Land Rover Discovery Maintenance and Upgrades Manual, Series 1 and 2 E-Book

Ralph Hosier

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch

Veröffentlichungsjahr: 2014

Beschreibung

Based on real-life experiences and written by expert authors, the books in the Maintenance and Upgrades series from Crowood will help owners develop the workshop skills needed for the maintenance and repair of their cars, and give guidance on possibilities for improvements and upgrades to performance. With step-by-step instructions and safety information throughout, this book is a valuable technical resource for owners of the Land Rover Discovery, Series 1 and 2. Illustrated with over 300 photographs, the book covers sourcing parts and tools; common problems and solutions, covering all engine types, including Rover V8 and diesel engines; service and repair; improvements for wheels and tyres and detailed specifications. This valuable technical guide for owners of the Land Rover Discovery, Series 1 and 2 will be of particular interest to home and professional mechanics and Land Rover enthusiasts, specialists and owners' clubs. Illustrated with over 300 colour photographs.

Leseprobe

MAINTENANCE AND UPGRADES MANUAL

Land Rover Discovery

Series 1 and 2

Ralph Hosier

THE CROWOOD PRESS

First published in 2014 by

The Crowood Press Ltd

Ramsbury, Marlborough

Wiltshire SN8 2HR

www.crowood.com

This e-book published in 2014

© Ralph Hosier 2014

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publishers.

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN 978 1 84797 827 1

Disclaimer

Safety is of the utmost importance in every aspect of an automotive workshop. The practical procedures and the tools and equipment used in automotive workshops are potentially dangerous. Tools should be used in strict accordance with the manufacturer’s recommended procedures and current health and safety regulations. The author and publisher cannot accept responsibility for any accident or injury caused by following the advice given in this book.

Acknowledgements

The following people allowed me to photograph, and in some cases disassemble, their cars: Nick, Franc, Diana, Jill, Ranen and Rebecca. Thank you all very much. The biggest thank you goes to Diana, for support and inspiration in all things.

contents

1

introduction

2

history

3

using the Discovery

4

common problems and solutions

5

servicing – simple jobs

6

servicing – big jobs

7

non-standard techniques

8

repair

9

improvements

10

where to buy parts and tools

11

specifications

12

contacts

13

appendix i: Discovery 1 Technical Service Bulletins (TSB)

14

appendix ii: Discovery 2 Technical Service Bulletins (TSB)

glossary

index

The Discovery’s proportions were very carefully engineered to make it look smaller than it was, note how much the rear door slopes forward at the top.

1

introduction

The Land Rover Discovery is a fantastic go-anywhere vehicle, unless it’s broken down on your driveway. If that happens then chances are it is because of poor maintenance. The Discovery 1 is based on the Range Rover Classic, which first went on sale in 1970, so some parts are from an age where extensive maintenance was simply routine, and whilst the Discovery 2 didn’t need its distributor cap replacing every year, its added complexity brings with it a few more jobs to do.

A Discovery and the Range Rover that inspired it, undaunted by rough roads and poor conditions.

Good maintenance makes these superb vehicles a joy to own; poor maintenance makes them a nightmare. Knowing what to look for is the key to keeping your car working, but sadly the usual workshop guides miss a few things out. This book is written largely from personal experience and some lessons I learned the hard way so hopefully you don’t have to.

I have been enjoying these cars since they first appeared, having owned four Series 1 and two Series 2 Discoverys and worked on a great many more. I’ve used them for everyday commuting, the school run, moving building materials (750kg pallet of bricks does just fit in the back of a 200 with the back seat out!), towing my race cars all over the country and off-roading trips through mountainous valleys, rivers, deep mud and glaciers. My Discoverys have rescued people from floods, shipped families to weddings, carried furniture home and also been used for pure entertainment at ‘pay and play’ off-road days. And that’s why I think they are brilliant.

I have always done all the maintenance, and a few modifications too, myself. That way I know the job was done the way I wanted it, plus when working on my own car I learn more about its condition, which sometimes helps to stop problems developing. One such problem is the scourge of fake parts, which can make a mockery of home maintenance and lead to dire consequences. So please read the section at the end of this book about where to buy parts and tools from to avoid any nasty surprises.

