A "wet belt", Ford calls it a belt-in-oil system, is a timing belt that runs inside the engine, submerged in the same oil that lubricates everything else, instead of sitting dry on the outside of the block like a conventional timing belt. Ford introduced it on the 2.0-litre EcoBlue diesel to cut friction, noise, and a bit of weight compared with a timing chain.

In practice, it hasn't worked out as cleanly as intended. Running a rubber-and-fabric belt in oil means belt material can shed into the oil circuit over time, and on affected Rangers that's shown up as blocked oil pickups, starved oil pressure, and, in the worst cases, a belt failure that lets the pistons contact the valves.

It's also not purely a mileage story. Frequent short trips mean more DPF regeneration cycles, and each regen cycle puts a small amount of extra diesel into the engine oil to burn off soot. That diluted oil is exactly what the wet belt sits in, so a Ranger doing lots of short local runs can be at real risk well before a similar Ranger doing steady highway kilometres, regardless of what the odometer says.

Catch these early and a wet belt replacement is a straightforward, planned job.

• A rattle, tick, or whine from the front of the engine, especially cold on startup often the first sign the belt or its tensioner is wearing.

• Black flecks or a gritty texture in the oil on the dipstick or at an oil change, belt material shedding into the oil.

• The check engine light, particularly alongside rough idling or a slight power loss.

• Rough running or misfiring that wasn't there before.

• Difficulty starting, or the engine cranking longer than normal.

Any one of these on its own is worth a check. More than one together means don't wait.

The 2.0 litre EcoBlue is an interference engine, which means the pistons and valves occupy the same space at different points in the rotation, the timing belt is what keeps them apart. If the belt lets go or jumps time, there's nothing stopping contact between them.

The practical range of mostly bad outcomes. 

• Bent valves and damaged pistons, requiring a cylinder head rebuild

• Debris from a shredding belt blocking the oil pickup, starving the engine of oil pressure and damaging bearings and the crankshaft

• In the worst cases, a written-off engine a new or reconditioned 2.0 litre EcoBlue isn't a cheap fix

This is the gap between a $3000 preventative job and a $25K engine replacement  and it's entirely avoidable with a timely check.

Ford's official interval for the 2.0-litre EcoBlue wet belt is 150,000km or 10 years, whichever comes first. That's the figure on the factory service schedule, and it's a reasonable one if the belt performs as designed. 

In practice, workshops across NZ and Australia are seeing wet belts show wear, oil contamination, or early tensioner problems well before that mark, commonly somewhere in the 80,000–100,000km range, particularly on Rangers used for towing, heavy loads, commercial/fleet duty, or a lot of short trips.

Our recommendation: treat 150,000km/10 years as the outer limit, not the target. If your Ranger is past 80,000km on its original wet belt, or you're not sure it's ever been done, it's worth a proper inspection oil condition, tensioner play, belt material even if nothing's showing up yet. That inspection is cheap. An engine rebuild isn't.

This isn't a simple external belt swap. Because the belt runs inside the engine, replacing it properly means removing the sump, draining the oil, replacing both internal belts (the timing belt and the belt that drives the oil pump), cleaning any shed belt material out of the oil system, and refitting with new seals and fresh oil. Doing one belt and leaving the other is a false economy the labour overlap means it makes sense to do both while everything's already apart.

There's also a genuine cost difference between 2WD and 4WD Rangers, purely down to labour 4WD models take longer because of access and drivetrain layout.

A properly done preventative wet belt job sump off, both belts, new seals, fresh oil and water pump, commonly runs in the $3000–$4,500 incl. GST range in NZ with 4WD models toward the top of that band. Pricing factors includes, the use of genuine parts versus aftermarket and if you replace your water pump, which is highly recommended. Use that as your reference point when undertndning the costs, rather than a lighter, belt-only quote you might see elsewhere a job that skips the water pump isn't really the same job.

Worth Consideration because this job already requires draining the oil, it's often smart to combine it with a scheduled service — the oil and filter change is being done either way, so bundling avoids paying for that twice.