Land Rover Discovery 1 300Tdi: Faults, Fixes and Upgrades
Workshop Guide
The Land Rover Discovery 1 with the 300Tdi engine is the first-generation Discovery with a 2.5 litre four-cylinder turbo diesel, on a separate chassis with live axles front and rear. Land Rover's workshop manual for the 300Tdi, Mpi and V8 Discovery covers vehicles from the 1995 model year onwards, and the Discovery 1 ended in 1998. This guide works through Discovery 1 300Tdi problems system by system, using that manual's own checks and figures.
The Land Rover Discovery 1, covered in this guide for the 300Tdi's 1995 to 1998 model years.
Key Takeaways
The 300Tdi Discovery 1 is a 1995 to 1998 model year car as Land Rover's workshop manual covers it; the standard engine has mechanical injection with no engine management ECU, and electronic diesel control (EDC) variants exist alongside it.
The manual for 1995 to 1998 model years lists ABS as an option. Its warning lamp goes out briefly after the self-check if no fault is stored, comes back on and stays on until the vehicle passes 7 km/h, which is normal; a lamp that stays on above that speed is checked at the exposed cables, the earth, the battery, hub end float and the fuses before fault diagnosis starts.
Steering shake is diagnosed in the 1995 to 1998 manual's order: wheel balance first, swivel resistance and condition tenth of eleven checks.
The timing belt is the top service item on this engine, and the 1995 to 1998 manual's schedule shortens for dusty atmospheres, high ambient temperatures and desert or tropical use.
Oil on the inside of a front tyre can come from the swivel housing seal or the hub seals; the 1995 to 1998 manual's level and grease checks identify the source before anything is stripped.
Scope
This guide covers the Land Rover Discovery 1 (no L-code) with the 300Tdi diesel engine, 1995 to 1998 model years. Where it cites "the workshop manual", it means Land Rover's manual for those model years (LRL 0079, 2nd edition) and the 300Tdi engine overhaul manual; each section that relies on them says so once. Vehicles built before the 1995 model year are outside that manual's coverage and have not been confirmed in this guide. It does not cover the 200Tdi Discovery 1, which has its own guide; the Discovery 2 Td5; or the Defender 300Tdi, which shares the engine and has its own guide.
The Discovery 1 ran from 1989 to 1998 and carries no L-series chassis code; its mid-generation change point is the 1994 facelift. Land Rover's workshop manual for the 300Tdi, Mpi and V8 Discovery states that it covers vehicles from the 1995 model year onwards, and the 300Tdi engine overhaul manual records the engine as fitted to the Discovery from 1995.
For 1995 to 1998 model years, the manual describes the standard 300Tdi as a 2.5 litre turbocharged, intercooled diesel with a Bosch rotary injection pump, a two-speed mechanical governor and a solenoid shut-off. There is no engine management ECU on that engine. Two variants sit alongside it in the same manual. One adds electronic exhaust gas recirculation (EGR), with a throttle position sensor on the pump feeding an EGR control unit. The other is electronic diesel control (EDC): a Bosch rotary pump with full electronic control of fuelling and timing, run by an engine control module in the driver's footwell on the A post, from sensors for engine speed, coolant, fuel and air temperature, boost pressure, airflow and throttle position. The manual's pump timing procedure covers a manual gearbox with EDC as well as automatic variants, so EDC is not confined to automatics in the manual's coverage. Before ordering fuel system parts, confirm which engine you have from the pump type and whether an engine control module is present.
The Discovery 1 has a separate chassis under its body, and in the Netherlands the APK inspection assesses both: the chassis frame and the load-bearing body must show no cracks and no corrosion that compromises their stiffness or strength. The RDW's APK handbook sets this out in Article 5.2.3 for passenger cars and Article 5.3.3 for light commercial vehicles; which one applies depends on how the vehicle is registered, and both use the same criterion. The inspector checks visually on a lift and, in case of doubt, with a round-headed hammer and by measurement. Workshop manual references in this section are to the 1995 to 1998 model year manual.
