The Mitsubishi 4M40 2.8TD engine is one of the most respected diesels Mitsubishi ever bolted into a Pajero. Fitted to the second-generation Pajero (and a handful of late first-gen models) through the 1990s and into the early 2000s, the Pajero 2.8TD engine earned a reputation in South Africa for soldiering on past 400,000 km when it is looked after. It is mechanically honest, well-suited to our fuel and our heat, and refreshingly simple to live with.
This guide breaks down how the 4M40 is built, why it lasts, the faults that do crop up with age, and which upgrades are sensible rather than reckless. If you are weighing up an older Pajero, read it alongside our wider Pajero Technical Guides so you go in with eyes open.
4M40 vs 4M41: clearing up the engine codes
Before anything else, get the codes straight, because second-hand listings in South Africa muddle them constantly. The 4M40 is the 2.8-litre turbo-diesel (2,835 cc). The later 4M41 is the 3.2-litre Di-D common-rail unit fitted to the third-generation NM/NP Pajero. They are different engines from different eras: if a seller calls a 2.8 a “3.2”, or a 3.2 a “2.8”, treat the rest of the advert with suspicion. This article is strictly about the 4M40 2.8TD.
| Specification | 4M40 (2.8TD) |
|---|---|
| Configuration | Inline-4, SOHC 8-valve |
| Displacement | 2,835 cc |
| Bore × stroke | 95.0 mm × 100.0 mm |
| Induction | Turbocharged, intercooled (most SA models) |
| Fuelling | Indirect injection, mechanical rotary injector pump |
| Timing drive | Timing chain (not a belt) |
| Power (typical) | Approx. 92–103 kW depending on spec and year |
| Torque (typical) | Approx. 290–314 Nm, low in the rev range |
Design: why the timing chain matters
The single most important thing to know about the 4M40 is that it uses a timing chain, not a timing belt. This is a genuine ownership advantage. There is no fixed-interval belt replacement looming over you every 90,000–100,000 km, and no catastrophic interference failure if a belt skips or snaps. The chain is designed to last the life of the engine when oil changes are kept up, because the chain and its tensioner rely on clean engine oil to stay quiet and correctly tensioned.
That said, “lasts the life of the engine” assumes the engine has been serviced properly. A 4M40 run on dirty or over-extended oil can suffer a stretched chain and a worn tensioner, which shows up as a rattle on cold start-up. It is not common, but it is the price of neglect. The cast-iron block and SOHC 8-valve head are deliberately low-stress: modest power per litre, big bearings, and plenty of cooling margin. That conservative design is exactly why these engines tolerate heat, dust and long highway runs so well.
The injector pump and fuelling
The 4M40 runs an indirect-injection (IDI) combustion chamber fed by a mechanical rotary injector pump. There is no temperamental high-pressure common-rail system, no expensive piezo injectors and no DPF to clog. This makes the 2.8TD remarkably tolerant of variable diesel quality, which matters on long trips through rural South Africa and across borders. The trade-off is that IDI engines are a little less efficient and noisier than modern common-rail units, and they need their glow plugs in good order for clean cold starts.
The injector pump itself is durable but not immortal. Worn pump seals or a tired lift pump cause hard starting, low power and visible smoke. A pump in good condition, with clean fuel and serviced injectors, is the heart of a sweet-running 4M40.
Common faults to check on a high-mileage 4M40
No 30-year-old engine is faultless. The good news is that the 4M40’s weak points are well documented and mostly age- and maintenance-related rather than design flaws. Watch for these:
- Cold-start chain rattle — a brief metallic rattle at start-up can mean a worn timing chain tensioner, usually from poor oil maintenance.
- Cracked No.4 cylinder / overheating damage — like many IDI diesels, a 4M40 that has been badly overheated can crack around the rear cylinder. Check service history and look hard for any history of overheating.
- Worn injector pump seals — diesel weeping from the pump, hard hot starts and smoke point here.
- Tired glow plugs and relay — rough, smoky cold starts on a winter Highveld morning.
- Turbo and intercooler oil residue — some oil misting is normal with age; heavy oil in the intercooler piping suggests a worn turbo.
- Radiator and cooling system fatigue — the engine is tough, but it must be kept cool. Aging radiators, viscous fans and water pumps are the usual culprits behind overheating.
None of these are deal-breakers in isolation, but they shape what you should pay. For a structured walk-around before you buy, follow our Used Pajero Buying Guide: The 20-Point Inspection, and cross-reference the engine notes in Pajero Common Problems by Generation so you know what is normal wear and what is a red flag.
Buy the maintenance history, not the mileage. A 380,000 km 4M40 with a folder of receipts is a safer bet than a 180,000 km example with no paperwork.
Sensible upgrades (and what to avoid)
The 4M40 responds well to gentle improvement, but it is a low-stress engine and you should respect that. Chasing big power numbers shortens its life. Sensible, reliability-friendly upgrades include:
- Cooling upgrades first — a new or uprated radiator, fresh coolant and a healthy viscous fan do more for longevity in SA conditions than any power mod.
- Free-flowing (but quality) air filtration and a snorkel — useful for dust and water crossings, provided the airbox stays properly sealed.
- A mild, well-set-up intercooler and a modest boost increase — done conservatively, this improves driveability without over-stressing the bottom end.
- Fresh injectors and a serviced pump — restoring the fuelling system to spec is the single best “upgrade” most 4M40s need.
- Quality engine oil on a shorter interval — this is what keeps the timing chain quiet and the bearings happy.
What to avoid: aggressive fuel-pump tuning that pours in diesel for smoke-and-noise “power”, oversized turbos the cooling system cannot keep up with, and deleting safety margins. The 4M40 rewards restraint. Remember too that the engine is only half the drivetrain story — the way a Pajero puts that torque down is governed by its transfer case, which we cover in our Super Select 4WD Explained guide.
Longevity: how to reach 400,000 km
Owners regularly take the Pajero 2.8TD engine well past 350,000–400,000 km, and the recipe is unglamorous. Change the oil and filter on time with a good-quality lubricant; keep the cooling system in top condition and never ignore a rising temperature gauge; use clean diesel and replace fuel filters religiously; and address small issues — a weeping seal, a tired glow plug, a slightly noisy turbo — before they cascade. Treated this way, the 4M40 is one of the great long-distance overlanding diesels and a sound foundation for an older, affordable Pajero.
Frequently Asked Questions
Does the Pajero 2.8TD (4M40) have a timing belt or a timing chain?
Is the 4M40 the same as the 4M41?
How many kilometres will a 2.8TD Pajero last?
What is the most common 4M40 problem to watch for?
Are power upgrades safe on a 2.8TD?
For more on running and maintaining your truck, browse the full Pajero Technical Guides hub, and swap notes with other owners over on the SA Pajero Community.