That’s me, your author, clearly pleased with my day’s ‘work’ with my ’94 Discovery 1 V8.

I have also included a glossary at then end of the book, which hopefully should explain any technical jargon that’s crept into the book.

With the right knowledge, tools and quality parts, maintaining these great cars is very rewarding. Being able to fix things yourself is very liberating, plus it saves a ton of money on labour costs.

WARNING

However, before you read on I must give you a word of warning: working on your own car can be dangerous. Many parts are sharp or heavy and could very easily injure you, but also if you make a mistake then you could turn the car into a death trap. Making mistakes on things like suspension or brakes could lead to loss of control and a potentially fatal accident.

So please ensure you have the right skills to do the job before you start. If in doubt, get professional help. You can also learn the necessary skills at one of the great classes run by local colleges, with the added advantage that you will meet other like-minded enthusiasts who might just be persuaded to come round and help with the tricky bits.

Even if you have prior knowledge it is often worth retraining and expanding your skills. I am a professional automotive engineer with decades of experience, and I still constantly study and undergo training. Never stop learning.

I have made every effort to ensure everything in this book is correct, but no one is perfect. If you spot an error then let me know. Please do not take this book to be superior to the official workshop manuals.

Where I show a technique that worked on my car there is no guarantee that it will work so well on your car. Land Rover changed detail specifications on a regular basis and made some variants that were poorly documented, particularly those for some specific foreign markets, and of course anything made by the Specialist Vehicle division.

It is amazing just how much can be done by the home mechanic. Here I’m checking and setting suspension geometry.

2

history

It is remarkable to think that the Discovery was launched way back in 1989, designed with real purpose in mind: to bring active families to the scene of their adventure. Capability was the key, being equally as good as a family estate car as it was an off-road work horse. The interior was brilliantly appointed by Conran Design and the exterior was styled to make it look smaller than its big brother, the Range Rover, even though it was built on a near identical chassis. In fact, not only is the chassis borrowed from the Range Rover Classic (RRC), a design first launched in 1970, but the front bulkhead, windscreen, door frames and the complete engine and transmission system was too. Other parts came from the Rover parts bin, including Sherpa headlights, Metro indicator stalks and Montego van rear lights, which all helped to bring production costs down.

The visual trick of making it look smaller was done by making the back door stop short of the rear bumper and sloping it forwards. It’s not obvious but it actually slopes quite a lot. All this was done to combat the effect of the higher rear roof, designed to make it easy to get bicycles and other ‘adventure’ equipment in. It is also quite useful as a work horse: with the rear seats out I have been able to forklift a full-size industrial pallet into the back carrying three-quarters of a ton of bricks. Safety was important in the new design: the body shell had a welded-on steel roof and big rear pillars, giving much better rollover protection than either the Range Rover or Defender, and a welded-in steel rear floor pan, which all adds up to a much stronger shell. The downside is that all that extra steel, about 200kg of it, adds weight when compared to a Range Rover of that era and most of it is quite high up. For that reason early Discos tend to roll more in corners, which soon lead to the introduction of anti-roll bars.

On arrival the Discovery had the 200Tdi diesel and 3.5 V8 petrol engine (initially with twin SU carburettors, then subsequently Lucas fuel injection), the LT77 five-speed manual gearbox and LT230 transfer box and the two-door body. The four-door version was launched in 1990 and subsequent years saw the specification gradually improve to include things like electric windows, central locking/alarm/immobiliser, ABS and the ZF4HP22 four-speed automatic. I think those very first cars had a beautiful simplicity to them, but they are getting very rare now and becoming quite collectable.

The Sherpa headlights have a slightly unfair reputation. If kept in good condition and with quality modern bulbs they are perfectly adequate.

Some enthusiasts were concerned that the introduction of anti-roll bars would limit axle articulation. Here my long suffering ’94 model suggests there is nothing to worry about.

The face-lifted Discovery Series 1 became known as the 300, after the 300Tdi engine that was introduced at the same time.

