TECH / Vehicle Service  

Text Box:                      OFF ROAD VEHICLE SERVICE A vehicle operating in the off road environment is subject to far more severe conditions when compared to on road operating conditions. Dust, water, vibration, shock loads etc are all present in far greater proportions. Most 4wds do a remarkable job of resisting everything the off road terrain can throw at them, but they won’t do it forever. Some things need to be serviced or breakdowns and the associated inconvenience and costs will follow as sure as night follows day. Here we will look at some of the service-related points beyond the usual oil, radiator coolant, tyre pressure checks that we all should be doing! Quite a few of the following procedures can be done by anybody that is handy with tools and has a jack AND safety stands (both these can be bought at very reasonable prices at K Mart or similar). Also, buy a service manual for your vehicle from a bookshop or parts warehouse. It will be invaluable for adjustment information and so on. Guys that say they don’t need this type of information are dangerous and should be regarded as one would a dog turd. Radiator Hoses Modern hoses are made of a silicon based artificial rubber. They give very little trouble but it’s worthwhile checking them. The top hose is subject to higher temperatures and is most likely to fail closest to where it joins the cylinder head because that’s where the vibration is. Check for soft spots in the hose by squeezing. Look for cracks. Contrary to popular opinion, spring-type hose clamps are actually better than worm drive clips because they maintain clamping pressure as the hose shrinks with age. Drive Belts Most off road vehicles have multiple V-type drive belts for water pump, alternator, power steering, and air conditioning. Drive belts have a finite life, and belts on diesel engines usually wear quicker than on petrol engines due to the greater amount of torsional oscillation a diesel engine crankshaft has. Water, dust, heat and bad adjustment also wear belts and there is plenty of that. Belt life on road is usually around 30,000km for a diesel and more for a petrol. Off road it’s less. To properly inspect belt condition requires removal of the belt, although it is possible to get a rough idea without removal in many cases. Most belts are internally toothed, and the first sign is usually cracking in the tooth root. Replace the belt if you see even the tiniest of cracks, they only get worse. Manufacturers have a belt tension specification, but a rough guide is 10mm deflection with a firm thumb push. Belt tensioner bearings get a hard life so give it a spin and listen for noise and roughness. Replacement bearings can be fitted in some cases, use a C3 graded bearing. Alternators Continual dunking in muddy water dramatically shortens alternator life in three ways: 1) it gets into the bearings and they tear themselves to bits, 2) it blows the rectifier (in the case of alternators with internal rectifiers) by allowing a short between the slip rings. Either or both things happening is VERY expensive, 3) the brushes get stuck in their holders and lose contact with the slip rings. Once a year, remove the alternator and give it to your favorite auto sparky (disconnect battery first). Likely all it will need is a set of bearings and brushes (cheap) and away we go again. You can also get him to fit a dash switch to cut the field coil circuit when entering boggy holes, this will save the rectifier but you have to remember to turn it on again. Starter Motors. Same as alternators, they hate being under water. They usually develop erratic habits and require a thump to jerk them into life. If you drive an auto, a push start is out of the question. Remove it once a year along with the alternator. Again all they usually need is bearings, brushes, a good clean out and lubrication. MUCH cheaper than a new armature. Radiators They can fill with mud, and the longer you leave it there the harder it sets. Hot motors equal blown head gaskets, cracked heads and possibly damaged pistons. Clean them out with a garden hose and a strong detergent, NOT a water blaster. Water blasters fold the fins over… presto, you just blocked your radiator! Fuel Systems Many fuel tanks have a drain plug. Grab a suitable container and a spanner, put out your cigarette, and drain out a litre or so. You might get a surprise at what comes out! Fuel filters should be replaced every 30,000km or so, and for diesel engines it is vital. Water getting into a diesel injection pump or injectors can actually destroy not just the pump and injectors, but the pistons as well! Injected petrol engines develop injector problems, misfires and spark plug failures. Carbureted engines misfire, destroy sparkplugs and over the longer term the carb body corrodes. All expensive. Brake Systems. Drum brakes hate sandy or muddy water in them. It tears the linings up and radically reduces the service life. Disc brakes seem to survive better possibly due to their self-cleaning action. Not much you can do about the muck getting in, but a periodic drum removal and hose-out will help. DON’T blow out with compressed air, brake dust is a health hazard. Change the brake fluid once a year and you will almost never have fluid leaks at the cylinders. DON’T push the pedal all the way to the floor when changing fluid, put a bit of 4x2 under it to limit the travel. Wheel Bearings 1 Tapered roller type. Water can get in through the hub seal and damage the bearing. First, read your service manual. Next, remove the hubs, seals and bearings. Water present will discolour the grease and the bearings will be showing corrosion and rust staining. Really bad cases the bearings will be a black colour. Clean out the hubs, new bearings. Grease according to the service manual information. Fit a new seal. Here’s some little tricks: Fit a Speedi Sleeve to the shaft for the new seal