Damp carpet in the rear load space
Water in the rear load space can come from above or through the floor. Before the floor panel is condemned, check the sunroof drain tubes where a sunroof is fitted; the manual lists cleaning them as a service item.
Check: lift the carpet, then inspect the floor panel from underneath as well as from inside, looking for perforation and for earlier repairs; the APK handbook assesses a repair that was not welded or bolted to its standard as rust damage.
Remedy: the APK handbook accepts a repair with fitted sections welded in, or the part replaced, and sets the weld standard: chain welds covering at least 50 percent of the joint circumference, or plug welds of at least 4 mm diameter at no more than 20 mm spacing.
Difficulty: DIY for inspection; welding is a body shop job unless you have the equipment.
Sills, inner wings and bulkhead feet
The sills sit behind plastic trim. Lift the trim and tap the sill, the front inner wings and the bulkhead attachment points, and look at the rear wheelarches while you are there.
Remedy: repair sections welded in to the standard above.
Difficulty: DIY for inspection; repair panels need welding.
The manual for 1995 to 1998 model years lists ABS as an option. On a car that has it, the manual describes an inductive wheel speed sensor (the ABS sensor) at each wheel reading a 60-tooth exciter ring: at the front the ring is on the constant velocity joint inside the hub and the sensor sits in the top swivel pin; at the rear the ring is bolted to the brake disc bell. The parking brake is a transmission brake acting on a drum at the rear of the transfer gearbox, independent of the hydraulic circuits.
Why does the ABS warning lamp stay on?
Start with what is normal. Per the manual, the lamp is on during the self-check (1.3 to 2 seconds); if no fault is stored it goes out briefly, comes on again and then stays on until the vehicle is driven faster than 7 km/h. A lamp that is still on above that speed indicates a fault.
Check, in the manual's order: all exposed cables for damage or abrasion; the ABS earth; the battery state of charge; hub end float; all ABS fuses and electrical connections. The manual rechecks hub end float and sensor clearance together after bearing work, and its fault chart gives "high sensor air gaps" as a cause of the lamp, remedied by pushing the sensors in. Stored faults are read with Land Rover's Testbook diagnostic equipment; the system predates the EOBD standard. The manual also lists four causes for a lamp with no stored fault: a failure in the electrical supply, a bad ECU earth, a faulty warning light relay, or an ECU that is not connected.
Remedy: a sensor that has been removed for any reason goes back with a new sensor bush (and a new seal at the front). It is pushed through the bush until it touches the exciter ring and is knocked back to its running position when the vehicle is driven, and the manual's final step is to drive the vehicle and confirm the lamp goes out. After any wheel bearing replacement or adjustment, steering adjustment or brake disc replacement, the manual requires hub end float and sensor clearance to be rechecked. A damaged harness is replaced complete; the manual forbids unspecified cables or connectors on this system.
Difficulty: DIY with tools for the checks and the sensor refit; fault reading needs the diagnostic equipment.
Scraping noise from a front wheel
For a light scrape or squeak that follows wheel rotation at the front, one thing to look at is the brake disc shield, which the manual lists as a separate part from the mud shield. Look for distortion or corrosion bringing it into contact with the disc, and for debris trapped between shield and disc.
Difficulty: DIY with tools.
Transmission brake (handbrake) weak, or oil at the drum
Symptom: the handbrake does not hold on the third notch of the ratchet, or there is oil at the drum.
Adjustment: with a gear or P selected, the wheels chocked, the lever released and the console switch panel removed for access, the manual adjusts shoe wear at the drum adjuster from underneath the vehicle, turning it clockwise until the shoes are fully expanded against the drum and backing it off until the drum is free, then sets the cable thumbwheel below the lever so the brake is fully operational on the third notch, operates the brake to settle the shoes and rechecks the third notch. Cable adjustment is only for initial setting and cable stretch; it must not be used to take up shoe wear.
