is how you use it. ...

I agree with this in spirit, but in the rust belt there are additional issues to consider. Products like Fluid Film and 3M will penetrate the seams in the steel from inside and (nominally) seal out salty water. IMO these oily products are better than rubberized coating for this purpose. Drainage is not enough IMO. Rinsing with fresh water regularly will help, but that won't displace salt left behind in the seams.

I'd also make sure the door seals and window gaskets actually keep out the water. I replaced the factory door gaskets of my J20 with this rubber seal and it made a big difference in how much less water went to the sills and floors in a drenching rain. Water draining from the doors and sitting on the sills will rot the bottom of the doors from the outside - BTDT.

https://www.amazon.com/gp/product/B0BC8 ... =UTF8&th=1

[SJTD]

I guess I should say "as important".

Yes, keep the water out too.

[69gladiator]

Question for Tim: Does 3m make a product like Fluid Film? All I could find was the rubberized undercoating. I should have mentioned that Fluid Film was another option. My bad

[69gladiator]

I found the 3m product. Google worked better the second go around.

[tgreese]

I found the 3m product. Google worked better the second go around.

Something different from what I linked above?

[letank]

I'd also make sure the door seals and window gaskets actually keep out the water. I replaced the factory door gaskets of my J20 with this rubber seal and it made a big difference in how much less water went to the sills and floors in a drenching rain. Water draining from the doors and sitting on the sills will rot the bottom of the doors from the outside - BTDT.

https://www.amazon.com/gp/product/B0BC8 ... =UTF8&th=1

thank you for the link, yes this is where my leak is coming from... I made a custom top cover tarp... but even the other day , it started to drip, parked nose down

ApillarPassLeakBrox2.jpg

cabCover3.jpg

[tgreese]

Note that gasket I linked has a larger bulb than the original gasket material. I had to adjust the door latches to get them to close, and they need more of a slam to seal. Not perfect. They seal well though.

I cut the material at two 45s for the sharp corners, and glued the ends together with black weatherstrip cement. Ok so far.

[iharding]

The inner door gasket is nice but to me the more important one is the outside one which is unobtainium. It keeps water from getting into the space where the door hinges enter the pillar. Those big square holes let the water into the pillar where it drains out the bottom onto the carpet. I park my Jeep pointing uphill which allows most of the water to drip off and fall to the bottom of the door opening and run outside as god intended. I cobbled together a hillbilly replica of the outside seal but the area where it transitions from diagonal to vertical on the front of the door is a big molded piece in the original and requires some ingenuity to get glued on in a diagonal to seal against the pillar. I tried to talk a manufacturer into taking it on but there are so few of these rigs and so little money in it...