Driving your 4WD through salt water; why its a dumb decision

There are plenty of ways you can neglect your 4WD. Ignoring the recommended service schedule, bouncing your way up a hill with wheels going everywhere, not adjusting your Tyre pressures for the terrain or simply giving the engine a hard time. How you treat your 4WD is entirely up to you; it’s yours, and you are the one who has to cough up the money to have it repaired.

However, I am confused as to why people still seem to think there is nothing wrong with Driving their 4WD’s through salt water.

Water crossings are a part of 4WDing, and happen all the time. Providing you take the recommended precautions, water crossings are no drama. However, if you like your 4WD, I’d seriously recommend you stay out of salt water! It’s high up on the list of 12 ways to wear your 4WD out faster.

Fresh water crossings
Stick to freshwater crossings

What’s the big deal with driving through salt water?

Pretty well all of the metal that makes up your 4WD is vulnerable to rust. When it comes from the factory, it is painted and protected (to an extent) from rusting. However, regardless of a 4WD’s age, rust is a serious threat. Driving through salt water in your 4WD is the best way to start a very expensive journey of future rust repairs.

Water gets into everything, and will sit in places you can’t wash out or even see, causing hugely expensive damage as time goes on.

4WD rust repairs
Salt water is the easiest way to make your 4WD rust away

Rust in your 4WD

One of the most expensive repairs you can be doing on a 4WD is trying to fix panels that have rusted away. Rust is referred to as cancer for cars, and it really is a terrible thing. Once rust starts, getting rid of it is a nightmare, and a very costly exercise to do correctly.

I’ve always believed prevention is better than cure. If you look after your 4WD, it has very little chance of rusting, and you will never have to worry about it. However, neglect your vehicle, and there’s a good chance in a few years’ time it will be worth very little!

Rust is a slow process. It doesn’t happen the day after you’ve driven through salt water. It starts slowly, and months go by before you will notice anything. By the time you can see evidence of rust though, it’s usually too late.

GQ Patrol rusted floor
Cutting out rusty floor panels in a GQ Patrol

Where does the rust usually start?

Your body panels are the first thing to start rusting on a 4WD. The panels are not very thick, and have plenty of spots where water can sit and start the rusting process. Gutters, window sills, around the windscreen, wheel arches and the vehicles sills are the most common places for rust to start, and often you won’t see it until the rust has a good hold of your panels.

Rust in your chassis is very common too, but being a much thicker steel the rust takes a lot longer. If you find rust in your chassis, you’ve likely got a much, much bigger problem!

Salt water and insurance

A vehicle that cops a decent amount of salt water through the body is usually a write off. Sometimes this is due to damage to the electrical components, but if your 4WD gets caught at high tide and fills up with salt water, your 4WD insurance company will class it as a write off.

This is a pretty clear indication of how serious salt water damage can be. If you’ve ever seen a 4WD that has done a lot of driving in salty conditions, it’s pretty obvious why they get written off. It is nasty stuff.

Salt water is a recipe for disaster
Insurance companies hate salt water

When do people drive through salt water?

The most common place people drive through salt water is on the beach. Sometimes it’s to cross a river, or because the beach has become too narrow to continue. Other times, it’s just because people choose to drive through salt water.

Sure, a photo of your 4WD driving down the beach with salt spray going everywhere is nice, but it’s going to cost you an arm and a leg in the long run. I’ve seen 4WD’s drive along a beach that’s 50 meters wide, and they head straight down to the water, just to flick it around everywhere. It might be fun, but the bill you will have to pay in the future to repair the rust won’t be.

Salt water crossing
If you like your 4WD, don’t do this!

Can you avoid driving through salt water?

Yes. I’ve never driven any of my 4WD’s through salt water. I’ve come close a few times when things have gone wrong, but I steer well and truly clear of getting salt water on my 4WD.

Most of the time, it comes down to a bit of prior preparation; look at the tides and work out whether you have enough time to drive the section of beach you are on. Make a commitment to your 4WD; you are going to take care of it, and that means you avoid anything that can damage it!

If you have to cross rivers that flow into the ocean, these are usually fresh water, and can be crossed without getting salt water on your vehicle, simply by timing the waves and driving through in the right location.

Swimming in salt water
Enjoying a day on the beach without taking the car swimming

I wash my 4WD when I get home though

I hear people who’ve driven through salt water say ‘but I wash it when I get home; it’s not a problem’. No matter how well you clean your 4WD when you get home, you aren’t going to get all of the salt traces off your 4WD. You might get the majority of it, but you still risk rust down the track. It’s not worth it; avoid driving through salt water and you will have a vehicle that lasts much longer

Isn’t driving on the beach just as bad though?

Those who drive through salt water often argue that Beach Driving does just as much damage to your 4WD as going through salty water. This is not true. Sure, beach sand has salt in it, and just by being close to the beach allows salt mist to blow onto your vehicle, but it’s nowhere near as bad as drenching your 4WD in a salt bath.

You should avoid driving through wet sand that flicks up under your 4WD. If you have to drive on wet sand, do it slowly so it doesn’t flick up everywhere.

