Off-Roading Know-how – Waterworld

In this part everyone’s favourite subject – wading

Everyone who owns a four-wheel drive vehicle enjoys splashing through water. But before taking to it, always stop firsts, get out and check the depth. This is very important. In other words, look before you leap.

The maximum wading depth for a Series Land Rover, Defender, Discovery or Range Rover Classic is 500mm (about 20 inches), which is the underside of the top of the tyre, to the tope of the rim. Exceeding this depth could be asking for real problems. In the case of a petrol-engined vehicle, water could easily kill the high tension associated with the coil, distributor and plug leads.

A diesel-engined vehicle does not suffer from this problem. However, in either case, should water be splashed into the air intake, then catastrophe will come upon you in a split second.

Water would be sucked up immediately into the top of the engine, via the turbo or inlet manifold, and into the combustion chambers above the pistons.

Whereas air is compressible, water certainly is not, and you don’t need much water to ‘hydraulic’ an engine. In extreme cases, the connecting rods between the crankshaft and the pistons could bend and snap with an alarming force, which could send one or more of them out through the side of the engine block. Result – a totally wrecked engine.


.. and the front. Water which is too deep is a major danger

I briefly touched on preparation for deep water wading earlier in this series, but I would now like to concentrate on certain aspects of wading in all Land Rover models.
Land Rover Series I, II and III vehicles have oil bath air cleaners and are sufficiently high enough within the engine bay to keep them out of water.

Land Rover 90, 110 and 127/130 V8 petrol models have their air cleaners high above the engine – like my own 90. Again, no problem if normal wading depth is not exceeded. Yes, I know the accompanying pictures will make you grin!

But on Land Rover 90/110 and 127/130 four-cylinder petrol and naturally aspirated diesel-engined models the air cleaner (paper element type) intakes are lower. Not too clever, should you exceed normal maximum wading depth, or drive too fast and splash water about under the bonnet. If you’re concerned, consider fitting a high-level external air intake, usually called a ‘snorkel’, on these vehicles.

If you use a Land Rover 90/110/130 diesel, Defender Tdi, or Td5 which has its air intake positioned on the side of the wing just above and behind the wheel arch, you could be asking for problems if crossing water that is too deep. Mark my words. The 200 Tdi models have their air intake on the left wing and 300 Tdis, on the right-hand side.

You don’t need much water to splash up across this side vent to cause water getting in. Imagine that you are crossing a fast-flowing river, maybe a touch too deep. The wall of water coming down into the side of the vehicle could instantly cover the intake and completely spoil an enjoyable day.

The only safe answer in this case is to fit an external high-level air intake. Several pounds spent now before embarking upon an expedition into the unknown where river crossings are envisaged, could save a lot of headaches.

Three times during the last few years I have had the task of dewatering diesel Land Rover 90/110s which have taken in water, each time following flash-floods after exceptionally heavy rains. In each case, thankfully, no harm was done – just a lot of effort in stripping down air cleaners, air intakes and intercooler pipes and turbos. Removing heater plugs to expel water in the combustion chambers, by jacking up a front wheel, with vehicle in gear and rotating that wheel by hand to clear the water out of the cylinders. This is followed carefully by short bursts from the starter motor.
Since you end up with the said vehicle each time in deep water – excuse the pun – you then have to check and change as necessary any oils that may have taken in water.

On each occasion, all that showed after were very wet seat swabs which took days to dry out.

I don’t wish this learning curve upon anyone. You have been warned.

Carburettor Range Rovers don’t have such a problem, as their intakes are high above the V8. Mind you, a simple shield made out of aluminium, fitted to the front of the intake, will save water being thrown in by the fan. Efi models have their intake trumpets facing down below the headlamps. Bad news, so keep out of very deep water. That’s a must.

Discovery V8s are much the same as above. Tdi models route the air intake through a void between the inner and outer wings. If you are into serious stuff, fit an external high intake for peace of mind.

Companies such as Mantec Services who advertise in LRO supply these units for Tdi and V8 Land Rovers, Defenders and Discoverys.

I am told that you can’t install a high level external intake on a V8 Efi-engined vehicle as the balance can’t be right for the engine to breath correctly. But I’m sure that Ian Gough of Mantec can advise you if you think you need one.

A further problem associated with attempting to drive through water that is just far too deep is the risk of getting water mixed with oil in either the axle differentials, swivel housings, gearbox/transfer case and the engine. Most of these major assemblies have breather pipes and valves, which could take in water. Water in any of these oils will destroy bearings and gear sets remarkably quickly.