In 1993 Land Rover introduced the 4-cylinder petrol 2.0Mpi engine because some countries such as Italy had severe taxes on vehicles over 2 litres. Also the Discovery Commercial was introduced that year – a very useful two-door car with no rear side windows and a slightly different floor pan at the back with more usable space.

The V8 was enlarged to 3.9 litres in 1994 and had anti-roll bars fitted front and rear, which reduced roll in corners very noticeably. Some earlier cars had the anti-roll bar mountings on the chassis but no bars were fitted, so these cars can be upgraded fairly easily.

In 1994 the 300 Series facelift arrived and the diesel engine was revised for better refinement. Named 300Tdi, it was now attached to a new, stronger R380 manual gearbox. The rear indicators, side and brake lights were moved to the bumpers to comply with new regulations that required the lights to be visible when the rear door was open, but the original side and brake lights were retained in the clusters too, giving double the number of lights. The headlights were enlarged from the original Sherpa units and were significantly brighter.

The interior was revised, the dashboard became clearer, and the heater became a dual-zone unit with rotary controls that were easier to use and more reliable.

Camel Trophy special editions were made from 1990 to 1997. All were used in the competition and have had a hard life, but all were refurbished before being sold on and have a strong following, which has boosted values. The cars had a full roll cage, large roof rack, front winch and underbody protection as well as many detail changes. Honda made Discoverys for sale in Japan, called the Honda Crossroad.

The last year of production for the Series 1 was 1998, with the Safari and 50th Anniversary models introduced as a final flourish. By then the old Range Rover chassis was beginning to show its age and so a new project began to completely redesign the Discovery, and although the Discovery 2 looked very similar to the original it was almost completely different. The only body panel carried over was the back door and even that had different electrics and trim.

The body was extended at the rear behind the axle to provide a much bigger boot space and to allow for the forward-facing third-row seats, which also benefited from proper three-point seat belts.

Every aspect of the Discovery 2 had been adjusted in some way, making it essentially a completely different car to the Discovery 1. The road-holding was significantly improved with the option of Active Cornering Enhancement (ACE), which controlled body roll with hydraulic rams, while revised rear suspension with trailing arms (similar to the front axle but facing the other way) and a Watts link gave much better lateral location and made the car more stable at speed.

The V8 was heavily revised with larger bearings and a new intake system, and the diesel was now the mighty TD5 5-cylinder unit with electronic diesel injection. Gearboxes were similar to older models, the ZF auto now having electronic control.

A huge amount of engineering work went into the Discovery Series 2, where almost everything is different except the back door. The body is stretched behind the rear wheels to allow forward-facing third-row seating.

Refinement was improved, noise reduced and comfort refined, but all this was at the expense of weight and complexity. The Discovery 2 weighs approximately 300kg more than its Series 1 counterpart and has a vast array of electronic modules that all interact with each other, making some DIY operations a little more challenging.

The increased capability of the Discovery 2 was quickly noticed by the racing community and was raced in crosscountry rallies and extreme off-road events all over the world. Perhaps the ultimate incarnation of the Discovery 2 was the Bowler Wildcat, an out-and-out off-road race car that had a plastic body resembling a Defender but used Discovery 2 axles, drive shafts, gearbox, engine, dashboard instruments and a raft of other components.

Production came to an end in 2005 with just over 514,000 Series 1 and 2 vehicles made. Its replacement, the Discovery 3, was a completely different car with independent suspension and shared no parts with the Discovery 1 and 2 at all, but it capitalized on the image and reputation that the magnificent Series 1 and 2 cars had carved out and kept the engineering philosophy of practicality and capability.

Discovery 2 back seats are more supporting and safer than Series 1 items, with fold-down head restraints and three-point seat belts, plus headphone sockets and drinks holders, making it ideal for the little ones.

3

using the Discovery

This may sound like a silly idea for a chapter, but I have found a few things that make the Discovery that little bit more useful and reliable.

Washing the car First of all a note about cleaning: pressure washers can cause problems. They are fine if you stand a few metres away and use them to remove mud from the body panels, but that’s about all.

The trouble is that the very high water pressures cause damage if used close up. They force water into electrical connectors, through rubber seals and can even get into the rubber itself, causing damage to tyres, air springs and hoses. Never use a pressure washer in the engine bay for these reasons.

