Rust treatment for body seams

[Scouse]

I have the dash stripped out of my Defender for assessment & insulation purposes & have found rust starting to become an issue in the main horizontal joint seam.

I'll wire brush & remove the flaky bits & hopefully it won't require welding but I want to treat the seam so this is stopped in it's tracks. I don't want to strip it down each year to check it's progress.

A general Google search has brought up Dynax S50 as being suitable & a search through AULRO has brought up Penetrol as being usefull too.
S50 is advertised widely in the UK classic car mags & their spiel seems quite good. Penetrol seems more widely available in Australia & it's supposed to 'creep' into the seams too.

My other English cars get a hit with fishoil every few years but this goes into readily accessible areas. I'm reluctant to do this to my Defender as it's not so easy to get at.

Any other suggestions?

131564

[mark2]

I've had similar issues. This is what I did:

wirebrush with angle grinder
rust converter, rinse and dry really well with a heat gun to ensure all moisture out of the seam
spray Penetrol over/into the seams (buy the aerosol can with the plastic straw)
let the Penetrol cure for a few days then brush an epoxy enamel over the seam
Sika 227 seam sealer wiped over the seam with a finger
Painted the 227 in topcoat to match firewall


All the seams still look good 4 years later.
A simpler option might be to wirebrush, Penetrol than apply a coat of lanolin spray.
Whatever you do, I suggest Penetrol should be part of the solution.
Checking and rustproofing Defender firewall and door frames (remove door trims and spray inside box sections) every few years is good insurance.

[Scouse]

I'll try the wire brushing & Penetrol I think. I'm not too sure about the seam sealer at the moment. It'd be good to seal the area off but I might leave it open & remove the dash in a couple of years time again just to monitor the rust. If it looks good then, I'll seal it up.
I'll look around for a decent cavity wax to use as a sealer.

I'll also tackle the seam with the car sitting at around 45deg. Hopefully I won't end up with the engine/gearbox contents on the floor.

[p38arover]

I'd consider also using rust converter but one has to remove the excess. That might be hard inside the seam.

[Scouse]

After some research, rust remover (not convertor) would be best for that spot but most are a gel or a soaker, neither of which are ideal for hidden metal on a car. Penetrol seems to be a good option as it's designed to 'creep' into hidden areas.