Water crossings are an everyday part of 4WDing. Whether its a puddle, long mud run or river crossing, if you are out and about in your 4WD you will come across water.
Please, take 5 seconds to consider the risk of driving through it, especially if you don't have a snorkel fitted.
What is a 4WD Snorkel?
Most snorkels on 4WD's are plastic, and run down the outside of the A pillar, and through the inner guard to the engines air intake. They are essentially an extension of the factory air intake which can then suck air from a higher location.
What's the purpose of a snorkel?
Any car requires air as part of the combustion process, and from the factory, it sucks air through an intake close to the engine bay. These days many suck air from inside the inner guard, but in the past they have been located anywhere near the top of the engine bay.
The primary issue with this is that contaminants, including dust but most especially water, can easily get flicked or pushed into the air intake, which then goes through your air filter, and if you aren't very careful, into your engine.
A snorkel dramatically decreases the chances of water getting into your engine, and sucks air that is higher off the ground, which is also cleaner. If you've ever driven on a dusty gravel road in convoy, you'd be very familiar with this; the air around the bonnet and below is often full of dust, and above it is much cleaner.
A teaspoon of water can write your 4WD off
For most vehicles, all you need is a single teaspoon of water to get through the air intake and filter, and your engine will hydraulic lock. If that sounds nasty, it should, because it is! In this situation, your engine will seize and stall, and your forward progress will end. That's not a good thing if you are half way through a deep puddle; by the time you rig up a recovery you are going to be swimming inside your vehicle.
If you are very lucky, and mechanically minded, you can sometimes get the engine to run again. However, especially with modern vehicles, your chances are not fantastic. Hydraulic locked engines often have serious damage done to them, as water won't compress like air, and it forces things to bend or break.
If you've done engine damage, there's a very high chance that your insurance company will write your vehicle off (assuming you have good quality 4WD insurance!). This is without even considering water damage to the interior (and exterior electrics) of your vehicle.
Don't go through water without a snorkel
Most full size 4WD's have a wading depth of around the 600 - 800mm range, without a snorkel. However, if you plough into a water crossing and it splashes everywhere, its possible to get water into your engine bay in only 200 - 300mm of water.
If you absolutely must go through water without a 4WD, take it slowly and don't splash your way in. Excessive momentum can be the difference between making it and drowning your 4WD!
Drowned 4WD's in Perth
Every year, there are more than a handful of 4WD's that get drowned in and around Perth (and no doubt the rest of Australia). Some of these have snorkels and have gone through very deep water, but many of them are inexperienced 4WDer's who don't check the depth of a puddle before driving through. Most importantly, many don't have snorkels!
A good mate of mine a few months ago took his relatively new BT50 out to the Mundaring Powerlines Track after some pretty serious rainfall. He'd done the track several times before, and wasn't new to the 4WD scene. He came to a crossing (which could have been driven around!) and having done it before, was confident he'd have no issues.
However, the crossing was just a little deeper than in the past, and after getting halfway across without a snorkel, his 4WD stalled, and died. It took over 15 minutes to rig up a recovery (do you know how hard it is to attach snatch straps to recovery points in dirty, freezing cold water?!) and in that time water got into the 4WD, almost up to the seat level.
Long story short, the vehicle had to be dragged back to the road, loaded on a tow truck and taken to the dealership, where they wrote it off on first glance. It was a stressful week, where he waited to hear whether his expensive family vehicle would be covered by insurance!
Water is deceptive
If you take one thing from this post, know that water crossings are seriously deceptive. You should always walk them, or at the very least use a stick to check the depth and surface conditions (excluding where there are salt water crocodiles around!).
Don't assume that it will be the same depth as last time, or that because you have muddies, lockers and a lift kit you will make it through. Some of the crossings at Mundaring for example, are deep enough to have 100 Series Land Cruisers running 37 inch tyres and 6 inch lifts floating away (yep, that's another story!).
Above all, if you can avoid driving through it in the first place, do that; its not worth the risk.
Here's a few pics of our 80 series, after I decided to drive a track around Lake Jasper that I hadn't checked the depth of. Even with brand new muddies, twin lockers, plenty of power and a snorkel, I bottomed out half way across, and ended up with some water (thankfully not heaps!) inside the vehicle. I should have known better, but made a foolish mistake and paid for it!
What to do if your engine stalls in water
If you enter a water crossing, and your engine stalls, DO NOT try to start it again. In many cases, trying to restart an engine that has sucked water in will lead to serious damage. Recover the vehicle, and if you are lucky, you may get away with draining fluids and water, replacing the air filter, removing glow plugs or spark plugs and turning it over until all the water is out of the engine. Asides from damaged pride and some time spent on the side of the track, sometimes you can get away with it.
Is your snorkel water tight?
If you have a snorkel, check that it is completely air tight from the air box right through the inner guard to the snorkel. Many have fittings that are just pushed into each other, and will still leak water very easily. A snorkel is a preventative measure; if the water is flowing quickly, or you hit it too quickly, or its too deep, nothing will save you! Treat water crossings with the respect that they deserve, and you won't have an issue.
If this post stops just a single person from writing off their pride and joy, then its done its job. I've seen the pain and frustrations of friends having to replace or rebuild 4WD's that have been damaged by water. Get yourself a snorkel, enter water only after you've thoroughly checked it out and you'll have a blast out there.