How to prevent box section chassis rusting from the inside?

[montyjohn]

Hello all,
I’m restoring a chassis (JPR Wildcat) that when new would have looked like the image below.



Mine does not look like that (it’s 20 years old now). I’ve had to replace most of the lower box section which was made form thin ERW that has rusted form the inside.

I want to make sure this doesn’t happen again, so my plan is as follows:

1. Drag wire pipe cleaners through the chassis to remove loose rust, blow with an airline and then spray with waxoyl. This will likely require some holes to be drilled.
2. Paint the outside with full POR15 system (clean, prep, PO15 and top coat).

My question is how to deal with water ingress. My two thoughts are:

1. Seal up everything to try and prevent water getting in. Problem with this approach is water will eventually get in somewhere, and then what, it will just sit there and will eventually find weaknesses in the waxoyl. This leads me to the second approach.
2. Accept water will get in and drill drain holes along the lower side of the lower box section. I can try and flare the holes backwards to reduce the amount of spray that will enter. This approach almost encourages water to enter but allows it to drain and therefore dry (I would probably drill some vent holes at the top also to assist with drying).

Any experience of which approach is best or any tips and tricks anyone wants to share will be very much appreciated.

Thanks in advance.

[helix402]

Don’t use Waxoil, better products are available, such as anything by Bilt Hamber.

[montyjohn]

helix402 said:

Don’t use Waxoil, better products are available, such as anything by Bilt Hamber.

Thanks for the tip.
Reviews for Dynax-S50 look pretty good and will probably be the direction I go.

[Dr Doofenshmirtz]

Waxoyl, which is a Wax based product (duh) is perfect for clean rust free metal. It's a permanent solution for unpainted box sections, and does work.
Dinitrol which is a grease based product is better for metal that has light rusting. It will soak in slightly to the rust and stop air & moisture causing further rust. It's a semi permanent solution but should be reapplied every two or so years on exposed sections.
If the rust has really taken hold, then only ACF-50 (which is oil based) will stop it getting any worse. it needs to be reapplied every year but will definitely stop further rust developing.

There are other variations or manufacturers selling Wax or Grease based products, and they're all much of a muchness (i.e they create a barrier between the metal and air/moisture). ACF-50 is the only one I use on existing rust though...the ingredients they use turn the brown flaky rust into a blackish stuff that helps to seal in the product. It's amazing stuff but not many people seem to know about it.

[arguti]

The fact that ACF 50 is used on carrier based aircraft should give you some idea as to how effective it is!