Parts for your 1999 Mitsubishi Pajero-Drive belt tensioner

1999 Mitsubishi Pajero drive-belt tensioner: what’s fitted and how to look after it

Based on technical references including the Mitsubishi Pajero/Montero Workshop Manual (1997–2000), Gregory’s Pajero 1991–1999 manual, and the Gates Accessory Belt Drive System catalogue for the period, the 1999 Mitsubishi Pajero may or may not use an automatic accessory drive-belt tensioner, depending on the engine. The 3.5‑litre V6 petrol (6G74) is shown with a spring‑loaded drive-belt tensioner assembly in the factory manual, while the 2.8‑litre turbo‑diesel (4M40) uses separate V‑belts that are tensioned manually via the alternator, power‑steering pump and an A/C idler. So, a “drive-belt tensioner” is relevant to V6 petrol models, it isn’t used on the 2.8 diesel because that setup relies on manual adjusters rather than a self‑tensioning pulley.

For V6 petrol models where a drive-belt tensioner is fitted, the part’s job is to keep the serpentine belt at the right tension as revs and temperatures change. Under the bonnet, the spring‑loaded arm and pulley take up slack so the alternator, power steering and A/C keep humming along without slip. A healthy tensioner cuts belt noise, prevents glazing, and helps the belt last its full service life.

As part of regular servicing, it’s smart to inspect the drive-belt tensioner every 15,000–20,000 kilometres. With the engine off, check that the pulley spins smoothly with no roughness, wobble or play. Watch the arm at idle, it should sit steady without excessive flutter. Any chirps on cold start, squeals when turning the steering, or visible belt fraying are cues to take action.

Replacement is usually straightforward for a competent DIYer, but a shop can knock it over quickly too. Typical steps include relieving belt tension with a spanner on the tensioner boss, slipping the belt off, unbolting the old unit, then fitting the new tensioner and re‑routing the belt to the workshop diagram under the bonnet. Always spin up any idler pulleys while you’re in there and replace the belt if it’s cracked, glazed or over the time/kilometre limit.

Good practice is to replace the tensioner with every second belt, or around 90,000–120,000 kilometres (or 7–10 years), sooner if there’s noise, oil contamination or pulley wear. Use quality parts, check pulley alignment, and avoid levering against delicate castings. For 4M40 diesel owners without an automatic tensioner, correct belt deflection is set with the adjuster bolts on the alternator, A/C and power‑steering brackets as outlined in the factory manual.

• Common symptoms of a crook tensioner: belt squeal, chirp on start‑up, visible belt flutter, wobbling pulley, or charging/overheating warnings.
• Benefits of timely replacement: quieter running, better accessory performance, less risk of a tossed belt out bush.

Popular questions

How can someone tell if their 1999 Pajero actually has an automatic drive-belt tensioner?

Pop the bonnet and look at the front of the engine. V6 petrol models generally have a spring‑loaded arm with a smooth pulley pressing on the serpentine belt. The 2.8 diesel typically runs multiple V‑belts with slide‑type adjusters on the alternator, A/C and power steering, and no spring‑loaded arm. The engine code on the build plate helps: 6G74 (V6) usually has it, 4M40 (diesel) doesn’t.

How often should a Pajero drive-belt tensioner be replaced?

On V6 models with a tensioner, many workshops replace it with every second belt, roughly 90,000–120,000 kilometres or 7–10 years. Replace sooner if the pulley’s noisy, the arm jitters, or the belt shows glazing or uneven wear. If heading on a long trip or towing regularly, proactive replacement can save headaches.

Is it safe to drive with a noisy or weak tensioner?

It’s risky. A failing tensioner can let the belt slip or jump off, which can knock out the alternator, power steering and A/C, and on some setups affect coolant circulation. Short, gentle trips might get by, but it’s best to sort it promptly before it strands anyone.