to run on. They do a great job of stopping water and corrosion because they are stainless steel. Also, put a good dollop of marine grease around the seal and just inside it. It seems help to stop any water that may sneak in. Assemble and adjust the bearings according to the service manual and don’t listen to any person that says differently. Wheel Bearings 2 Sealed ball type. These bearings generally can’t be serviced, get noisy and must be replaced, although it’s possible to regrease them if you can pry out the seal without destroying it. They have a great service life, but water and shock loads can finish them off. When replacing follow the service manual. Smashing outer races with big hammers can lead to case hardened steel shrapnel entering delicate parts of your anatomy, causing holes which leak blood. When buying replacements buy the wheel bearing kit, not just a “bearing that fits”. The wheel bearing is sometimes a specially graded bearing for the application. Diffs As we all know, they can get water in them turning the oil a nice creamy colour. Need to check diff oil frequently. Raised breathers are a step in the right direction. Plastic airline tube (6mm) inserted into the cut rubber hose is a great help here along with an 90° eighth gas elbow and a pushlock connector for some IFS Toyota front ends. Some cable ties and it’s done. Apart from the breather, water can enter through the pinion seal and in some types of axle, the wheel bearing seals and axle shaft seals. Pinion seals can be replaced, again a good trick is to fit a speedi sleeve to the pinion yoke. Follow the manual regarding pinion nut torque, loose pinion nuts destroy diff gears, tight pinion nuts destroy diff bearings. Make a yoke spanner by drilling two holes in a 600 x 60 x 5mm steel bar and bolt it to the pinion yoke to hold it. Check with the manual for the correct oil. If you have fitted an aftermarket locker or limited slip you must use the oil the maker specifies. Transmissions and Transfer Boxes. Same as diffs, they can get water in them and need to check frequently. Breathers or seals can allow water in. The story of a hot trans (or diff) hitting cold water and “sucking” water in is just that; a story like Snow White and the Seven Dwarfs. With a manual transmission the oil goes nice and creamy, same with autos but has a delicate pinkish shade. Replace with correct grade oil or fluid, and if it’s an auto, good luck! You will want to have the trans flushed and buy a service kit and fit it. Don’t hold your breath, autos are not very tolerant of water. If you find chunky metallic debris and clutch material in the filter, on the magnet and in the pan things will only get worse…. CV Joints Vehicles with IFS need regular CV boot inspections. Split boots allow grease out and water in. The result is an expensive bang and back to 2WD. CV boots can be expensive for some vehicles and aftermarket boots are a good choice most times. Be aware that CV boots are much more prone to failure in cold weather, so it pays to check them regularly. Beam axle CV joints are usually more durable but water can still get into them and destroy them. Once a year strip the front axle, regrease the CVs with the correct grease (check the manual) and fit a seal kit. Inspect the kingpin bearings, often they need replacement. A good trick on beam axles is to pack the ball housings chock full with marine grease. It really helps to stop water getting into the CVs Locking Front Hubs Need cleaning out and regreasing periodically. Don’t over-grease, replace the ‘O’ ring and gasket to stop water getting in. With manual type your fingers will thank you for some silicon grease on the ‘O’ ring…. Snorkels/Air filters Very important that the air induction tract is sealed against water ingression. With a snorkel fitted you can check with the engine idling, removing the “hat” and briefly placing your hand over the top of the snorkel. Engine speed should reduce. If not, find out where the leak is. Some advocate removing the one-way water ejecting valve in the bottom of some air filter housings. There is some truth to this as bits of twig and dirt may jam it open. However, the downside is that if you do manage to get water down the snorkel it will not be ejected and will go where no water should go. Best way is to retain it and service it periodically by cleaning the housing and valve seat. Air filters should be regularly serviced, foam types need the correct oil, not engine oil. Chassis Electrical Connectors They can get water into them and corrode causing high resistance and malfunctions. Separate them and spread a little silicon grease just inside the connector. Plug back together. This has a twofold benefit, 1) it helps stop water getting in, 2) it makes the connector easier to separate next time. Waterproofing spray can also be applied to the outer ends. Greasing Ideally the vehicle should be greased after any water excursion. However, most of us are not really into getting under a wet mucky vehicle late Sunday afternoon. But it is important to a driveshaft universal joint to have a regular diet of grease. While you are under there, have a look at your steering joints, make sure the tie rod end nuts are tight and rubber boots are ok. Look for bent steering rods, rocks stuck where they shouldn’t be, broken exhaust mounts, loose shock mountings etc. Look for leaks around the engine, transmission and transfer, around the hubs and brake cylinders. Shoot some CRC into your door locks and door hinges, you will amazed how well the doors work! Batteries Need to be securely fastened to the mounting tray. A loose battery can short out on the under-bonnet, providing you with the interesting sight of this ever-increasing patch of smoking paint fading into red hot steel. Secondly, loose batteries have a very short service life off road. Third, a battery finding it’s way into the fan blades is sure to get your attention.