Beach driving cleaning
Take the time to wash your car after driving on the beach

What’s the best way to prevent rust on your 4WD?

4WD’s that are used off road should have a few things done to minimize the risk of rust developing. The most important thing to do is to wash your 4WD after each trip. This is especially important after driving on the beach, or through mud (mud actually has a high salt content!).

By wash, I don’t mean a quick drive through the local car wash (although this is better than nothing!). You need to wash all of the panels, as well as the underneath of your vehicle. A good rinse off underneath (making sure you do all of the panels, inside the chassis and anywhere water can sit) is the best way to prevent rust on your 4WD.

Another very popular rust prevention method is to use lanolin, or fish oil underneath your vehicle. I usually spray our 80 series underneath once a year with lanolin, and give it a few days to dry. You can spray everything except for seals, your engine and exhaust pipe. Lanolin is a sheep by product that creates a protective coating. It might smell a bit, but its cheap insurance (and the smell eventually goes away!)

Another alternative that has been around for several years now is known as ERP, or Electronic rust protection. This is a bit of a controversial modification though, and possibly because of a number of cheaper versions that have come out and really achieve nothing. Some people swear by ERP, and say it makes a massive difference. Others though think its like snake skin. From my perspective, my 80 came with an ERP system (no idea what brand) but it still has some rust. I can’t tell you whether its minimized the rust or not; I’ll never know!

If I have to drive through salt water, what should I do?

On the odd occasion, you may have to drive through salt water. Whether you made a bad call and have ended up in a bit of a situation, or you need to cross a section of beach, the best way to drive through salt water is to minimise where the water goes. Don’t drive flat out across the water and splash it over every single part of your 4WD.

Take it slowly, and reduce the amount of water flicked up everywhere, and your 4WD will thank you later! I’ve only driven through salt water once, and it was a complete accident and one that I seriously regretted later on. You can read about it here; Timing the tides and waves; the day I got it wrong.

Drive slowly through salt water
Slow and steady wins the race

Do you drive through salt water?

I was taught from a young age to take care of things that you own, and my Dad was always dead against driving through salty water, having seen the damage it can do to cars. Maybe you disagree with me. Do you ever drive your 4WD through salt water?

See you out there!

Sharing is caring!

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *


  1. Hi Sammy,

    I would say you’ll see some impact of the rust. You need to get the salt out of every nook and cranny, which is almost impossible. I would be using a sprinkler underneath for several hours in different locations, and trying to put the hose down all of the chassis members and everywhere possible. There might be some professional washing services that could be of assistance, done on a hoist with the wheels of etc.

    Unfortunately salt water is nasty, and its very hard to get rid of. It won’t rust over night, but it will do long term damage if not completely removed.

    All the best

  2. Hi there, I know it’s an old thread but I hope someone can still answer my questions please.
    I was forced to retrieve my boat from the beach recently for the first and only time, and I got the underbody of my Subaru Outback almost fully submerged in seawater by the incoming waves. When I came home I washed the underbody with plenty of water and went through a the car washing (with underbody wash) the next day. Is one time enough to cause the car to fully over coming years rust or should I be ok if this doesn’t happen again?? Thanks all! Sammy

  3. I have no idea when it was installed. I still doubt it works very effectively. Prevention is better than cure; I’d rather stay out of salt water, apply lanolin once a year and clean it after every beach run. One day I will look at what brand the ERP is; I’ll let you know!

  4. Ashley Earl says:

    Given the 80 was around before ERP there’s a good chance the rust was there before the ERP was installed. I found with our Safari the existing rust never got any worse after I installed the Couplertec unit on it and we were not overly careful to wash it after beach runs. I’ve just put the same unit off the Safari on our Patrol so will be interesting to see what happens with it now. I think there may be quality issues with some of the cheaper units and also installation pays a big part in how they work, poor installation of couplers + earth etc. can mean they will function poorly or not at all.

  5. Good to hear mate. Its a shame that its so hard to prove, with rust being so slow! I know mine uses power, and you can actually hear it if you have your head in the bonnet and its really quiet. I think a lot of cheap companies have ripped off the top end ERP products and given the whole lot a bad name

  6. Marek Knappe says:

    My one has it as well, and has some small rust places as well, but not much – i believe that it might be it. Before i bought my one i looked a lot of vehicles, and this has the most rust free body – so maybe it’s doing the job.

  7. Hey Ash.

    I forgot to add it; I’ll fix it now. My 80 series came with ERP. It still has some rust. Whether it has reduced the rust, or it doesn’t work I’ll never know. Some people swear by it, but just as many swear at it!

  8. Ashley Earl says:

    I would have thought electronic capacitive rust protection would be far better than lanolin or fish oil. If you can’t get to places to wash them you can’t get to them to spray with Lanolin etc. Capacitive protection works on the complete vehicle not just where you can get to. The systems work to turn the vehicle in to a cathode preventing the possibility of ionization (metal corrosion).

  9. Marek Knappe says:

    What about electronic rust prevention system? nothing mentioned about that.