Oil at the drum: the drum sits on the transfer box rear output, and the rear output seal is the manual's listed leak point at that position. Before a short road test to confirm where the oil comes from, the manual checks the oil level and the plugs, has the breather pipe removed, inspected and refitted, and cleans the outside of the box. The repair for a leaking output seal is then to drain the transfer box, remove the output flange, inspect the seal track on the flange and renew the flange if it is damaged, discard the old seal, remove any sharp edges from the seal bore, fit a new seal and refill to the level plug.
Difficulty: adjustment DIY; seal renewal DIY with tools.
Failure Modes
300Tdi engine problems and fixes
Workshop manual references in this section are to Land Rover's manual for 1995 to 1998 model years and the 300Tdi engine overhaul manual. Cooling faults are not repeated here; they are covered in the Land Rover overheating diagnosis guide.
Engine will not pull to its normal top speed
Acceleration is normal up to a point, then the speed stops climbing. The injection pump is the costly suspect, so check the fuel supply before condemning it: the fuel lift pump, a mechanical camshaft-driven pump with a hand primer, specified at 42 to 55 kPa at 1800 rpm; the fuel pipework for air leaks; the fuel filter and its water separator; and on EDC-equipped engines the throttle position sensor, one of the engine control module's inputs. On EDC the manual notes that a failed sensor makes the module substitute a default value, which keeps the engine running but can cost it noticeable power.
Remedy: if the supply checks out, the injection pump is tested by a diesel injection specialist, who can advise whether repair is an option before a new pump is bought.
Difficulty: supply checks DIY with tools; pump work specialist.
Tapping from the top of the engine
Check: valve clearances. The manual specifies 0.20 mm cold for inlet and exhaust, set with feeler gauges in the overhaul manual's sequence (adjust number 1 with number 8 fully open, 3 with 6, 5 with 4, and so on).
Remedy: reset the clearances. If the noise remains, the rocker shaft, pushrods and tappets are the next things to inspect.
Difficulty: DIY with tools.
Blue smoke on a cold start
Blue-tinged smoke at start-up is a possible sign of oil passing worn valve guides or valve stem seals, or worn bores and rings, and the overhaul manual has checks for guides, stems and bores. Valve guide wear is measured as side movement of a new valve in the guide with the head 8.0 mm off its seat, maximum 0.15 mm; valve stems are measured at each end and the centre against the manual's diameters of 7.96 mm inlet and 7.94 mm exhaust, and worn stems are replaced.
Remedy: with the head off, the overhaul manual's checks on guides and stems apply, the stem seals are renewed on reassembly, and the bores can be inspected at the same time.
Difficulty: specialist, or experienced DIY with the overhaul manual and measuring tools.
Squeal from the front of the engine
On the 300Tdi a single serpentine belt with an automatic tensioner drives every ancillary except the air conditioning compressor, which has its own belt.
Illustrative image of an automatic belt tensioner: a cast arm and spring case carrying the pulley.
Check: the tensioner and belt. The manual's own indicator is the pair of cast lines on the tensioner arm and spring case: if they align, a new belt must be fitted. Beyond that, per Gates technical bulletin TT004-15, a squeal that a new belt does not cure can be caused by a failed pulley bearing or weak tensioner spring tension; a tensioner arm that chatters or bounces has already failed, and so has one that sticks or feels rough when rotated through its range with the engine off and cold.
Remedy: replace the tensioner if it fails those checks, then the belt. Clean the pulley grooves before the new belt goes on, and fit it exactly as the manual's routing shows; the manual has the water pump and viscous fan turning clockwise. The manual's schedule for normal highway use renews the belt at 160,000 km or eight years, whichever comes first, with inspection at every service and after every off-road session.
Difficulty: DIY with tools.
Timing belt renewal
The 300Tdi's camshaft and injection pump gears are driven by a 30 mm wide dry toothed belt, and renewing it, with the water pump, is the highest-priority service item on this engine. The manual's schedule sets a renewal interval for temperate climate operation and a shorter one for dusty atmospheres, high ambient temperatures and desert or tropical use, with a caution that a belt not renewed on time can fail and cause serious damage. During belt renewal the manual pins the injection pump gear with a timing tool. Timing kits for the 300Tdi are listed under Land Rover timing belts.
