I hope everyone reading or replying to this thread is aware of where this rust is coming
through from?
For instance, the typical rust in the photo above from Jaylee:
http://i1088.photobucket.com/albums/i33 ... 1_2139.jpg cannot be felt by reaching under the wheel arch with your fingers, as it's located - hidden - in
between two metal body panels. One panel is the painted outer body wing you are actually looking at, and the other is the panel
under the arch which surrounds the wheel - ie: the muddy panel you see beyond and above the wheel! To gain access to where this rust is actually taking place, you need to remove the plastic storage pockets fitted inside your vehicle over each wheel arch, and have a look down there where you'll see where the two panels join. And where the rust forms.
The two panels involved are joined along their seam by, I presume, spot-welding. The problem here is that the spot welds are - what? - a couple of inches apart from each other? This means that the 'seam' is not completely sealed but will have very small gaps between them (think of two sheets of paper laid on top of each other and stapled along one edge every couple of inches. In between these staples the paper will not be joined or sealed). And, because the two sheets are fitted very
tightly together, this will actually
draw water in between them by capillary action.
If you reach just under the wheel arch with your fingers and feel the sharpish edge behind, you are fingering where two sheets of metal touch and join. This edge will be sprayed with water whenever you drive in the wet and water will be drawn in by capillary-action between the two layers where it will settle as there is next to no air flow to dry them. The water will sit there hidden for hours afterwards doing what it does best - causing rust. It
might also be the case that moisture originating from
within the Bongo (eg, from your sleeping, breathing bodies!) finds its way in between these panels where it condenses against the colder outside panels, but that's just a guess at a possibility on my part.
So, if you simply sand away rust bubbles as they appear and respray it, it simply ain't gonna work. You are painting over tiny rust holes in the bodywork - where water and rust will come back through in no time. If you simply Waxoyl under your wheel arches, it simply ain't gonna work as you are
not coating and protecting where the rust will
begin. (Having said that, I reckon there might be some mileage in coating the 'edge' of the join with Waxoyl or similar in the hope it'll seal off this edge to the elements. Mind you, that's a very thin edge you are trying to coat...)
What's the solution? I think you need to seal that seam from the inside. How do you fill such a tight seam? It needs to be bone dry, ideally warm, and the 'sealant' used needs to be very 'watery' so that it, too, will be drawn in by capillary action. Since I like Waxoyl, this is what I use for these kinds of jobs. However, where it comes to such
tight seams, I thin the mix WAY beyond what the manufacturers recommend. I really make it very slooshy indeed (and I use petrol as it's cheap and 'flashes off' quickly - but bear in mind how flammable that is, so I don't recommend it...
) and fire
down through the removed oddments tray apertures above the wheel arches. And I mean really blast that area and saturate it thoroughly. And then again. And again. It's also worth removing the rear light clusters and gently prise out the rubber grommet on the wiring loom. The gap there will now allow a probe to point through. Blast away, dudes!
With luck, a bead of Waxoyl will appear along the panel seams on the outside, in which case you
know you've done the job. However, it might not show, so don't worry! There's no harm in blasting a
neat coat of Waxoyl down there a couple of days later either, just to give the seam in there a darn good coating.
Ok, this will make your car STINK. For at least a couple of weeks. I don't care if you 'like' the smell of Waxoyl, it will drive you barmy to have to live in it, so please don't do this job before a trip!
Bottom line, if an undersealing/Waxoyling/Dinitrolling/ DOESN'T include coating INSIDE these panels, then the weakest rust point on the Bongo will simply
not have been protected in my opinion.
) I had the rims coated to stop it progressing. 2003 bongo, yes in white........ One thing about the white vans is you do notice any rust spots very early on 
Also showing signs or rust at the bottom of the tailgate and behind the rear bumper at the spare wheel release hole.