If you don’t exceed the maximum recommended wading depth, then you should have no problems. Check the depth by wading through first on foot carrying a long stick. As the maximum wading depth is just about the average man’s knee, Wellington boots are not going to be tall enough, so if it’s a washed-out track or pool you are checking, reach over from the bank’s edge.

If there are ruts going down into a stagnant waterhole and ruts out the other side, then expect to find ruts under the water too. Establish the depth of water in these rutted areas as well.

Where a stagnant waterhole is likely to be partly full of mud and silt, a river crossing will have clear water flowing. Again, wade out first if you can and reach out with your wading stick to check depth. There are unlikely to be ruts in the riverbed, but boulders strewn across the bed could present quite a problem. Stare into the surface – Polaroid glasses can help here, allowing you to see through the water’s reflection. It is important that you don’t strike a boulder with a front wheel or, just as bad, straddle a large rock, which could make contact with the underside of the vehicle, causing much damage.

Fast flowing water presents its own problems too, in that pressure exerted by the flow can most certainly push you down river. However, it is unlikely that you would attempt to cross a river in a full-blown, raging torrent as the depth would be totally unknown to you. In the accompanying pictures, you’ll see I took this calculated risk to show that there are ‘real’ dangers present.

If you did have to cross, you would need to steer down diagonally across the river to allow the fast-flowing water to escape along the side of you, turning only at the last minute up your escape route on the opposite bank.

Obviously, you would have to enter the river at a point upstream to drive across safely.

It’s always better to find a section of the river to cross at its widest, as the current is weakest here. The strongest current is always at its narrowest point.

Discovery V8s are much the same as above. Tdi models route the air intake through a void between the inner and outer wings. If you are into serious stuff, fit an external high intake for peace of mind.

Once you’ve checked out the route ahead as best you can, and you’re quite clear where you intend to exit the other side, get back into your vehicle and prepare to cross. Select low ratio, first gear (second, if obviously very muddy, to minimise wheel spin). Need I mention centre diff lock? You should have the message by now! Enter the water at the shallowest and most gradual point and pick your way through your pre-determined route as slowly as you can, and up and out of the other side. Don’t rush the water, or it will get up into the engine bay, which you don’t want.

If the water is standing at full wading depth, your front bumper or steering guard will push a bow wave forward, giving a depression under the engine bay, which will help keep this area free from water. Driving too fast, though, through deep water may not give you a good bow wave as your speed will shatter this wave and you’ll run the risk of drowning the engine. Personally, I prefer to err on the side of safety, and drive slower rather than faster.

Don’t forget to dry off brakes when you reach the far side, by gently ‘left foot’ braking for a while.

It’s often said that you should loosen the fan belt to stop the fan from throwing water over the engine, before crossing deep water. On the older Land Rovers this is easily done, but with newer models you can often find up to three drive belts, none of which are easily adjusted. In any case, it’s usually the crankshaft pulley that spins the water up first.

If you really want to prepare for lots of deep wading, fit an electric fan instead, and switch it off before you cross.

As regards the intakes for fresh air heaters, which appear on either of the sides of the front wings, or on top of them on newer Land Rovers, consider blanking the grilles with gaffer tape. If you end up shifting a lot of water, and the blower unit is switched on, you could get drenched inside!

If you think there is a likelihood of getting stuck in the water, then have a towrope already attached to the front to assist in a quick recovery. There’s nothing worse than trying to attach a rope with a shackle right under deep water. If you do become stuck, either you or your passenger – don’t they come in useful? – can climb out of the window, unhook the loose end of the rope draped around the spare wheel on the bonnet or the roof rack, and throw it to a helping hand on the bank, from where they can hook it to a recovery vehicle.

Another point is to ensure that your engine remains running. If the weight of the water in front becomes too much of a drag for the gear you are in, slip the clutch slightly, rather than risk stalling the engine. The same applies, should the wheels become bogged in the mud under the water’s surface.

If the engine should stall, through water getting on to the high tension, try to re-fire the engine immediately – don’t just sit there, risking water getting into the various housings. Put it into first gear, make sure the handbrake is off, and wind yourself out of the water on the starter. At least then, with the front wheels part of the way up the bank, you can get out and sort the problem.

Usually, with a petrol engined vehicle, a squirt of WD40 over the distributor cap, leads and coil will get things going again. If you decide to take off the distributor cap, think twice about spraying WD40 inside. Firstly, you are more likely to coat the contacts inside which will break down the high tension and, secondly, you will have one almighty bang inside the cap as the trapped vapour is ignited by the high tension. It’s better to wipe out any moisture with a soft, dry cloth, should droplets of water be inside.

