Timing belts in oil (B-I-O), also known as wet belts, have been fitted to some engines to help keep noise levels down and reduce friction. The belt runs inside the engine constantly bathed in engine oil. One popular B-I-O engine is the 1.0-litre EcoBoost 3-cylinder from Ford, launched in 2012. Fitted to the B-MAX, C-MAX, EcoSport, Fiesta and Focus models with power outputs of 100PS, 125PS and 140PS. Plus a year later in the Mondeo and Transit Courier.
Ford used the EcoBoost name (direct injection turbocharged) in other engine sizes – 1.5, 1.6, 2.0 and 2.3 – the latter used in the Focus RS and Mustang. These are all 4-cylinder units, however they DON’T run timing belts in engine oil – some are chain-driven.
The 1.0 EcoBoost won international Engine of the Year three times in a row in the early years (2012-14) – it’s a good engine when it is running well.
Problems are now coming to light as these engines head to a decade old and beyond. Ford specify 150,000-mile or 10 years (whichever comes first) timing belt changes. The correct Fordspec oil is required to keep the engine healthy, but even those with full Ford service history have been known to fail.
Once the timing belt change schedule approaches, the car may be on its 3rd, 4th or 5th owner – which is when they ‘may’ find or are advised by a garage that the wet belt is due a change. Then shock – the realisation that a 1.0-litre EcoBoost engine has a near 8hr job time to change a wet belt.
But as you will read, 150,000 miles or 10 years isn’t being reached in the real world. The timing belt loses teeth in service, then the shredded fibres block oilways, with some engines locking up. A secondary belt runs from the crank to the oil pump (known as the oil pump belt). This also suffers (or is the first to suffer), causing low oil pressure issues. Turbocharger wear will also be a factor to consider.
The belt tensioner is to blame for the belt failure. The tensioner’s water-proof joint breaks down from vibration over the vehicle’s service life, allowing the tensioner arm to fall out of position. It can impact the balance shaft, damaging the tensioner and straining the belt,