Difficulty: DIY with tools and the manual's timing pins; otherwise specialist.
Oily engine exterior
A crankcase breather hose runs between the air cleaner and the separator on this engine, and a split hose lets oil mist out onto the engine. Check the hose when the outside of the engine is persistently oily.
Difficulty: DIY.
Failure Modes
Driveline: hubs, propshaft and transfer box
Workshop manual references in this section are to the 1995 to 1998 model year manual.
Oil on the inside of a front tyre
The front axle has three separately lubricated spaces: the differential (oil), the swivel housings (oil as the manual specifies; later builds carry one-shot swivel grease) and the wheel bearings (grease), kept apart by the axle shaft seal and the inner and outer hub seals. Oil on the inner face of a front tyre can therefore come from the swivel housing seal or from the hub seals.
Check: the manual's leak diagnosis for this axle is to drain any housing with a high level and check the other levels; swivel oil is checked for grease leaking from the hub bearings, and hub grease should contain no oil; the axle breather is checked for blockage, because a blockage raises internal pressure and forces oil past the seals. The manual warns against assuming that a high level is overfilling or that a low level is an external leak.
Remedy: when the hub comes apart, fit new hub seals on reassembly (the manual discards the old seal), check the taper roller bearings, pack them with grease and set hub end float to the manual's figure with a new lock washer, tab bent over. Swivel housing seals and hub seals are listed under Land Rover axle and swivel parts.
Difficulty: DIY with tools.
Vibration from the rear
The manual's propeller shaft diagnosis is short: check that the universal joints and sliding splines are not seized or worn and that the shafts are correctly aligned; if both shafts are satisfactory and the vibration remains, check transfer box operation and road wheel balance. The rear shaft has a conventional universal joint at the gearbox end, a sliding joint sealed by a rubber gaiter, and an SGF rubber flexible coupling at the differential end, so the coupling is inspected as part of the shaft check. The coupling is a non-serviceable item with no grease nipple, removed only when it is to be replaced; the universal and sliding joints have grease nipples that are serviced at maintenance. The Land Rover driveshaft and propshaft problems guide covers universal joint and sliding joint wear in more depth.
Illustrative image of a rubber flexible coupling beside a propshaft joint, as fitted at the differential end of the rear shaft.
Remedy: if the coupling is found deteriorated, it is replaced with the shaft removed (scribe the flange alignment marks first). The manual's torques are 78 Nm for the coupling to the shaft, 47 Nm for the shaft at the transfer gearbox flange and 78 Nm for the three nuts and bolts at the axle flange, and the shaft goes back on its marks.
Difficulty: DIY with tools.
Failure Modes
Suspension
Workshop manual references in this section are to the 1995 to 1998 model year manual.
Clunk from the front at low speed on full lock
One of the first things to check is the Panhard rod, which locates the front axle sideways against the chassis. Check the torque of its fixings; the manual specifies 88 Nm for the rod to axle, the mounting arm to chassis and the rod to mounting bracket, and 110 Nm for the tie bar to Panhard rod. If the bolts are tight, check the end bushes for play.
Remedy: worn bushes are pressed out and in on the outer edge of the bush, never on the rubber inner. The manual's note on front suspension bushes is that when they are replaced, all bushes and fixings must be replaced. Panhard rod and radius arm bushes are listed under Land Rover suspension bushes.
Difficulty: torque check DIY; bush replacement needs a press or bush tool.
Diagnostic
Steering
Workshop manual references in this section are to the 1995 to 1998 model year manual's steering fault diagnosis and service schedule.
What causes steering shake at speed?
The manual's own statement is that vibration through the steering linkage strong enough to oscillate the steering wheel, with shimmy or wobble as its severe form, "is generally caused by out of balance road wheels", and it sets the checks in this order: tyres and wheel balance; the steering damper; the steering column universal joints; the steering linkage ball joints and the box; the front suspension rubbers and fixing torques, including radius arm bushes, Panhard rod and anti-roll bar; new radius arm bushes with new nuts, bolts and washers; on coil-sprung vehicles a damper kit if the problem persists; the steering box adjustment; hub end float; swivel resistance and condition; and finally a full geometry check. Swivel resistance comes near the end of that order, not the beginning. The Land Rover ball joint failure guide covers the linkage joint checks.
