Undersealing - advice please

[DaveCoupe]

I've done a bit of a search on here and on AOC. I'm still a bit unsure of the best way to tackle it and the products to use.

The situation as it stands, my Mk4 coupe is off the road, as usual in winter. The back is jacked up and all of the rear running gear is off being cleaned or powdercoatred. Basically I have a blank canvas now to go mad. The spare wheel well has been welded up and seam sealed, but this is starting to go a bit crusty now. I will remove the fuel filler neck and lower the fuel tank so I can get to nearly all of the rear section.

Now, do i just clean all the crud off with a degreaser, a wire brush, and a jet wash? Or do I go mad and get the wire wheel on it?

And as for products, I've had a couple of ideas. My first idea was to paint a full covering of stoneguard and then go over this with the Waxoyl/Hammerite paint. Then i thought "would roof weatherproofing paint not do a similar job for half the price?"

Lemme know what you think guys.

Cheers

[8valve-craig]

Ive recently been doing my mk2 astra, As long as you have a clean surface to work with just buy a big pot of hammerite waxoyl and paint it on with a brush.

Wire brush / wheel over any scabs or it will just peel off.

[DaveCoupe]

How thick is the Hammerite Waxoyl paint, won't it chip or flake?

I've heard loads of horror stories of the rubbery stuff rotting from within if it gets hit with stones etc

[8valve-craig]

Its not that thick, its just like a bitumin paint. It certainly wont flake or peel off.

[DaveCoupe]

Ok mate, sound. I might still put a coat of stone guard on and this over the top

[Prey001]

You definately dont want to just put waxoyl on over bare metal - wherever its bare you want to etch prime, prime and paint and then stick whatever wax/stoneguard of your choice over the top.

[8valve-craig]

Ahh... I just brushed hammerite smooth over the bare parts before waxoyl. (pic 1 taken way before grinding was over)

But if i have trouble with it in the next few years will just lift it up and do it again.

[gixerboyuk]

thought mk4 astras would be galvo dipped? Not that thats the answer to the prob, but the more you cut back the worse it will get if not treated properly.
Would have used the wire twist in the angle grinder, then a good rust killer/stopper for the ropy bits left, seam sealer where reqd and then prob a red oxide primer, followed by a L/R chassis paint, topped off with underseal or stone chip (summat you can spray).
Bearing in mind if you've cut back to the seams to clean it's prob already to late an your only delaying the death! lmao (all be it another 10 yrs )

Hammerite is the devils spunk and only good for your garden gates (as advertised if you look)

[8valve-craig]

3yrs would be a bonus