River crossings are a fact of life for any serious offroader, particularly here in Marlborough.  So at the risk of sticking my neck out I thought I would pass on some of  the things I have learned over the years. 

1. Preparation of vehicle,
2. Assessment of crossing - where to cross, to go or not,
3. The actual crossing,
4. Post-crossing tasks - drying brakes, carpets etc. and checking diff oils

This month I will look at vehicle preparation - simple modifications  which can make crossings safer. There are several things to consider, all concerned with water entering where you don’t want it.  It is not wanted in your air intake, in your electrics and electronics, in your engine, transmission and differential oils and not really desirable in the cockpit.

    First have a look at the breather pipes in your front and rear axles. These are designed to prevent a build up of pressure in the differential and axle which could force oil past the seals.  They are small pipes attached to a fitting in the axle or diff cover and often terminate in the chassis rails or cross member. If the diff seals are located in the diff itself (as in the front diff of my Nissan), rather than at the axle housing extremities, there will also be a short breather pipe between the diff and the axle. Unfortunately the terminations of the axle breather pipes are often not high enough to prevent the entry of water in a river crossing particularly when you consider the “sucking effect” which occurs when a hot diff meets a cold river.

   So your first job is to extend these pipes as high as possible. On my truck I have extended the rear pipe so that it tees into the front pipe and then terminates high up in the engine compartment in a “U” fitting thoughtfully provided by Nissan. (Why didn’t they do the same at the rear?) You can fit a cheap in-line fuel filter instead if worried about dirt entering.  Make sure you leave enough slack in the pipe to allow for axle travel. The short breather pipe between the diff and the axle, if fitted, can have a tendency to come adrift so check that the clamps are tight and the tube has not hardened with age.  Some factory breather pipes use a check valve but I would not rely on these.

Water entering the engine through the air intake is apt to cause major damage, particularly with diesels, as the piston tries to compress incompressible water. (aka "hydraulicing") A snorkel, though quite expensive, is cheap insurance if you are planning any serious water work i.e. if it is deeper than your wheels.  Petrol engines with carburettors are more likely to stop before any serious damage is done, but who wants to stop in the middle of a river deep enough to cause problems, so fit a snorkel to petrol engines too.  (If you are wondering why peopleturn their snorkel tops backwards when in the bush - it is to stop them being caught up on branches and being filled with leaves.)

On the subject of petrol engines, have a good look at the electrics - where they are mounted and how they are protected.  You can’t do much with the position of distributors unless you replace them with a totally waterproof electronic unit or one mounted inside.  My distributor is mounted quite low but has not caused any problems so far even with water over the bonnet.  I do make sure that the HT leads and the rubber boots are in good condition and I always put a thin layer of thick grease under the cap where it fits on the distributor body. I have recently replaced the points with an electronic timing unit which should help. Some people (Landrover owners?) suggest that the distributor should be encased in a 1 cm coating of thick grease but I have never gone to these extremes. Others suggest that dielectric (non-conductive) grease be used around the top of spark plugs and in electrical connectors but I have never bothered - should work though.
Coils should be mounted as high as possible and a mastic gun can be used to good effect to seal the terminals and the HT lead outlet.  I once tried silicon spray with disastrous results - the HT lead became so slippery it kept sliding out of the terminal.

With petrol-engined vehicles I consider a blind or tarpaulin placed over the radiator grille essential for any crossing more than a couple of feet deep.  I just use an old plastic sheet with a hole cut out where the bonnet catch goes.  The blind prevents water from being thrown everywhere by the fan and helps create an air pocket around the engine thereby protecting the electrics and electronics from water.  I am often surprised how dry the engine is after using such a blind. Diesel-engined vehicles can also benefit from a blind - they have alternators too! Most vehicles have flexible plastic fans these days and it has been known, particularly with fixed rather than viscous-clutch fans, for the blades to be drawn forward by the water so that they chew up the radiator.  So if in doubt, fit a blind.

Next ensure all grease points - drive shafts, steering, knuckle joints etc. are fully greased - use a water resistant grease such as that sold for boat trailer bearings.  If you have an electric winch fit a waterproof cover to it , or at least place a plastic bag over the solenoid pack. And, finally, if you are really serious remove the carpets - if water does not come through the door seals it can come through the fresh air intake when you are in over the bonnet!.