As with hill climbing, never underestimate problems associated with water – especially when it is deep.

If you’re crossing a water area that is obviously full of debris, I suggest you hang a piece of sacking across the front of the radiator to stop rubbish getting into the radiator core.

If you are in any way concerned about the amount of water you’ve driven through in a day, then check all oils later for colour. If they look white, grey or creamy, change them straight away. Finally, don’t forget to remove the wading plug(s) that you fitted before driving.

Some automatic Range Rover Efis do not have a threaded hole for the wading plug. All they have is an unsealed slotted hole at the very bottom of the bellhousing. I’ve got to admit, it’s an odd one, this. Perhaps Land Rover has a part number for chewing gum to temporarily fill these open slots.

Checking the Land Rover over after off-roading

So far I have not mentioned the ‘new’ Range Rover. This has been on purpose, as it’s going to be the subject of a future chapter which I will cover on Solihull’s newest vehicles.

The maxim, ‘drive slowly as possible…. and as fast as necessary’, is well worth bearing in mind. This gives you built-in reliability, comfort and, above all, safety – which is of paramount importance.

In a nutshell, don’t try to drive the impossible, or you could sustain damage to the vehicle and suffer either embarrassment, or a real headache in having to be recovered, possibly miles from anywhere.

Having made full use of the vehicle’s capabilities, it’s important to check the vehicle over to ensure continued reliability – and safety on the road.

At the first opportunity, thoroughly power wash under and around the vehicle to remove all traces of mud, which, if left, could set like concrete! In particular, pay special attention to the radiator core. Even muddy water running through the radiator, whilst wading, can cause enormous problems when silt or leaves left behind bake hard, reducing the airflow, which causes overheating.

Pay particular attention also to brakes, by aiming a jet of water around the discs to clean any mud or grit out. The rims of wheels, both on the inside and outside, have a tendency to trap mud, playing havoc with the wheel balance if left uncleaned.

If a power washer isn’t immediately available, clean the mud off the wheel rims at least by scraping it out with a stick, and wipe clean the lights, windows and number plates front and rear.

When power washing the engine, be careful not to direct water towards the air cleaner intake. And on no account leave the vehicle’s engine running while cleaning the vehicle, for fear of water from the power washer finding its way into the air intake with a risk of destroying the engine. You have been warned – again!

Have a good look under the vehicle to make sure everything is in order. Also check fluid levels under the bonnet, including the engine, radiator coolant, brake, clutch and power steering reservoirs.

Check condition of all tyres and re-inflate to normal road pressures, should air have been let out during the day for driving soft ground.

It goes without saying that I highly recommend going to an approved off-road training centre for hands-on experience under the watchful eye of an instructor.

Have fun and get the most out of your vehicle.

Do’s and Don’t’s of Off-Roading

Do read carefully the owners’ vehicle manual.

Do prepare the vehicle in all respects before going off road.

Do prepare yourself and your passengers for the journey ahead.

Do prepare the route ahead to make sure it is actually legal to drive.

Do take an off-road driving course which includes classroom sessions at a recognised off-road training centre rather than find out ‘how to do it’ the hard way.

Do always take at least one other vehicle with you, but try to avoid a convoy.

Do stick to LARA’s code for vehicular use in the countryside.

Do always survey on foot first. You could be very glad you did!

Don’t wrap your thumbs round the steering wheel. The steering wheel may kick back – and leave you with a broken thumb.

Don’t ride the clutch pedal. Keep your left foot well clear at all times when travelling off-road.

Don’t use the footbrake too much. Learn to be in the right gear at all times, controlling the speed on the throttle.

Don’t use the handbrake whilst the vehicle is moving, except carefully in an emergency.

Don’t rely on the handbrake to hold the vehicle if the handbrake brake linings have been subjected to mud and water.

Don’t overload the vehicle, especially the roof rack if fitted, as you will raise the centre of gravity.

Don’t attempt to engage four-wheel drive on a part-time transmission Land Rover while the rear wheels are spinning.

Don’t attempt to engage the centre differential lock on a full-time transmission vehicle when any of the wheels are spinning or when turning a tight bend.

Don’t engage low range on the move on any model.

Don’t engage four-wheel drive on a part-time transmission Land Rover, or the centre diff lock on a full-time transmission vehicle on the road except when the road surface provides insufficient traction, such a muddy surface, ice or snow.

Don’t allow the engine to labour in too high a gear for fear of stalling.

Telephone: 01363 82666


Goodwinch Ltd, Oakleaf Way. Gunn. Barnstaple. Devon. Ex32 7NZ

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