Problems may appear over time – water in electrical connectors will induce corrosion and it may be a few months after cleaning that you start to get intermittent electrical faults. Water in the tyres may unbalance them, which will get worse over time, and if there is a danger of frost the water may freeze inside the tyre wall or tread and start to weaken it.

Never pressure-wash oil leaks from gasket joints, as if the oil can get out, then high pressure water can get in!

After washing the car, take it for a drive to spin the water away from the brake discs, or they will start corroding quite quickly.

Wading Before going into deep water always test the depth using a long stick. If the water is flowing then avoid it – just 1 foot of fast-flowing water can knock you off your feet, and 3 feet of fast-flowing water will sweep the Discovery away too.

If the water isn’t a raging torrent but likely to be at or above headlight height, make sure your headlights are turned off for a minute before going in, or the cold water hitting the hot glass of the headlight may crack it.

The standard Discovery can safely wade half a metre of standing water, but post wading maintenance is essential on older cars to deal with leaking seals.

Also keep the revs down to prevent the viscous fan turning into a propeller and becoming damaged.

Seizing levers and switches If you don’t drive off-road very often, you may find that the transfer case levers seize up. It’s usually nothing serious, just a build up of road grime on the links, so it’s worth dropping it into low range and diff lock every so often. You don’t need to move the car, just move the levers. Then it will be ready and working should you ever need to use it.

It’s a similar story with switches: if a switch is rarely used the contacts can start to tarnish, as can relays. A common failure is the hazard warning switch, which often only gets used at the yearly MOT test. Switching it on and off several times usually brings it back to life. Operate all circuits once in a while to keep them working.

Big loads If you need to move a large object in a Discovery, such as a wardrobe, it is fairly easy to unbolt the rear seats to give full access to the rear of the car. The bolts protrude through the floor and the lower part of the bolt thread corrodes, so if it has not been done before then it’s worth getting a small wire brush on them and using a good dose of penetrating oil before trying to take them out. I found this out when I sheared one off trying to get it out. Subsequently I replaced the bolts with stainless steel items to prevent it happening again.

Child seats All Discoverys are great for transporting the family, but as the rear wheel arch intrudes into the corner of the rear seat, some child seats don’t fit. Just check the dimensions of the seat base before buying.

Avoiding rocks The lowest points on a Discovery are the differentials, so when negotiating rocks or other obstacles it’s handy to know where they are. On right-hand-drive Discoverys the diffs are in line with the driver’s left leg, so as long as you line the car up to avoid boulders going under your left leg you’ll stand a better chance of getting through. If your car is left-hand drive, you are less fortunate although you could entertain your passenger by asking them to direct you!

Towing When towing heavy trailers it is all too easy to make the car less stable. The most important factor in keeping the whole rig stable is keeping the back axle under control. The back axle has far more influence on stability than the front axle. So if you tow big stuff then pay particular attention to the rear tyre condition and inflation pressures (see below under Tyres) and make sure all the bushes and links are in good order. I found it to be most stable when the tow hitch was loaded at near its maximum recommended load. In a car without load levelling this results in the vehicle being slightly nose up. Never exceed the recommended maximums though.

Rated for a 3.5-ton trailer with overrun brakes, the Discovery is a superb tow car. Stability is excellent as long as the car is well maintained.

Hitching up a heavy trailer with a car that has load levelling rear suspension (seven-seater Discovery 2) is made a bit easier by setting the suspension on low, reversing up to the hitch and then raising the suspension to hook up. Also with long flat-bed trailers, loading and unloading can sometimes be easier if the rear suspension is on maximum height, thus tilting the trailer down at the back.

Turbo wind down After driving a Tdi hard, allow the engine to idle for a few minuets to allow the turbo bearing to cool down before turning it off. This prevents the oil in the bearing from cooking.

