Four Wheel Drives - Faults and Problems Four Wheel Drives suffer from all the common car faults and problems. The good news is that they are usually stronger and more rugged than cars. The bad news is that there are more mechanical bits - more to go wrong. Some owners think that a 4WD can do anything and needs no maintenance but this is not the case. Beware of vehicles that have been overloaded, worked hard and neglected. General There are general points to check and danger signals to watch for when buying a four wheel drive. A full maintenance record is a good start, particularly on the more complex luxury four wheel drives; ring up the workshop and see if they have any comments about the car. Chassis The chassis can reveal overloading, hard driving and neglect. Chassis outriggers may crack where they join the main frame if the vehicle is overloaded and driven hard on rough roads. "Rock climbing" can leave dents in chassis cross-members. Steel chassis are susceptible to rust. Check particularly the front and rear cross-members and any low points. Check that all drain-holes are clear or dust and mud can find their way in and hold water. Interior Check under the carpets for damp and rust. The 4WD may not have been dried out well if it has been wading. Mechanical Many a four wheel drive requires more maintenance than an ordinary car, however access is usually easier due to the vehicle's height and general size. There can be two axle differentials, gearbox, transfer case, steering swivel-housings, steering box, steering idler, engine that can need their oil levels checked regularly and all are susceptible to water contamination from wading. Did the previous owner check them all and change them regularly? Oil that is contaminated with water has a milky-brown colour. What about the universal joints (there could be six or more) and the prop-shaft slip-joints? Rust Check for rust around the bottoms of doors and tailgates where water and mud may collect and drain holes can get blocked. Any semi-enclosed space is a risk - e.g. chassis members particularly where mud gets thrown up and collects. Many four wheel drives are used for towing boats and salt water is bad news! There may be tell-tale signs of corrosion on steel wheels, brake backing plates and springs. Suspension Heavy loads and corrugated roads can lead to sagging springs. Sagging springs can cause hammering of suspension bump stops and lead to chassis damage. Heavy front-mounted winches make this more likely unless stronger front springs are fitted. 4WD shock absorbers (dampers) have a very hard time. Look out for fluid leakage, although a test on a dynamic test rig is the only way to be sure of the shock absorbers' health. Are the shock absorber mountings and the bushes sound? Conversions Converted four wheel drives need to be very carefully checked; it is difficult to modify a 4WD and still end up with as balanced a vehicle as the original - possible but difficult. Is the vehicle registered as it currently is? Check engine type and number etc. carefully! Does the 4WD have a valid engineer's certificate? If a bigger engine was fitted, can the cooling system, transmission, brakes etc. handle the extra performance? Is it easy to access the distributor, oil filter, spark plugs etc. for regular servicing? Was any re-wiring done neatly or is it an electrical fire in waiting? Insurance companies are suspicious of non-standard vehicles. Particular Makes: Daihatsu Daihatsu [problems and faults] Ford Some reports/ rumours of cam drive tensioner problems on early sohc Explorers c1997. Jeep Jeep [problems and faults]. Land Rover See also Land Rover problems. Engines: 200 series The 200 series 2.5L diesel engines (Defender, Discovery) have a reputation for chewing up their timing belts which then causes valve damage. It is important that the belts be replaced within the recommended interval. (The later 300 series engine is supposed to have cured the problem.) Timing belt failure can also be caused by oil leaks from the front of the crankshaft or by the entry of water if the wading plug has not been fitted for water crossings. Engines: 3.5L V8 The engine is generally strong provided that it is well maintained. The oil must be changed regularly or camshafts, valve gear etc. suffer. Gearboxes: full-time 4WD The full-time four wheel drive gearboxes can be abused: The centre diff' lock should be engaged on loose surfaces otherwise excessive wheel slip can cause damage to the centre diff'. The viscous coupling transfer case (later Range Rovers) is more idiot proof. Make sure that the correct oil has been used in the transmission! Range Rover Classic (1970-1995) The vehicle is often overloaded and driven fast on bad roads because of its good ride. This can lead to chassis cracks and even to cracks in the back axle. Land Rovers Series One - Three (1948-1984) We are talking about vehicles up to 50 years old here! Rover Axles The half-shafts on the "Rover" style differentials are weak and frequently fail, particularly on the heavier, long wheel base (109") Land Rovers and on vehicles fitted with larger engines. The good news is that regular inspection can be an effective preventitive. The Salisbury axle fitted to S3 LWB's is very strong. Oil Seals Hub oil seals tend to leak, particularly if the axle breathers get blocked, but they can leak anyway - not good for the brakes. Look for oil "sprayed" on the inside of the tyre(s) or oil dripping from the bottom of the brake backing plate. There is an oil seal between the gearbox and the transfer case. If this fails, oil can move from one to the other without any external sign. Check the levels regularly. Mitsubishi See also Mitsubishi faults. Pajero Engine V6 Early V6's tend to run hot. This can lead to cracked heads and burnt exhaust valves. So avoid LPG conversions. Pajero early Gearboxes The gearbox on the first Pajeros had a weak 5th gear overdrive which could fail, particularly on LWB Pajeros used for towing. Survivors have probably been fixed by now. Nissan 3 Litre Turbo Diesel GU Patrol John R' writes [11/2000]:- Nissan have yesterday recalled the 3.0L Patrol. This is to uprate oil capacity in the engine to 8.2L, an 2.5L increase, also "oil delivery characterisitics" (new control pressure valve). Nissan claim for long term durability of the engine the mod's must be performed. Also from around the traps, the 3.0L engine is proving very unreliable, with Nissan have shortages of parts. 1. Fan belt idler bearing, either seizes or sheers off (both mine and my brother's have done this out on a track. 2. AC compressor seizes - mine did when the car was 3 days old combined with 1. 3. Front splash tray in front of the engine snaps off when you are 4wding. Nissan have no stock of any of the 3 in the country. My Patrol (one of the first registered in Australia and featured on [4wdonline]) has now been off the road and sitting in Nissan for 5-6 weeks total since it was purchased in April. Nissan au replies that: The 3.0 litre turbo diesel Patrol is undergoing a "service programme" (not a recall) which involves modifying the characteristics of the engine oil circulation. "This programme has been initiated in the interests of ongoing customer satisfaction and continued product reliability and will be carried out free of charge to the customer." There are no problems sourcing parts. Patrol Some 1990s 4.2 litre Patrols had head-cracking problems; welding could be successful. The petrol engines on MQ Patrols get tired and start to blow smoke at about 150,000km but the diesel engines are said to be particularly reliable. Rust is the big enemy of old Nissan Patrols. The vehicles have a reputation for general simplicity and toughness although the bodies develop lots of rattles and groans. Standard springs sag. Toyota See also Toyota problems LandCruiser Some diff' input shaft bearings have worn prematurely. Check for excessive play on the diff' input shaft and listen for diff' noises - front or rear. Hub oil seals can leak. Check for oil on inside of the tyres or dripping from brake backing plate. (The axle breathers may be blocked.) LandCruiser 80 Series The C-pillars (on early vehicles especially) have been known to crack - roughly level with the lower edge of the windows. Open the rear passenger doors and check the pillar carefully. The alternator is mounted low below the air conditioning compressor. It can easily become clogged with mud if wading in muddy conditions. Full-time four wheel drive vehicles must be fitted with four tyres of the same rolling diameter or the centre differential will suffer excessive wear. Go to the mechanical matters page

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