Engine options
All the original engines are simple to maintain and service, and they’re all good, solid reliable units, given proper servicing and use. If the engine (or any other major component) has been rebuilt, scrutinise the receipts because build quality and extent varied widely.
The 4- and 8-cylinder petrol engines and the early 2.25-litre diesels all had timing chains (on four cylinder engines a tinny rattle from the front cover suggests a worn chain and/or tensioner issue), but the 2.5-litre naturally aspirated and turbo diesels used cam belts, so check the belts have been replaced at the stipulated interval of 60,000 miles for normal use.
Many of these vehicles have received replacement engines and gearboxes over the years, mainly 200 and 300Tdi diesels, but also V8s including carburettor and EFI fuel injected versions. So confirm which engine is fitted and, if a later V8 or Tdi is installed, use the tips in our Discovery 1 Buying Guide technical supplement (LRM April 2021).
4-CYLINDER PETROL ENGINES
The 2.25- and 2.5-litre petrol engines are very similar: both surprisingly smooth running and reliable, though delivering only around 20-22 mpg. A healthy petrol engine should accelerate easily with gentle throttle application. If not, or the idle speed is unsteady, the carburettor may be worn or incorrectly set (assuming the ignition timing is correct).
4-CYLINDER DIESEL ENGINES
Expect around 26 mpg from these inherently noisy diesels. The naturally aspirated 2.25- and 2.5-litre engines are relatively bullet proof, but 19J turbocharged versions developed bottom end problems back in the day, earning a reputation for catastrophic failure. Later turbo engines had a strengthened bottom end and became reliable. They are rare now because, even those that didn’t fail were often replaced by later Tdi engines. Any now remaining are likely to be in good order and quite desirable, given their rarity and the extra torque they produce. The turbocharger is a basic trouble-free unit but, like any turbo, the shaft bearings wear (especially if engine oil changes have been ignored) producing a high-pitched sound of varying intensity.
A relatively slow but regular tapping from a diesel may be caused by a loose hot-plug (pre-combustion chamber). These are pressed into the underside of the head and can work loose, causing a tapping sound when the relevant piston rises. The head needs to come off to replace them.
The 2.25 diesel is a five main bearings engine and was known as the 2.3 when fitted in the Series III to distinguish it from the SIII’S earlier three bearing engine, though capacity remained the same.
THE V8 PETROL
The twin carburetter 3.5-litre Rover V8 will give smooth running, but at a cost of 16 to 20mpg. The V8 doesn’t make it a road burner, but it’s the quickest of the bunch. It’s also rare and worth having for the sake of itself. It’s a good solid and reliable engine and, given proper servicing which includes regular oil and filter changes with quality products, it lasts well. Without this, expect a worn camshaft and associated valve train components which will be noisy and tappety, even knocking at the top end in extreme cases. LPG conversions give the V8 models diesel-type fuel costs, and originality is not a concern here because the LPG system can easily be removed. But it’s important to know the LPG system has been properly installed, maintained and checked, so expect to see paperwork confirming this.