Parts for your 2004 Mitsubishi Pajero-Drive belt tensioner

2004 Mitsubishi Pajero drive belt tensioner — what it does and how to look after it

Yes, a drive belt tensioner is fitted to the 2004 Mitsubishi Pajero. According to the Mitsubishi Motors Pajero/Montero NM–NP Workshop Manual (Group 14 – Engine) and major parts catalogues from Gates and Dayco for the 2004 model year, both the 3.8L 6G75 petrol and the 3.2L 4M41 diesel use an automatic accessory drive belt tensioner. Diesel variants also run a separate A/C belt with its own adjuster, but the main accessory belt still relies on a spring‑loaded tensioner.

On this Pajero, the drive belt tensioner keeps the serpentine belt at the sweet spot for tension, so the alternator, power steering pump, water pump and A/C compressor all play nicely under load. It constantly takes up slack as the belt wears and stretches, and its internal damping smooths out belt flutter and pulley vibrations that cause squeaks and premature wear.

For regular servicing, it pays to give the tensioner a proper once‑over every service or 15,000 km. Quick tells of a tired unit include belt squeal on cold start, chirping as revs change, a fluttering tensioner arm, a wobbling or gritty pulley bearing, or a belt that looks glazed, cracked or is wearing on one edge. Electrical warnings, heavier steering, rising temps or weak A/C can also trace back to a slipping belt from a lazy tensioner.

When replacement time comes, treat the tensioner as a matched pair with the belt. If the belt’s done a hard life or clocked a big number, throw a fresh belt on with the new tensioner, and consider renewing any idler pulleys while you’re there. Use the correct square drive or hex to relieve tension, don’t pry against alloy covers. Route the belt exactly as per the under‑bonnet diagram or workshop manual, torque fasteners to spec, then run the engine and watch the belt track quietly without wandering.

There’s no fixed expiry date, but many Pajero tensioners comfortably reach 100,000–150,000 km. Dust, heat, mud and water crossings can shorten that. Never try to “tighten” the main automatic tensioner—if it’s weak or noisy, replacement is the fix. Avoid belt dressings, they mask the problem and can contaminate the pulley. Sticking to quality belts and OE‑quality tensioners keeps the big wagon dependable on the school run and the weekend track alike.

• Inspect at each service: belt condition, pulley noise/play, tensioner arm movement and alignment.
• Replace the belt and tensioner together if there’s noise, misalignment, limited travel or repeated belt wear.
• On 4M41 diesels, remember the separate A/C belt has its own adjuster—check and set that correctly too.

Popular questions about 2004 Mitsubishi Pajero drive belt tensioner

Does the 2004 Pajero have a drive belt tensioner or is it manually adjusted?

It has an automatic (spring‑loaded) tensioner for the main accessory belt on both 3.8L petrol and 3.2L diesel engines. The factory workshop manual and Gates/Dayco catalogues list dedicated tensioner assemblies for these engines. Some diesels also have a separate A/C belt with a manual adjuster, but that’s in addition to the main automatic tensioner.

How often should the tensioner be replaced?

There’s no set interval. Inspect it at each service and replace on condition—noise, rough pulley bearing, weak spring, misalignment or repeated belt wear are the triggers. Many last 100,000–150,000 km, but harsh conditions (dust, mud, heat) can bring that forward. It’s smart to fit a new belt whenever you replace the tensioner.

Can the Pajero’s tensioner be tightened to stop belt squeal?

No. The main unit is self‑adjusting, it can’t be “tightened”. If it’s squealing due to a weak spring or failing damper/bearing, replacement is the cure. On 4M41 diesels, only the separate A/C belt has a manual adjustment—set that correctly, but don’t try to preload the automatic main tensioner.