That horrible four-letter word - RUST! Chapter One

Once upon a time - or to be precise, in April 2007 - I removed the seats and carpets from my 93 XJ to check and repair or re-seal the places in the floorpan where rust was beginning to show. I posted the detailed story on the forum here.

Well, six years have passed. Like its owner, my Jeep is showing increasing signs of age and the miles under the wheels! I had to replace the rear leaf springs recently (which was another story). But I happened to notice some signs of rust in the floorpan just beside the forward spring-mounting (under the rear passenger seat). So I took up all the floor-coverings again to check it out.

Not a pretty sight. Despite the previous precautions and treatment, as Neil Young says - "Rust Never Sleeps".

Fortunately it isn't as bad as I feared. But this is a cautionary tale to warn other owners to check under their carpets - even if you don't live in places where they salt the roads in winter. Just running in the rain or on wet roads is likely to feed the rust-worm.

My Jeep reveals the two fundamental problems - both of which Jeep should have sorted at the manufacturing stage. This is a warning about the first one:

1. Spot-welded seams let in water. It creeps upwards (capillary action). The most vulnerable and worst place is the seam where the rear floorpan joins the inner wheel arch panel on each side of the load-space. But it is a potential problem all around the edge of the floorpan where it is joined to the side-panels of the unibody. What makes it worse is that in the factory they plastered sealant generously along all those seams..... but on the inside. So if you lift the carpets, it all looks fine. Don't believe it. Under that sealant, the rustworm is at work. Why? Because the foolish factory spot welded the seams and did not seal the outer edges. So water and spray seeps upwards in the seam and spreads along the joins under the sealant. Ask me how I know....

So my advice to anyone whose Jeep is a few years old, is - hack and scrape away that seam-sealant and take a look at the joins underneath. If they are clean, you're lucky. If you see rust, deal with it before the floorpan parts company with the wheel arches.


On my XJ, I found holes in the floorpan of the loadspace at the rear of both wheel arches, just by the fuel-filler on the left side, and in the same area on the right. I found rust creeping all along those seams around the wheelarches, and a rusty hole in the right rear floorpan in the corner of that section under the rear seat where the jack is clipped (this was what I had spotted when looking at the leaf-spring mounting).


The treatment? Welding is an option, but I don't have the equipment. As the holes were small and the rust along the seams not severe, I took a grinding wheel to the rust and cleaned/cut it away, then treated with rust remover and rust converter. Then I folded in the spot-welded seams where the floorpan and inner wheel arch join, and riveted them to the loadspace floor. Finally I patched and filled the holes with mesh and JB Weld. I'm just about to do the priming and painting.


to be continued.....

Re: That horrible four-letter word - RUST! Chapter Two

The dire warnings continue...

As I had taken out the seats and carpets from my Jeep I thought it sensible to look more thoroughly at the rest of the floorpan - especially as I had noticed signs of water-stains and possible dampness in the carpet of the front passenger footwell, despite my earlier installation of extra underlay (rubber mesh and aluminium foil) to keep that absorbent soundproofing diaper-stuff off the metal floor.

This leads to the second lesson, or warning:

2. Those blanking-plugs in the floorpan let in water. Scattered around the floor are circular coin-sized plugs which seal or blank off holes (why were they there - to let the paint drain when the body was dipped in the paint tank?). Anyhow, the factory plugged them with circular metal discs which have spring-clips to hold them into the holes. And guess what - those litle clips, and the edges of the holes, which are exposed to the elements under the body, rust! Worse than that, the factory once again slapped seam-sealant around and over those discs on the interior side. The sealant doesn't work, especially if it wasn't applied carefully. But once again, a quick look suggests all is well. The fact that water and rust is coming up through the holes and creeping under the sealant isn't obvious. Strip it all off and take a look. You'll probably have to replace the disc-shaped plugs too (rubber blanking grommets are one option...) or weld plates over them.

The main offender in my vehicle was the 3" diameter disc plugging the hole in the passenger footwell. I now think this - not an aircon condensation drip - was the original source of the rust I first found there many years ago (and had a patch cut and welded). On the surface it all looked OK - the sealant had been liberally applied at the factory. But when I scraped it off, it was obvious that water had seeped in through the hole, and sat in the channels which run along the floorpan. Carpet underlay permanently wet, and rust beginning to develop.

The solution is obvious. Block or seal off the holes more effectively - and seal them with sealant and/or rustproofing from the outside (underneath) , not just on the interior side. That's another task for me over the next few days.

I took quite a few photos - so may be able to upload some if anyone wants to see them...

Re: RUST! Chapter Three, the wheelarch flares

One task seems to lead to another....

While sorting out the rusty floorpan-edges by the rear wheel arches in my 93 XJ, I thought it would be sensible to clean and re-rustproof the whole of the rear wheel arches. This meant taking off the flares.

Yup, same thing happened to me as everyone else. The nuts holding the inner liners of the flares were all seized and rusted solid. Every single one snapped off.

Of course when I got the plastic flares and the liners off, there was all sorts of crud inside them (20 years of desert sand and river mud!). The metal of the body panels was still healthy. But the stupid metal bracing strips, or mounting strips, which sit inside the flares and anchor the bolts which then go through to hold the liners in place, were rotten with rust.

So.... I pass on as a tip for others the solution I came up with, as I wanted to keep and re-attach the original flares after I had done cleaning and rustproofing.

