Belly Pan & Underside Surface Rust

Now that we have a 2 post car lift where I am staying, I have managed to get my van fully up in the air to once again inspect underneath. I am not overly impressed with the standard of past work to the sills but overall I don't think it is too bad underneath. A front outrigger & jacking point, and some small patches to the floor are needed.

From my reading of past threads on here, I have finally worked out why my central belly pan is welded on. Apparently Devon conversions welded the central belly pan to give some rigidity and strength because of the cut roof pillars. I was planning on cutting it off until I discovered this yesterday.

From what I can see, behind the belly pan looks pretty good. However there is surface rust. We used a massive Karcher steam cleaner (on warm water setting) yesterday and it seems to be stripping the stone chip underseal which is flaky anyway and seems to have been sprayed directly over welds and underside panels.

1. Should I leave the central belly pan on? Should I remove it and then attempt to weld it back on?

2. What should I do to treat and preserve the general underside? If it was a high value vehicle and doing it properly I would imagine it would be sand blasted or acid dipped and then welded and painted and then sealed. Should I steam clean, wire brush on drill etc and then rust converter treat, then paint, then stone chip?

3. As someone not really familiar with paints and processes, where I have general rust coming through on the gutters, outer sill, rear arch, what is the way forward after cleaning as much of the rust as possible, use rust converter and then a primer paint? I am not sure what primer and paint would be appropriate to be able to then later colour match a top coat and touch up the areas later.

My knowledge of paint seems to stop at Kurust, Hammerite paint and POR15 paint. Obviously where there is flaking rust I will be taking it back or cutting it out, but I'm talking about general surface rust.

 

Put the central belly pan back on but bolt it back ...there could be some threaded holes for you to use and check covered brake pipes or pipe .

 

Odd that it's welded on. My Devon centre pan is bolted. I think Mr Bodger has been at work...

 

On my Devon the side belly pans were welded but not the central one.

 

Indeed. How are you going to install all the gubbins underneath and paint it if you've already welded the centre pan on?

As above, side pans (if fitted) were welded.

 

The centre pan should be bolted not welded. The outer pans are a known rust trap on Devons so its maybe just as well they are not fitted.


Generally to really fix rust you cannot leave rust under any paint coating, as it just carries on rotting with the coating helping it spread, especially if a panel is perforated by the rust, letting moisture in from behind or from any surface holes in the coating. You can hold back the damage temporarily with filler but unless the metal at the edges of the hole is rust free, the filler falls out in the end.

Its always a good idea to have a kit of sandpaper, kurust and touch up paint so that as small patches of rust appear you can slow them down or stop them by fixing them. Yes the amazing paint job and colour matched paint gets messed up but the job of the paint is really keeping water off the metal..

So you have to remove as much rust by scaping/sanding/blasting as possible then Kurust may work but there are better rust converters that do not seal the rust underneath a layer of converted rust (which Kurust and similar preparations tend to) .
Alsobe aware that if metal is rusting from behind, more holes will appear and the rust restarts as bubbling paint. Sometimes the only cure is to replace sections of metal or even open up structures by cutting to access the rotting panels.

Roof and gutter rust can be bad because of the rain ..

The work you do should convert/remove rust to bare metal with maybe pits in it. You then wash the chemicals off, dry and then prime and paint. Hard work. As the metal you expose starts rusting fairly fast ..

Another added approach is to clean up , paint etc .then spray with messy, unattractive wax or oil preparations. Waxoyl will stick on the outside.... Wax on the surface can stop water going into cracks. It really showed up on my bus where a leaky gearbox axle driveshaft seal caused one side to get constantly sprayed in gearbox oil. The other side was much cleaner but rustier.

 

My Centre belly pan came in the back of the van, when I bought it. The side ones are welded. If you hit the side ones with your fist, can you hear rust flakes rattling around in there?

 

I suppose that they built were originally a good idea
But overtime they cover up corrosion of the chassis parts if you can’t inspect what is going on under there ,
I have never owned a van with them

 

I've had 2 like this. First thing - cut them off, then repair everything, bolt the centre ones on and forget about the side ones. Just my opinion.

When showing me an extremely awkward bit to repair one time, my MOT man suggested that if there was a pan welded on top of it he wouldn't be able to see it to fail it. Draw your own conclusions about why your bus has welded centre panel, but I'd be ready for crusty cross members.

 

Or main chassis members with gert great holes in.

Chop 'em off and be prepared for disappointment...

 

Yours looks a million times better condition than this.

 

Looks like the sides have been cut off to fit it between the chassis rails? It's scrap.

 

My van didnt have any pans at all and ive replaced or had replaced all the outriggers and floor sections and cab floor etc etc. Ive had the side pans bolted on for protection and I think they do a fab job of keeping the crap off the outriggers and floor sections. I also think that bolted on ones that can be dropped every so often for inspection is the key. Predominantly my van is garaged for most of its existence now, plus it rarely comes out in the rain and so it dosent get anywhere near as much crap plastered over the underside as its had in its 50 plus years of history. Ive just re installed a pedal pan that ive had in the garage for years and ive got a set of central belly pans ready to go on whenever i run out of things to do on my van. A set of rear mudflaps have just been fitted too. All in all, i think the more protection you can give the underside the better especially just behind both sets of wheels where little shelves are formed for mud to sit on and rust stuff out but i also like the idea of being able to remove them at a whim just to have a little clean and check.

Ozziedog,,,,,,,,,,Bolted on and removeable pans for the win

 

Don't use POR15.

 

What's with the chunky tyres then?

 

Yes , POR15 and Raptor are for confident people with no rust on their bus. If water gets under POR 15 it acts as a perfect plastic bag holding in the water as it doesnt break into flakes as easily as normal paint.

 

And back to your original enquiry. Getting stuff cleaned off and painted for protection is a winner on clean rust free metal. Primer first quickly followed by top coat of some description will ward off the evil rust termites and protect. But remember to clean only as much as you can paint the same day. A light blast with primer is fab fab fab but if there is nothing over the top of it within an hour or so, you may have completely wasted your time because most available primers will not protect against rust or moisture and without your top coat they may have already started to rust behind the scenes, the longer left the more chance.

Ozziedog,,,,,,,,,,, Cleanliness is next to paintiness

 

Compared with the ease of slopping a bit of Rustoleum on, I can't think why anyone would use POR.

I tried it in the early days and, as you say, it just peeled off.