 And take some basic recovery gear especially if you are alone.  If you haven’t a winch, and even if you have one, take a hand winch or a hi-lift jack (which can be used as a winch as well as a jack), plenty of rope and shackles and don’t forget a snatch block (or two). A hi-lift jack is useful for jacking a vehicle off boulders but consider where you are going to place the jack - it is helpful to build solid jacking points into your bumpers or winch mounting, and don’t forget a solid baseplate. I have found a crowbar very handy for the same purpose, as well as moving boulders out of the way before I cross.  I carry the crowbar in 37 mm internal dia  PVC tube slotted in behind the winch.  I had to shorten the crowbar slightly so that it does not project beyond the sides of the vehicle. You can get standard end caps to fit this size tube which makes for a neat job. And if you are really serious a front diff lock can be a  lifesaver when you are trying to climb out  of the river up a loose bank and the back of your truck is semi-floating and being pushed sideways by the current. Finally a long length, 30m or more, of small diameter (8 or 10 mm) rope can have a multitude of uses such as getting a line to a stranded truck or belaying a person testing a crossing on foot.  

I knew I was tempting fate. In the first part of this series I stated; “Alternators and starter motors although often mounted low down do not seem to suffer as much from river crossings as you might expect, at least in my experience.” Well on the night before I was due to take off with the boys to South Westland my alternator packed up!  Can’t really blame that on river crossings though.
I also had some useful feedback and advice from Mark Shepherd  on Part 1. Mark  writes:
I had some water problems with the old petrol Nissan I had, (My first trip was Lake Daniels) I had spent days preparing for it but totally overlooked the electrics from a water point of view, hence the first decent puddle was the end of the trip for it. I spent the day with Richard in the Rangie, which had problems on the day also. It had been raining for the week before and rained the whole day we were there as well.

My solution was:

1) New rubber boots for both ends of the spark plug leads with a liberal coating of Vaseline.
 
2) A windscreen sealant put around the rim of the distributor. One it has some heat resistant quality’s, and two it remained pliable and therefore had good resistance to vibration. It never leaked.

3) The coil was mounted on the inside of the wheel guard right at the front of the vehicle, directly in the path of any water flicked off by the fan. The solution was a 2-litre soft drink bottle. (presumably the plastic sort - Ed) The top was cut off just at the end of the taper. The top was kept. The coil and its mounting bracket were installed in the bottle with the bolts holding the bracket protruding through holes drilled for that purpose. Said holes were sealed with the rubbery windscreen sealer. Wires and distributor lead were fed through the tapered top exiting through the now removed screw lid hole. The tapered lid was spread liberally with more windscreen goo and jammed back over the remaining bottle. When the goo sets the lid is sealed against water entry but is reasonably easily removed if needed. The holes where wires and leads exit were also sealed.

The Result
The result was a truck that now did not mind getting its feet wet. I made several crossings of the Awatere on one river trip and she never missed a beat. 2 or 3 crossings were deep enough, with the current, to have water over the bonnet and over the upstream mudguard. She never faltered. I did always, though, use a cover over the front.

Just a word of warning with snorkels, they are only as good as the technician who fits them. If there’s a leak where there should not be, you may still end with a hydrauliced engine. If you can avoid deep water crossings, do so is the best advice!!

Factory waterproofing

Mr Toyota-San appears to have some experience with 4WDs. There are a lot of little things on my Cruiser, and I am sure on others of its vintage, that appear to be factory fitted. Breathers for diffs and gearboxes are factory fitted - all with a “check valve” that appears to work. I have never had water in any of the gearboxes (Yes I do check!) I have had water in the diffs, but have not had any since front and rear axle seals were replaced. The Awatere trip was my last watery trip. The Acheron, being quite bouldery had me backing off in a few places in bumper depth water but I had no water problems. The breathers end just above chassis height front and rear. Mr Toyota-San recommends a wading depth of 600 mm. (As does Nissan-San - Ed)

Other factory modifications

He has also fitted “engine stops” on the engine something harder than you should, and the mounts let go, the radiator stays intact. Plastic sheeting inside the door panels ensures water may fill the door, but it does not flow inside. There’s a little box under the bonnet for running those extra wires from radios, spot lights etc., with a diagram showing, which connections are what. Depends if you want the device on all the time, only with ignition, or via a switch. Very handy, for the CB, compressor and the like. I could go on but I won’t.
[Thanks Mark. Another tip - before sealing your coil as Mark suggests, or when just using a mastic gun, is to run a lead from the secondary terminal of the coil to a termination inside the cab or other convenient location before you apply the mastic. If you do this you won’t have to unpick the mastic when you want to connect a dwell meter or engine analyser to this terminal when tuning the engine.