Tyres Tyre pressures make a huge difference to the way the Discovery handles, and tyre technology has moved on a long way since 1989, so some of the original tyre-pressure advice given then may be questioned. When fitting new tyres ask for the tyre manufacturer’s advice on pressures. For instance, depending on brand I usually run mine at around 40psi for most road work and up to 50psi when loaded near the maximum. Compared with the significantly lower pressures in the original handbook these gave me greater stability, even tread wear and slightly better fuel economy. For deep mud and off-road work I drop them to a lower pressure, maybe 30psi for green lanes and as low as 20psi for short runs through very deep mud. But don’t copy me blindly; ask for the tyre manufacturer’s recommendations.

Lay up and recommissioning Many of these cars will be left standing unused for long periods, which can seriously increase corrosion rates. Over long periods the oil film will completely drain from engine parts, gears and differentials, exposing metal to moist air. Many of these parts have a very thin surface hardening and when corrosion takes hold this layer can be ruined very easily, leading to rapid wear next time the car is used.

For this reason a car must be driven, even if it is for a short distance, regularly during the lay-up period. When a cold engine is started water condenses out of the exhaust gasses and pools in the exhaust system. As the exhaust pipe heats up eventually it gets hot enough for the water to evaporate, resulting in a temporary increase in the amount of white vapour coming out of the tailpipe. It’s important to keep the engine running until this phase has finished because stopping the engine before the pooled water has been driven out will rapidly increase exhaust corrosion. If it is not possible to run the engine during the lay-up period then you could put a few drops of oil in the cylinder bores, which should be dispelled by cranking over with the spark/glow plugs out when recommissioning. There are lay-up oils and additives that drain less readily for engine and gear parts, but this should be replaced with normal oils when recommissioning.

Brake pads can slowly bond onto the discs and the handbrake shoes can bond onto the drum. This results in the brakes appearing to be on but they will suddenly free off when pulling away. Unfortunately in so doing they will have lost some of their integrity and may fail soon afterwards. So always chock the wheels and leave the handbrake off.

Moisture will condense on metal panels every day as the temperature rises and falls; in normal use driving will draw air through the car but during lay up it will accumulate in cavities and floor mats. To prevent this ensure the storage area has some air flow through and is protected from rain. Avoid storing cars on grass or dirt, which generates huge amounts of moisture and will rot the underside of a car very rapidly.

When you pick up a new project car it is well worth taking the wheels off and carefully inspecting all the common problem areas.

4

common problems and solutions

There is no reason why a well-maintained Discovery shouldn’t be as reliable as any other make of car. Older Land Rovers had a reputation of poor reliability, but this was largely due to poor maintenance and miss-diagnosis of faults.

Faults should not reoccur – once a fault has been fixed it should stay fixed for a long time – if a fault keeps coming back then it was never really fixed in the first place, just masked. Even experts can make the wrong diagnosis sometimes. Second opinions on complex problems can often help, and a genuine expert will welcome a good second opinion, not fear it. Finding and fixing the root cause is vital, for instance if your car keeps flattening batteries then changing the battery won’t fix the electrical fault that’s causing the problem.

Although the first cars arrived in 1989 they are stronger than some modern cars. This unfortunate example was rolled several times without collapsing, and amazingly still drove.

Luckily some of these faults have relatively simple fixes, so in this chapter you will find some of the most common problems and a few simple solutions. The solutions are briefly described in this chapter so you can decide if you want to fix it yourself or take it to a garage. If you want to fix it yourself then some of the fixes are described in more detail in later chapters; the rest are described in the usual workshop manuals.

ENGINES

Land Rover engines are generally low powered so they can cope with heavy use for extended periods and with poorer specification fuels found in far-off lands. However, that robustness does depend heavily on good maintenance, something often neglected.

Head gasket failure – all engines Head gasket failure can happen to any engine, and it always has a cause that must be addressed before changing the gasket. If it has failed between a coolant gallery and an oil feed then oil will be forced into the coolant, forming a film in the header tank. If it fails between the coolant gallery and an oil drain hole then coolant will get into the sump, forming a mayonnaiselike emulsion in the rocker cover and a light grey sludge in the oil. If it fails between the combustion chamber and the coolant gallery then there will be clouds of white smoke (actually water vapour) when starting from cold, and it may blow coolant out of the pressure cap when hot. Temperature gauges are only a rough guide to engine temperature.

