Trackside Mechanic – Rust Protection


The underbody of your rig tells a big story. So many vehicles come through our shop for either service or roadworthy and it’s usually not until we lift a vehicle that we see the whole picture. The outside and inside may look perfect but a vehicle that has spent most of its life around the coast will reveal itself underneath.

The rear section of the chassis rail on this Pajero has surface rust all over it. There is nothing bad really at this stage but it shows how it gets in everywhere.



That’s right. Brake lines get coated with surface rust. The exhaust system turns maroon with powder. Nuts and bolts seize. The surface of the chassis starts to bubble. The front diff housing and suspension arms just, well, look old. Even rims get that bit of surface rust through them.

Yep, rust is a terrible thing. It gets in everywhere and can make a new 4WD look old in a matter of years.

Driving through salt water or even just being around the salt air, it seems to eat into everything. Not only the places you can imagine, but also those places where you wonder how water bubbles got up through holes in the chassis to soak everything.

But what kind of world would we be living in if we avoided sand and beach driving? A boring one! Driving around saltwater allows us to access some of the places and scenery in the best in the world.

Is there anything we can do to protect our vehicles though? How can we enjoy this without destroying our pride and joy?


There are a number of things we can do. It’s all about preparation and knowing what you want to achieve with your rig.

Just like setting up your rig with a well thought-out drawer system, preparing the vehicle for a trip down the beach needs planning.

Paint: There is a great product called chassis paint that you can get from most automotive shops. This can either be sprayed or brushed onto the chassis, the differential housing, and any other suspension components you would like to cover.

Spray: Lanolin spray and or fish oil spray can also be used to coat the underneath and it’s great for getting into those tight areas or even spraying into the holes in the chassis. Soaking everything like this is probably the best thing that I could suggest.

Couplertec: Or a similar system will also work really well. The idea behind them is they create an electronic charge on the metal surfaces creating extra electrons so the oxidisation process can’t work. It’s best described as having a table with six chairs. If the chairs are filled then no one else can sit at the table. So if all the extra electrons take up any spare metal, the rust or oxidisation process can’t work.

Post-trip care: After any decent trip away, thoroughly wash the 4WD down and soak the underbody, making sure to get the hose into all of those little holes. The worst thing you can do is to leave the salt sitting on the surface.

A combination of all of these ideas will probably work best, I don’t think I would leave it to just one.

When it comes to rust, remember the “Five ‘P’s” – Proper Preparation Prohibits Poor Performance. This will definitely help keep your investment in much better condition.



This is one of the exhaust sections on the Pajero. The system is badly rusted and looks as though if we tried to undo the bolts they would either be seized or snap off. This is the worst affected area of the vehicle. A stainless exhaust is definitely the way to go when it comes to beach work

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