STOP THE ROT!!!

[Pete-M]

Serious question for all you bobble hatted rust fetishists. Underbody rot stopping techniques. Other than the usual "wear a rubber".

 

I don't often bother with all this malarky, but after talking to a few spannermen this afternoon the techniques used vary somewhat.

 

One says "just wire brush it and bladder it with Shultz. It'll last a good few years.

One says "Flap wheel all the rust off, then underseal it with the thickest stuff you can find"

Another started waffling on about getting the metal back to shiny, then painting some mad chemical stuff on, then doing something else, then bladdering it with Shultz or similar. Then painting it..

 

Who's done what and did it work? How long did it take? Any tekkers?

[Split_Pin]

I've found grinding the rust back to good metal, chemical stuff, then rust-killing paint such as Hammerite is pretty effective at slowing corrosion to a snails pace. It worked on my Vectra for 3 years, although I had to keep an eye on it. I dont think it would last forever though.

 

IMHO theres only one way to put advancing corrosion to bed though and thats to cut it out and replace.

[Albert Ross]

If it's structural metalwork, for instance inner and outer sills on a Sierra, I cut out the rot completely, and remake or replace the panel and weld it in accordance with VOSA regs or original manufacturing methods. I paint the insides with stuff like Hammerite as much as I can before putting the last pieces on the outside, and leave a fill and drain hole for Waxoyl*. Then give the outside a damn good degrease, prep, Schutz and prime/topcoat/lacquer. Then monitor weekly for the first 6 months in case of bleedthrough, also a pre-winter re-application of the gooey stuff helps.

 

 

 

 

 

 

*Other wax type Rust Prevention methods are available.

[Pete-M]

This is nowhere near "cut it out" stages. Just a bit of surface grubbiness. Metal itself is solid, but not well protected.

[Split_Pin]

I'd try grinding it right back and applying the stuff your mates say.

 

I had the garage do this to the whole underside of my motor last summer in addition to some structural surgery and the areas that were rusty show no signs of coming back when I checked last week.

[drum]

I've been experimenting with phosphoric acid with mixed results. Acid bath for small parts works well but brushing on the chassis is not so good. Red oxide and stone chip for me.

[Des]

A wire brushing, a coat of Vactan and a blast of the scutz gun will give you the most reward for the least effort, the law of diminishing returns is strong here, I did the whole over the top grinding, sanding, scraping brushing thing last summer and although at the time I thought it worthwhile I now realise I was obsessed and mentally unbalanced to put myself through such suffering.

[Lankytim]

Back in the day a good going over with used engine oil was the approved way of stopping rust.

[skattrd]

What about shot blasting the area with something? Soda?

I've got a motor that has surface rust underneath at present and it's something I'll be considering later this year.

[HillmanImp]

Once i have taken off the surface rust i always use a couple of coats of Hydrate 80 and then a layer of paint. Seems to work like a boss, yo.

[Vin]

I remove surface rust with a cup brush in the grinder and/or a wire brush in the drill. I then tend to treat the area with a rust eater, it depends whats in the garage, at the moment the stuff I have is some american made acid based stuff from Frosts.

 

I then paint the area with 'No.1 rust beater'. Then I'll paint over that with body colour and then stonechip it or underseal it.

[jonny69]

Just so we've got this clear...

 

Schultz:

 

 

Schutz:

 

 

I too have had mixed results with acid treatments. Specifically it turns the surface black and leaves a residue that I've found interferes with the paint I've put on top. It actually said on my tin that after treatment the surface should be rubbed back before painting, which seemed pointless when you could just rub it back to fresh metal and skip the acid stage. I've also had trouble with paint sticking to and reacting with some of those zinc primers, so I tend to avoid them. Plus, where I did use it, I've not noticed it made any difference.

 

If it's not actually perforating the metal, I just take the rust off with the knot wheel on the grinder and repaint it. If it's somewhere where it's going to get chipped or knocked then on my Anglia I used schutz under the paint, which also has the added benefit of masking where your bodywork might not be up to scratch. I really ought to get around to undersealing the car too, with the sticky bitumen underseal stuff.

[Bobthebeard]

After the learning curve that was the sill repairs on my 944, I was concerned about the best way to slow down the rust on the newly welded repairs. Having lots of off cuts of new bare steel repair panels left over I tried an experiment.

Applied several different rust proofing methods on the off cuts and just left them in the garden in the rain to see what happened.

Five months later some interesting* results.

Bare steel..... Rusty as fook

Bare steel with zinc primer..... Rust showing through

Bare steel with Waxoyl.... Slight streaky rust showing through. Was brushed on, rusting due to brush method leaving low spots?

Bare steel with Waxoyl sprayed on.... Tiny rust spots. Very tiny.

Bare steel with brush on seam sealer then brushed on Waxoyl.... No visible rust at all

Bare steel primed, painted with rattle can body colour.... Moderate rusting

 

I used seam sealer brushed on followed by a hefty sprayed on coat of black Waxoyl on the welded bits. Plus drilled holes and sprayed Waxoyl into the inside of the sills.

Guess I need to get out more!

[jonny69]

Which reminds me: I need to Waxoyl my sills.

[Pillock]

I've always used Ku-rust but that's only because I've had the same bottle for years, no idea if it's any better or worse than any other stuff.

Turns the rust (and surrounding paint) dark blue and I've had a few issues painting over it but it does stop the rust quite well.

[Guest]

I sprayed the underside of my Chrysler with a white/grey stone chip first. That way I made sure that when I sprayed the Shultz on, the underside got a complete coating. I usually then do the underside again a few months later when the first coat has dried. Two coats of Shultz and the one of stonechip should see you through a good 5 years of use.

 

Of course, the best way of protecting the underside is to blow-on a couple of litres of both Stone Chip and then Shultz from brand new.....

[406V6]

I have a steel radiator in the bathroom (so hot steamy and damp at times) that had gone rusty on the surface in a few places. I rubbed it back to reasonably bare metal, then applied Vactan which really did well at killing off the rust and forming a paint-like surface. Then I applied a spirit based radiator paint and haven't been troubled by rust since. Had to re-do it when I used water-based radiator paint 'cos marks started to leech through.

[Guest]

Try having your autobox lose a cable and throw its oily contents all over the underside of the heap. That's pretty sticky so, even when stuff goes FOOM there may be an upside.

[garbaldy]

I would love to know the best way also.

 

i flap wheeled all the rust on a transit then two coats of kurust which turned the metal black as it claims, then finigans rust proofing pink primer aparently has glass or some other crap in it, then two coats of white hamerite paint.

guess what 7 weeks later the white paint is all red rust and looks like its never been touched so much for the claims on the tin.