Swivel pin bearing preload is set by shims under the top swivel pin and checked by the manual's procedure, which differs between ABS and non-ABS vehicles (ABS cars have a different top pin and are set by torque to turn) and between model years. The check is made with the swivel housing oil seal and the axle shaft removed. Have the preload set to the manual's procedure. Difficulty: specialist, or experienced DIY with the manual.
Steering has become heavy
Check, in the manual's order: tyre type and pressures; the lower steering shaft universal joints for seizure and alignment; the steering box adjustment; then, with the drag link disconnected from the drop arm, whether the stiffness is in the column and box or in the axle, which points to the ball joints and the swivel lubrication and resistance.
If assistance is weak but the castor return is normal, the manual's chart runs: fluid level (fill and bleed), leaks, drive belt tension, then a pressure test at idle and at 1000 rpm, and where the pressure is low at every speed a bypass test to separate the box from the pump. The manual's own note is that insufficient pressure "is usually caused by low fluid level or PAS pump drive belt slip", with leaks, the relief valve, the box valve and worm, the box piston and worn pump or box components as the other causes. The pump is renewed when those tests point to it, not on assumption. Difficulty: checks DIY; pressure test and pump or box work specialist.
Power steering pipe chafing
The manual's service schedule checks for power steering fluid leaks and checks the hydraulic pipes and unions for chafing and corrosion. Where a pipe passes through a clip is worth a separate look: slackening the clip to see the pipe surface under it is not a manual step. Padding the clip is an owner precaution, not a factory specification. Difficulty: DIY.
Diagnostic
Instruments
Speedometer drops to zero intermittently
Where the vehicle has the electric speedometer, the manual for 1995 to 1998 model years places the speedometer transducer on the transfer box behind the transmission brake. Its connector is the first check. If the transducer itself is faulty, the manual's procedure is to disconnect the multiplug and remove one bolt. Difficulty: DIY.
Service Data
What oil and fluids does a Discovery 1 300Tdi take?
Values below are from Land Rover's workshop manual for 1995 to 1998 model years. Capacities are approximate and are a guide only; every level is checked by dipstick or level plug. The manual's lubricant chart selects the gear oil viscosity by ambient temperature.
Component
Specification
Viscosity
Capacity (approx.)
Engine sump, 300Tdi
RES.22.OL.PD-2, CCMC PD-2 or API CD
15W/40, the chart's only diesel grade, for ambient temperatures from minus 10 °C upwards
5.8 litres, plus 0.85 litres when a new filter is fitted
Manual gearbox
ATF Dexron IID
All temperatures
2.67 litres
Automatic gearbox
ATF Dexron IID
All temperatures
9.1 litres
LT230T transfer gearbox
API GL4 or GL5, MIL-L-2105 or MIL-L-2105B, C or D
90 EP from minus 10 °C upwards; 80 EP up to 30 °C
2.30 litres
Front and rear differentials
API GL5, MIL-L-2105 or MIL-L-2105B, C or D
90 EP from minus 10 °C upwards; 80 EP up to 30 °C
1.70 litres each
Swivel pin housings
As the differentials, on vehicles with oil-filled swivel housings; later builds have one-shot swivel grease instead, so check which your housing carries before topping up
As the differentials
0.35 litres each (oil-filled housings)
Power steering
ATF Dexron IID
All temperatures
2.90 litres LHD, 3.40 litres RHD (box and reservoir)
Cooling system, 300Tdi
Ethylene glycol anti-freeze with non-phosphate corrosion inhibitors, one part to one part water
Never below 25 percent anti-freeze, never above 60 percent
11.5 litres
Brake and clutch fluid
DOT 4, minimum boiling point 260 °C
As required
As required
Fuel tank
Diesel
As required
89 litres usable
Next Steps
Which Discovery 1 300Tdi upgrades and precautions are worth doing?