Even later engines, all dressed in plastic covers, are fundamentally traditional and simple units. No variable cam timing or multi-path compound turbo systems here.

It was found that the outer row of head bolts on V8s cause the head to tilt on the gasket and increase the likelihood of failure. That is why the torque setting for those bolts was reduced, and eventually they were deleted altogether.

If the failure was caused by overheating then the culprit may be a stuck thermostat, clogged cooling system or defective fan. If all that checks out correctly then it may be due to liner sinking, particularly on later V8s, or it may be due to a poor rebuild where inferior gaskets were used or the head bolts were not correctly torqued down. Whatever the reason, sort that out first before changing the gasket.

Groaning noise from front of engine Sometimes the steering pump (and ACE pump on Discovery 2 models) can make a bit of noise due to fluid cavitation. Using PAS fluid with the right additives is important, but some owners top up a leaky system with the cheapest fluid, which can cause a noise problem. To get rid of the noise, drain and flush the steering or ACE system with the correct fluid before refilling.

Do not use ordinary ATF or the ACE pump will start groaning; use PAS fluid of the right specification.

Petrol engines

The Rover V8 in 3.5-litre form, as fitted to the very first Discoverys, was almost indestructible. It may leak oil from the valley gasket, rocker covers and sump, but that’s fairly normal. It does need regular oil changes, however. Many cars are neglected and driven far too long on old oil, leading to tar build-up and possible big-end bearing failure, cam wear, tappet collapse, rocker shaft wear and worn bores. You must check an engine by starting from cold, and when you view a car open the bonnet and check the engine has not been warmed up before you start it. Often engines are driven for years with less than the full eight cylinders working. Even when working badly these tough little engines still work enough to drive the car, and that’s the beauty of not being too highly tuned.

The seller of this V8 swore it ran fine despite a ticking sound, but two bent push rods left it running on just six cylinders! The V8s keep going even when poorly maintained, which is why many are sadly neglected.

Coolant loss from water pump Water pump bearings wear, particularly if the car has ever lost coolant in its life; look for telltale coolant traces on the back of the pump pulley or a tendency to squeak from cold.

The solution is to replace it, unless you have a good workshop press in which case you might be able to fit a new bearing and seal.

Water pumps leak from worn bearings, eroded gaskets and corrosion under the hose connections.

Blowing coolant out or contaminating oil When the bore was stretched for the 3.9 V8 the cylinder liner was not held quite so well as in the 3.5 engine. It has a tendency to creep down, which in turn compromises the cylinder head gasket clamping and gasket leaks are then common. Engines with this fault are expensive to fix properly, although it has to be said the fault can usually be ‘lived with’ if it’s not too severe.

Changing the head gasket on any Discovery engine is reasonably straightforward, but before getting to this stage find out what caused the failure. Maybe the cooling system is struggling. Even thermostats have a service life.

The results of this problem are a tendency to blow coolant out, resulting in overheating, and in some cases a tendency to burn a bit more oil than usual, but if the coolant gets into the oil then the engine will quickly destroy itself. The same problem occurs on the Discovery 2 V8 engine – if the liners have sunk and caused the head gasket to fail then skimming the heads will NOT fix the problem. Either new liners have to be fitted or a replacement engine block found.

SU carbs can be made to run very nicely if kept clean and well maintained. If regular adjustments are needed then something is wearing out and should be investigated. Dashpot oil should be replaced if it starts going sticky.

Carburettors, poor running (very early Discovery 1) Carburettors on the very first Discoverys can suffer from old fuel clogging the small bores and also gaskets leaking. If the engine runs rough, it may be worth stripping the carburettors down, cleaning them out and rebuilding them with new seals and gaskets – this can transform an old engine. Moving parts wear, so items like the main barrel in an SU should be replaced if it exceeds tolerance; the same goes for needles and jets.

Idle quality and initial pull away are governed by idle fuelling, the throttle stop and by ignition advance. If the idle is a problem, check the ignition first, then adjust the idle fuelling and throttle stop to get it precise.

Check ducts are secure. To preserve the screw head, use a small socket on hose clamps and not a screwdriver.

