Land Rover Chassis Repair - Rust and Welding

Clean as mentioned above, but then take an old screw driver or ice pick type tool and poke at it, especially in the corners, poke very hard and literally try to stab a hole through the surface, some places you will (If it is rusted badly) then work at those holes and make them as big as possible with your poker. 

You can also take a ball pein hammer and hit the chassis all over, you should hear a good pong pong sound each time, when you hear a dull thud you will have either found an internal support, very internally rusted spot or a spot where there is a lot of mud or gunge inside. Concentrate on this spot until you have established the cause of the thud. If there is sand/mud/gunge inside, drill a large hole, 14mm or so directly beneath the problem area, if there is already a drain hole it is probably blocked.

Once everything is cleaned up, you can carefully asses the damage. You may consider cutting the holes out or cutting out entire sections and replacing them with new good sections. Anything larger than a finger hole or a mass of little holes must be cut out and replaced.

If they are flat sections, cut back until you cut into good steel, obtain new pieces of plain mild steel, treat them as explained on this page and weld them in place.

If your rusty bits include some major piece of chassis like a spring hanger or bumper horn or even a whole cross member, then you must make a few careful profiles on stiff cardboard or sheet steel and take careful measurements, including diagonal measurements to ensure that you fit your new replacement section in the exact same place as the original. It may be a good idea to drill a reasonably large hole in the item such that you can get a small paint brush in to paint it once it is all welded back together.

Treating a Rusty Chassis on a Land Rover

Use a wire brush, either hand operated or on an electric drill, on the surface and try to remove as much rusty material as possible, don’t be worried if you create a hole, attack the surface with a vengeance.

Anything that is vaguely rotten will come off, sometimes if the rust is severe, you may need to use an angle grinder with a grinding disk. Grind the surface lightly. Brown dusty powder is rust and must come off, only when you start making sparks and the surface is shiny can you move on to another area.

Once all rust has been removed you can patch up the holes as needed (See next section)

You must then clean the surface with water and let it dry properly.

If the surface is vaguely rusty or still brownish/blackish in colour you must paint it with a Polycell product called RUSSIST. An alternative is straight phosphoric acid but it is less effective than RUSSIST.

Russist contains phosphoric acid which reacts with the rust (iron oxide) and forms iron sulphate which is dark blue/black in colour and is resistant to further rust. It is for this reason that you must only apply this product to RUSTY metal as it does not bond on clean steel.

You should apply the russist as instructed on the container, then apply your favourite paint as the russist acts as a primer for most paints. Russist can be sprayed on and you can apply spray paint onto russist.

If you used straight phosphoric acid (With gloves !) you must thoroughly wash the item after the it has stood for a good few hours, then let it dry and apply paint.