1) cut out new mounting strips to the same shapes as the original metal ones (each side needs 3 pieces) from flat strips of plastic, not metal. I used some leftover pieces of rainwater gutter;

2) drill 8mm holes in these new plastic strips for the bolts, corresponding to the positions of the holes in the wheelarch body panel;

3) get 8mm (M8) NYLON bolts, 25mm long, with nylon nuts and large plastic/nylon washers (we call them "penny-washers"). Each flare needs seven;

4) put the nylon bolts into the new mounting strips, using epoxy or JB Weld or similar to fix each bolt-head in place and stop it rotating;

5) Before re-fitting the flares, run a bead of sealant around the rim of each wheelarch, since there is a seam where the two panels (body and inner wheelarch) join.... and we know how water and rust love to explore seams!

5) put the new mounting strips, with nylon bolts, into each flare, then offer them up to the body panel, locate the liner on the inner side, and re-fix with nylon washers and nylon nuts.

Job done. No risk of rusted or seized nuts and bolts inside the wheelarches in future.

I still wonder why the factory used metal strips and bolts/nuts to fix the flares into position. Nylon/plastic fixings are tough enough, and they don't rust!

this does look like a great idea for those flares, can you get some pics posted, i'd like to get a good look at how you did it. i know mine are all rusted to crap and need to come off.

I just went through the same thing, I spend 60 hours welding on my 96, in the driveway, in the middle of winter.

Some of the worst spots were right over the rear spring mounts, I got the front of the rear leaf mount floor sheet metal patched up well and reinforced with some thicker metal. I really haven't figured out how I'm going to do the rear spring mounts without doing more damage than good?

I used a coarse wire wheel on an angle grinder and stripped the bottom and top, welded and then painted with flat Hammerite paint (expensive but it lasts and it dries fast). Then brushed on a quality mastic undercoating. Rustolium, rusty metal primer, also lasts well but dries slower.

One technique I've used in the past with good results, is to strip off the old paint and rust. It doesn't have to be completely stripped down to metal, but until you get to a good solid surface and then smear it up with paint, slap a piece of sheet metal on there and rivet it. The paint eventually dries and acts like glue. Go underneath, then lightly hammer the edges of your hole up until it is flush. It lasted around four years, until I had to redo it. I've tried the same thing with resin, but resin doesn't flex well and tends to crack, then sucks up water. One of these days I'm going to get a hold of a good automotive mastic and give that a try.

heshhash said:

this does look like a great idea for those flares, can you get some pics posted, i'd like to get a good look at how you did it. i know mine are all rusted to crap and need to come off.

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Oh dear.... I wish you hadn't asked!

I started out all enthusiastic and took pics of the initial stages of my work in fixing the rusted interior edges of the cargo area where they meet the inner wheel arches, and checking the floorpan. Those pics are on Photobucket here (I hope the link works!).

The bad news is that when I got to the point of removing and re-fitting the flares, I was so focused on figuring out how to solve the problem of how to replace the seized screws and rusted mounting strips - plus it was raining most of the time while I was doing the work - that I just forgot all about taking photos.

Sourcing the nylon bolts and nuts was easy, but it took me a few days to figure out what to use for the mounting strips (I had thought of using that perforated aluminium strip that comes in useful for radio-mounting brackets and exhaust hangers - but plastic guttering was a much better option and easy to cut to shape with a hacksaw).

So I'm sorry I didn't take pics as I worked my way through this.... and now that the flares are securely back in place I really don't feel too keen on taking them all apart to take pics "after the event"!

But don't be discouraged. It really isn't a complicated task. Once you remove (=break off) the original fixings and take the flares and liners off, it's easy to see what is needed and what shape the new mounting-strips need to be. Just follow the steps described in my earlier post.

The only point that occurs to me is that if the sheet-metal of the body panel edges (inside the flares) has started to rust, then the problem becomes harder to fix. There are seven holes around each arch, through which the bolts go to hold the flare and liner in place. If the holes are rusted out and the edge of the wheelarch sheel metal is like lace, then re-attaching the flares becomes a bigger problem. I was lucky: my Jeep body-panels were sound. But in fact this is all the more reason to take the flares off and check on a regular basis (having nut-and-bolt fixings which don't seize solid with rust makes that a lot easier!).

Good luck. Apologies again for lack of pics. If you need any specific advice, feel free to ask!

8Mud said:

.....I used a coarse wire wheel on an angle grinder and stripped the bottom and top, welded and then painted with flat Hammerite paint (expensive but it lasts and it dries fast). Then brushed on a quality mastic undercoating. Rustolium, rusty metal primer, also lasts well but dries slower.

....resin doesn't flex well and tends to crack, then sucks up water. One of these days I'm going to get a hold of a good automotive mastic and give that a try.

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Just a couple of comments on these techniques.

• For some rust a stripping/grinding wheel is better than a coarse wire wheel;
• Hammerite is good stuff (though in my view not as good as POR-15, which bonds better to cleaned-rusty surfaces). Also Hammerite isn't compatible with other types of paint, so choose carefully as it can't be overpainted;
• Rustoleum is OK. In fact once the metal is clean and sound, it's wise to use a primer - preferably an etch primer or a zinc-rich primer - before any other paint-coating;
• Resin filler should never be used in those parts of a chassis or unibody subject to serious stress or load. It's fine for body panels and cosmetics, but is unsafe (and will crack) under stress;
• As a general rule I tend to shy away from "mastic" undercoating. Unless the surface is flawless and coverage absolutely complete including all edges and joins, the demon rust (or rather water and air) can get underneath the mastic and rot the metal unseen. Better, in my view, to use a thinner rustproofing spray like Dinitrol or Waxoyl which creeps along joins and across surfaces. Some people just use a thin spray of used engine oil before every winter! Needs to be checked and renewed every so often, but at least any rust should become visible and can be treated. It's the hidden rust that usually ruins vehicles.