Idle valves should be periodically removed for cleaning. Before refitting apply a drop of thread sealant (not thread lock) to prevent air leaks.

Fuel injection system, poor running and misfires The most common cause of faults on injection systems is electrical, particularly poor earth connections. A problem on high-mileage or old engines is injector wear, and they can clog up over time giving a poor spray pattern or reduced flow. If the seat is pitted, the injector may leak, resulting in black smoke and a misfire. Removing the injectors and sending them off for ultrasonic cleaning can help in most cases, although sometimes the injector is so far gone it will need replacing.

Air leaks between the air meter and engine will cause problems, so make sure all the hoses and small pipes are secure and not cracked.

Stalling and poor idle control Engines with the 14cux control system have an idle-speed control valve that can become clogged. The solution is to undo it and wash the end out with WD40 or similar, and extract the gunge from the housing. It may take a couple of attempts before it properly clears.

You can see from the soot pattern where this exhaust gasket was leaking. The gas passing the hole draws air into the exhaust system and makes the lambda sensor read too lean, causing the engine to run too rich in an attempt to compensate.

Higher-than-normal fuel consumption, poor emissions and noise from the exhaust If the engine uses lambda sensors then make sure there are no exhaust leaks on the exhaust manifold. If there are then change the gaskets. A leaking manifold on these variants reduces miles per gallon and idle quality, and can coke up the combustion chambers and foul the spark plugs.

Oil-pressure light stays on There are two possible causes. A common fault is that the oil-pressure switch has relaxed and comes on even at normal oil pressure. The fix is to fit a new switch, which is easy and cheap. If the oil pressure is genuinely slow to pick up then the main and big-end bearings may be worn. It’s a substantial job to change them but can be done at home if you know how. Whether you do it yourself or get help, change them before the engine starts rumbling and suffering real damage.

It is just about possible to change the main and big-end bearings with the engine in situ, but it is far better to take the engine out and do it properly.

Low power The camshaft is one of the first things to wear if the oil has been neglected. Symptoms include reduced top-end power but still reasonable low-speed pull, almost like having a restriction in the inlet, and a rattle on start-up as the hydraulic tappets pump up to compensate for the wear. These engines can run with only half the cylinders working properly, so often cam wear goes unnoticed for years. With fuel consumption becoming ever more important, if you are changing the cam then it may be worth using an improved profile. Using a milder cam (duration of 220 degrees or less) or retarding the cam a fraction can improve low-end torque and miles per gallon at the expense of topend power.

Changing the cam can be done at home but requires the removal of the radiator, sump, front-end belts, intake manifold and the front engine cover, so it’s not a small job. See the Repair chapter for details.

Wear on this cam lobe has reduced lift and as a result ruined performance. The follower has worn in sympathy and followers must always be replaced when fitting a new cam.

Engine runs but starts misfiring under load and will not rev After first checking the fuel system, the next possible culprit is the ignition system. If the coil is not charging up fully after each spark then it limits speed and power. This could be because the coil is damaged internally or the driver unit is malfunctioning. Check the earth wire from the driver unit on Discovery 1 models, as it tends to corrode where it’s attached to the inner wing.

A very common cause of ignition faults is the earthing. Check the earth studs for corrosion as well as the straps on the coil and also on the back of the cylinder head.

Rough idle and stalling Discovery 1 V8 distributors are very sensitive to degradation of the distributor cap terminals and rotor arm. Once these go the engine struggles to idle cleanly and then it starts to foul up the spark plugs and will stall when slowing down to stop. The distributor cap tends to foul up the terminals with a hard white deposit, which can cause the engine to lose power and stall at idle. If this happens when out in the wilds then simply scrape the deposits off with the edge of a coin. Dressing the terminals with a small grinding tool will restore them briefly, but as the corrosion eats into the terminals and widens the spark gap the cap will eventually need to be replaced. It is the same with the rotor arm, with hard black deposits forming on the trailing edge. Again these can be scraped off as a temporary fix, but eventually it will need replacing. I have also seen some new distributor caps loose their spring-loaded centre electrode, so check this is not loose or missing when buying a new cap.

