Hidden Rust Inside Frame Tube

[RobotMartian]

I was replacing the fuel pump and decided to go ahead and drop the fuel tank and do some general cleanup/frame rust/epoxy touch ups. While I was sanding in the tank area, I noticed some slight epoxy bubbling towards the back. The epoxy in that area was still solid and in place, just slightly bubbled. I decided to send a snake cam in through the hole in the frame (picture attached) nearest the issue. A circular portion of the inside is rusting enough to cause slight bubbling through the otherside (tank side). The camera's photos are attached. Even lifting the tub off would not give me access to the frame interior. I'm wondering if anyone has any ideas short of cutting a hole in the frame to access the interior. The only thing that I can think of is to flood the cavity with something like undercoat or Rustoleum.

[dn010]

Coatings won't do anything for you- they only have the best chance of working with "treated" rust and who knows what else is under the epoxy. Without cutting, you'd have to find a way to peal the epoxy off, scrape off any scales, treat the rust and cover it with something like KBS rustseal which I prefer 1000X over POR-15. Just smearing this stuff over rust as it is like you have in the picture will only make you feel better about and make you think it's fixed, but the rust will still be there, spreading.

[David T]

Spreading "stuff" over the rust will slow down any spread by preventing air (Oxygen) from getting to the metal. Not a permanent solution by any means but better than nothing. If the car is kept garaged and not driven in the rain or snow, what I saw in the pictures is nothing to worry about.

[DMC-Ron]

You could blast some Corrosion-X in there. It's available in a spray can option. Use the flexible nozzle and coat the surfaces as best you can. It will drip out of the car for several days after treatment. As David says, it won't undo the rust, but it will react with it and encapsulate it.
If you inhibit oxygen access the cancer is stopped. Corrosion-X is used extensively in the aircraft industry to stop corrosion. Here is the link for the spray can version:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Ron

[Drive Stainless]

You could blast some Corrosion-X in there. It's available in a spray can option. Use the flexible nozzle and coat the surfaces as best you can. It will drip out of the car for several days after treatment. As David says, it won't undo the rust, but it will react with it and encapsulate it.
If you inhibit oxygen access the cancer is stopped. Corrosion-X is used extensively in the aircraft industry to stop corrosion. Here is the link for the spray can version:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Ron

Ron, have you used Fluidfilm? How does this stuff compare?

[RobotMartian]

Thank you for the advice, guys. It is garage kept, so that is a plus. I understand that products like POR-15 and Rust-Oleum essentially create a hard film/coat to prevent oxygen access. Does Corrosion-X work by coating the metal in an oil layer, similar to oiling a firearm to prevent rust? If I'm reading correctly, it also works by a chemical reaction with the rust to further encapsulate it. That is pretty rad. Would that make it a POR-15/Oil protection hybrid of sorts?

[dn010]

Thank you for the advice, guys. It is garage kept, so that is a plus. I understand that products like POR-15 and Rust-Oleum essentially create a hard film/coat to prevent oxygen access. Does Corrosion-X work by coating the metal in an oil layer, similar to oiling a firearm to prevent rust? If I'm reading correctly, it also works by a chemical reaction with the rust to further encapsulate it. That is pretty rad. Would that make it a POR-15/Oil protection hybrid of sorts?

POR-15 or KBS both do harden to a solid coating preventing any moisture or air from attacking the [treated] metal further, problem is you can't just smear it on scaly, dirty metal, it will only end up pealing off like the epoxy does - and then as I stated, it won't do anything without the metal being 'treated'. Corrosion X looks like your best bet however I don't have any experience with it so I cannot comment on it.

[David T]

Products like Corrosion X do try to convert the surface into a non-oxidizing layer to stop any further corrosion and also seal it from the atmosphere to prevent the Oxygen from getting to the corrosion. They also are intended to "creep" and cover more than just what you sprayed in an effort to get into all the nooks and cranies. These products are not a permanent solution. They can be washed out by water so they must be reapplied regularly. "Back in the day" there was a product called Zeibart (I think that was the name) which was a waxy solution the car dealers offered to do on new cars to prevent rust. They drilled holes all over the car and sprayed in into the doors, rocker panels, chassis and such. They offered a warranty against rust. It didn't work well. Conventional undercoating eventually gets hard and brittle and cracks like the epoxy does and water gets between it and the metal. The best solutions so far are making the frame out of a non-corrosive materiel like S/S or plastic or carbon fiber or zinc coated steel. Zinc coated steel, AKA galvanized steel, is heavy and expensive but seems to be the way to go for most car manufacturers. All of the wheel wells and other small parts are now plastic. They are a twofer. Lighter and corrosion resistant. For an added bonus they are also cheaper. DMC was way ahead of the times, they used a plastic gas tank. Now everyone is using them.

[SpudMurphy]

Get a spray in there - rust killing sprays followed by a wax spray treatment. It will keep the rust in abeyance for a long time yet.... and in the future there may very well be a cheap new frame solution?
Spray wax in there every year - it will be fine.

I'm going to slap really thick grease over mine, spray inside the cavities and that will help it.

I remember cars in the 70's that were wax treated (like the Ziebart option already mentioned) - when it was done well, it worked a treat - when it was done badly ... well go figure.

[DMC-Ron]

Ron, have you used Fluidfilm? How does this stuff compare?

Matt,
Sorry I do not have experience with Fluidfilm.
Ron