None of these changes the car's specification; each one follows from a check above, and the manual references are to the 1995 to 1998 model year manual.
Timing belt kit with the water pump, on the manual's schedule.
A new serpentine belt when the tensioner's cast lines align, and a new tensioner when its arm chatters or bounces, or sticks or feels rough when rotated by hand.
Tapping the sills, floor and inner wings before the APK, where doubt about corrosion is resolved with a hammer and measurement.
A breather hose check when the engine exterior stays oily.
Pipe clip padding on the power steering pipes, as an owner precaution against chafing.
On ABS cars, a new sensor bush (and seal at the front) every time a wheel speed sensor is removed, and hub end float and sensor clearance rechecked after bearing, steering or disc work.
Next Steps
Where do you find the correct workshop information?
The 300Tdi Discovery is documented in Land Rover's own workshop manual for the 1995 model year onwards, which also covers the Mpi and V8 cars, and in the 300Tdi engine overhaul manual. Licensed reprints of the workshop manual are published by Brooklands Books, and current official Land Rover technical information comes through a main dealer or a licensed technical data subscription. The Land Rover manuals guide explains which publication answers which question. For a 1995 to 1998 Discovery the manual is the source for the full procedures and schedules, including the swivel pin bearing preload procedure and the timing belt renewal interval for your use.
Next Steps
Related guides
Discovery 1 200Tdi
Faults, fixes and upgrades for the Discovery 1 200Tdi.
Which Discovery 1 model years have the 300Tdi engine?
Land Rover's workshop manual for the 300Tdi, Mpi and V8 Discovery covers vehicles from the 1995 model year onwards, and the 300Tdi engine overhaul manual records the engine as fitted to the Discovery from 1995. The Discovery 1 ended in 1998, so the 300Tdi Discovery is a 1995 to 1998 model year car as that manual covers it. The 200Tdi Discovery 1 has its own guide.
Does the Discovery 1 300Tdi have an engine ECU?
The standard 300Tdi has mechanical injection with no engine management ECU; the 1995 to 1998 model year workshop manual lists a Bosch rotary pump with a mechanical two-speed governor. Variants with electronic diesel control (EDC) do have an engine control module, which the manual documents on manual gearbox vehicles as well as automatics. Diagnosis on an EDC engine is through that module, not through a generic EOBD scanner.
Why does the ABS light stay on after I start a Discovery 1?
It is designed to. The manual for 1995 to 1998 model years describes the lamp on through the self-check, out briefly if no fault is stored, then on again until the vehicle is driven faster than 7 km/h. If it is still on above that speed it indicates a fault: the first checks are the exposed cables, the ABS earth, the battery, hub end float and the fuses and connections, the stored faults are read with Land Rover's Testbook equipment, and the manual's remedy for high sensor air gaps is to push the sensors fully home.
What are the valve clearances on a 300Tdi?
0.20 mm cold, inlet and exhaust, from Land Rover's workshop manual for the 1995 to 1998 model year Discovery; the 300Tdi engine overhaul manual sets them with feeler gauges with the opposite valve fully open in its sequence.
What are the oil, coolant and fuel capacities of a Discovery 1 300Tdi?
From Land Rover's workshop manual for 1995 to 1998 model years, as approximate figures to be confirmed at the dipstick or level plug: engine sump 5.8 litres plus 0.85 litres with a new filter (15W/40); manual gearbox 2.67 litres of ATF Dexron IID; transfer box 2.30 litres of 90 EP (80 EP in colder climates per the manual's chart); each differential 1.70 litres and each oil-filled swivel housing 0.35 litres of the same grade; cooling system 11.5 litres of a one-to-one anti-freeze and water mix; fuel tank 89 litres usable.
What is the Panhard rod bolt torque on a Discovery 1?
88 Nm for the rod to axle, the mounting arm to chassis and the rod to mounting bracket, and 110 Nm for the tie bar to Panhard rod, from the workshop manual for 1995 to 1998 model years. A low-speed clunk on full lock is checked at these bolts and then at the bushes.
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