This essential tool is ideal for gently clearing carbon deposits from old distributor caps and rotor arms without cutting into the soft metal too much. Every tool kit should have one.

2.0-litre Mpi The 2.0-litre Mpi petrol engine used briefly in the Discovery was taken directly out of the Rover road cars. It is a simple and usually reliable engine although performance is limited. A worn engine will make telltale rattling or tapping noises.

Make sure the cam belt is changed when due; it’s quite easy compared to other engines.

Diesel engines

Runaway – engine revs even with the ignition off (all diesels) Diesel runaway is the name given to an engine running on its own oil, which can be caused by excessive bore wear or worn piston rings that result in oily crank case gases being pumped into the intake through the crankcase vent system. A warm diesel engine will run quite readily on this oil-rich gas and even turning the ignition off will not stop it. If left to its own devices, a runaway engine will continue revving until it destroys itself or runs out of oil. Any make or model of diesel engine can suffer from this if sufficiently worn. If this happens, the only way to shut the engine down is to stall it. This can be a very frightening experience and has the potential to be very dangerous.

The crankcase vent system takes gas from the block into the intake via an oil separator. If the drain becomes blocked, oil will be burnt in the engine and could lead to harmful deposits in the combustion chamber or runaway.

Stalling is best done in a high gear. If the car is in motion then leave it in whichever gear it is currently in, because as soon as you dip the clutch the engine will rev up very quickly and may destroy the crankshaft and block. When safe to do so simply apply the brakes as hard as possible and bring the car to a halt in gear, this must be done as quickly as possible to avoid overheating the brakes, which could otherwise start to fade. If the car is already parked and in neutral then dip the clutch, put it in top gear, put your foot as hard as possible on the brakes and let the clutch out very quickly. Don’t let the clutch out gradually as it will simply overheat and slip. Obviously this will not work on automatic gearbox models.

The other way to stop a runaway is to collapse the air intake by squashing one of the air ducts, or pull off the breather tube to prevent oil going into the intake. This can be very dangerous as the engine could explode whilst you are working in the engine bay, so I really would not recommend it.

A slightly safer version is to use a CO2 extinguisher discharged into the air intake, which will remove most of the oxygen. Never use a foam or water extinguisher as any liquid breathed into the engine will cause it to fail catastrophically.

Smoke when cornering, due to oil in the intercooler (all diesels) All models have intercoolers and one of the common complaints is that of the intercooler filling up with oil. The result is that if you accelerate while cornering, for instance exiting a roundabout, the combination of side force and higher intake air flow draws the oil out of the intercooler and into the engine, resulting in a cloud of black or blue smoke and potentially a severe misfire.

The intercooler by its very nature causes oil mist to condense into liquid oil, which could be drawn into the engine at high loads. Taking it out and cleaning it removes the danger.

The oil deposit is caused by gas from the crankcase vent system condensing in the cold intercooler. That is not really a fault in itself, but if the oil level builds up too far than it can cause problems.

The solution is to remove the intercooler, maybe once a year or so, and clean it out, ensuring no cleaning agent is left inside when you refit it. If it fills quickly then this may indicate excessive crankcase vent gas flow, which may mean worn piston rings or cylinder bores. This should be investigated immediately as very high blow-by can lead to the engine inhaling enough oil to run on, causing it to rev up out of control (see last section).

This TD5 is leaking oil from the ducts, which indicates two things: there is oil in the intake and the hoses are leaking very slightly. This might be okay but should be investigated to be sure.

Smoke and loss of performance due to duct faults (all diesels) If your diesel engine has reduced power but doesn’t emit huge amounts of smoke and, other than the lack of power, seems to work, then it might be a problem with an air duct. The ducts between the turbo and the intercooler, and between the intercooler and the intake manifold, can fail, in which case you will loose boost and performance.

If the retaining clip weakens or corrodes through then the boost pressure can cause the duct to be blown off, resulting in increased turbo whistle. The obvious solution is to pop it back on with a new clip.

On older engines the rubber ducts will have become harder and prone to cracks – the bigger the crack, the more boost is lost. In this case it’s worth replacing all the rubber ducts, because if one has failed then the others will not be far behind.