Parts for your 1989 Mitsubishi Pajero-Spark plugs

1989 Mitsubishi Pajero spark plugs — are they relevant?

Yes — if the 1989 Mitsubishi Pajero is a petrol model, it absolutely uses spark plugs. Technical sources such as the Mitsubishi Pajero/Montero L040 Series Workshop Manual (1983–1991) specify conventional spark plugs for the 2.6L 4G54 four-cylinder and the 3.0L 6G72 V6 petrol engines. In contrast, the 2.5L 4D56 turbo-diesel uses glow plugs, not spark plugs. Parts catalogues from NGK and Denso for AU/NZ vehicles back this up by listing specific spark plug part numbers for the petrol engines and glow plugs for the diesel. The under‑bonnet tune label on many local vehicles also lists the plug gap for petrol variants.

For owners of petrol 1989 Pajeros, spark plugs do the critical job of igniting the air–fuel mix in each cylinder so the engine starts cleanly, idles smoothly, and pulls well up hills without chewing through extra fuel. Fresh, correctly gapped plugs help with cold starts on frosty mornings, reduce misfires on corrugations, and keep emissions tidy. On these older Mitsi engines, keeping the spark system in good nick makes a noticeable difference to drivability.

Replacement intervals depend on plug type and how the vehicle’s used. As a guide, standard copper plugs are often changed around 20,000–30,000 kilometres, while platinum or iridium types can stretch much further (often 80,000–100,000 kilometres). Always follow the vehicle’s service schedule and the plug maker’s guidance. The correct heat range and gap are crucial, check the workshop manual or the under‑bonnet label. Typical plug gaps for these engines sit roughly in the 0.8–1.1 mm range, depending on engine and plug design.

• Do one cylinder at a time and number the leads to avoid mix‑ups (distributor engines).
• Blow debris from plug wells before removal, work on a cool engine.
• Check and set the gap with a feeler gauge if the plug isn’t pre‑gapped.
• Thread new plugs in by hand first to avoid cross‑threading, then torque to the plug maker’s spec (don’t rely on “feel” with alloy heads). Most modern plugs are nickel‑plated — avoid anti‑seize unless explicitly specified.
• Inspect leads and the distributor cap/rotor at the same time, replace perished parts.
• If there’s oil in the plug tubes, sort the rocker cover/tube seals before refitting.

Running a diesel 1989 Pajero? There are no spark plugs on that engine. Diesels ignite fuel by compression heat and rely on glow plugs only for cold starts, as noted in the factory service manual and diesel system guides.

Which engines in a 1989 Pajero use spark plugs?

The 2.6L 4G54 and 3.0L 6G72 petrol engines use spark plugs (four and six respectively). Diesel variants such as the 2.5L 4D56 turbo‑diesel use glow plugs instead. This split is detailed in the Mitsubishi workshop manual and supported by AU/NZ parts catalogues from NGK and Denso.

How often should spark plugs be replaced on a 1989 Pajero petrol?

As a general rule: copper around 20,000–30,000 km, iridium/platinum much longer (often 80,000–100,000 km). Factor in heavy towing, dusty tracks, or lots of short trips, which can justify earlier changes. Always go by the service schedule and plug manufacturer’s advice.

What spark plug gap and type should be used?

Use the heat range and design specified for the exact engine code (4G54 or 6G72) in the workshop manual or local parts catalogue, and check the under‑bonnet label for gap guidance. Many petrol Pajeros of this era specify gaps around 0.8–1.1 mm. If buying pre‑gapped plugs, still confirm the gap before installation.