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Mitsubishi 4G54 engine: known problems

Used in 2 guides · 2555cc petrol · 6 known problems

Displacement

2555cc

Layout

I4 NA

Fuel

petrol

Known problems6

Everything our guides list for the variants with this engine: the engine itself plus the gearbox and ancillaries it's paired with. Each shows which cars it's listed for.

High

Timing belt failure (interference engine)

The 4G54 is belt-driven and an interference design - an overdue or perished belt that snaps will bend valves and wreck the top end. On 30-40 year old cars history is often unknown.

Fix: Replace the timing belt, tensioner and balance-shaft belt on schedule (~100,000km / by age); confirm when it was last done before buying.

Any overdue belt · ~$300-700 service / $2000+ if it snaps

Listed for: Mitsubishi Pajero NA-NG / NH-NL

Medium

Worn jet-valve / valve guides and oil burning

High-km Astron heads wear valve guides and the small jet valves, leading to oil burning, smoke on start-up and lost compression.

Fix: Head recondition - valve guides, seals and jet-valve service by a specialist.

From 200k+ km · ~$1000-2500

Listed for: Mitsubishi Pajero NA-NG / NH-NL

Medium

Timing belt service neglect

100,000km / 5-year belt interval. The 4G54 also has a balance shaft chain that wears - tensioner failure causes heavy rattle.

Fix: Replace timing belt and tensioners. Inspect balance chain at the same time - replace if worn.

From 100k+ km if neglected · ~$600-1200

Listed for: Mitsubishi Triton ME / MF / MG / MH / MJ

Low

Carburettor / EFI tuning and tired ancillaries

Carby versions drift out of tune; early EFI sensors, vacuum lines and ignition components are all decades old now.

Fix: Tune-up, replace perished vacuum/fuel lines and ageing ignition parts; budget a consumables refresh.

Any (age) · Varies

Listed for: Mitsubishi Pajero NA-NG / NH-NL

Low

Carburettor wear and flooding

Early carby setups suffer worn needles and seats, heavy floats, hardened vacuum lines. Symptoms: uneven idle, poor cold start, flooding.

Fix: Rebuild the carby with a kit, or replace. Reset base mixtures after.

From 120k+ km · ~$300-600

Listed for: Mitsubishi Triton ME / MF / MG / MH / MJ

Low

Jet valve issues

Astron MCA-Jet design uses a small auxiliary jet valve per cylinder. Valves can stick or burn over time, causing rough running.

Fix: Jet valve replacement at major service. Some owners delete and run plugs.

From 150k+ km · ~$300-500 DIY

Listed for: Mitsubishi Triton ME / MF / MG / MH / MJ

Cars with the 4G542

Mitsubishi Pajero NA-NG / NH-NL (1st-2nd gen)

1983-2000 · 2.6L 4G54 petrol (1st gen)

Value

Mitsubishi Triton ME / MF / MG / MH / MJ

1986-1996 · 2.6L 4G54 petrol I4

Caution

From the FlamingCars guides for these cars. Specs are shown only where the guides agree and the value is verified.