Mitsubishi 4D56 engine: known problems

Used in 4 guides · 2.5L diesel · 11 known problems

Displacement

2.5L

Fuel

diesel

Known problems11

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

Balance-shaft belt failure (separate from timing belt)

The 4D56 uses a separate balance-shaft belt as well as the main timing belt. The balance-shaft belt can degrade and fail well before the timing belt; if it shreds it can foul the timing belt and cause severe vibration or engine damage.

Fix: Replace BOTH the timing belt and balance-shaft belt together (with tensioners and water pump) at ~100,000km - do not assume one covers the other.

Often under 100k km · ~$600-1500

Listed for: Mitsubishi Challenger PA / PB-PC · Mitsubishi Triton ME / MF / MG / MH / MJ

High

4D56 timing belt failure

Timing belt MUST be replaced at 100k. Failure = bent valves on the 4D56.

Fix: Replace on schedule with belt kit. Non-negotiable maintenance item.

From 100k km interval · ~$3000+ (if snaps)

Listed for: Mitsubishi Triton MK · Mitsubishi Triton ML / MN

High

Cylinder-head / coolant-loss overheating (campaign 020116)

A factory machining issue on 2.5L 4D56HP engines built before 18 March 2014 causes 'repetitive coolant evaporation' and coolant loss under high load (e.g. towing), leading to overheating and head/head-gasket damage. Mitsubishi ran preventative service campaign 020116 (Nov 2014) to address it.

Fix: Confirm the 020116 campaign work was carried out; keep cooling system fresh, watch coolant level closely, and avoid sustained high-load running until verified. Repair head/gasket if already damaged.

Any · ~$2500-6000

Listed for: Mitsubishi Challenger PA / PB-PC

High

Timing belt snap (interference engine)

100,000km / 5-year belt interval is MANDATORY. Belt failure = bent valves = top-end rebuild. Confirm service history at pre-purchase or budget for the belt job.

Fix: Replace timing belt, balance shaft belt, tensioners, idlers, and water pump as a single job.

From 100k+ km if neglected · ~$2000-4000

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

High

4D56 engine overheating (recall)

Mitsubishi issued service campaign 020116 in 2014 for 4D56HP engines. Repetitive coolant evaporation under heavy load (especially towing) plus poor head gasket sealing caused overheating.

Fix: Updated radiator cap (127 kPa), 50% coolant concentration, new ECU programming, smoother cylinder block surface from March 2014 production. Verify recall completed.

Pre-2014 · Recall fix

Listed for: Mitsubishi Triton ML / MN

Medium

Suction control valve (SCV) / injector faults

A failing common-rail suction control valve or worn injectors cause surging, hard starting, black smoke and loss of power; injectors can also seize in the head making removal difficult.

Fix: Replace the SCV; have injectors tested and replaced by a diesel specialist; use quality fuel and a good secondary filter.

From 120k+ km · ~$300-2500

Listed for: Mitsubishi Challenger PA / PB-PC

Medium

EGR / intake soot build-up and cracked intercooler

Carbon builds up in the intake/EGR and the intercooler or boost pipes can crack or leak, causing reduced power, poor economy and limp mode.

Fix: Clean the intake/EGR, pressure-test the intercooler and boost piping, and replace cracked components.

From 100k+ km · ~$300-1200

Listed for: Mitsubishi Challenger PA / PB-PC

Medium

Automatic transmission overheating on tow/off-road

The 5-speed auto is poorly suited to sustained heavy towing in hilly terrain and off-road crawling - it overheats and drops into limp mode, and neglected fluid shortens its life.

Fix: Service the transmission every ~40,000km, fit a transmission cooler for towing, and avoid towing near the 3000kg limit over long hilly runs.

Any · ~$300-3000

Listed for: Mitsubishi Challenger PA / PB-PC

Medium

Heavy crankcase blow-by

High-km 4D56s develop heavy blow-by - oil mist out of the breather, oil consumption, oil leaks at every gasket. Symptom of ring/bore wear.

Fix: Bottom-end rebuild required to properly address. Many owners just keep topping up oil and live with it.

From 200k+ km · ~$1500-3500

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

Medium

Body and chassis rust

Rust on rear wheel arches, chassis rails.