Fleets warned of 'engine killer' wet timing belts

Fleet operators are being warned of a potential reliability issue that affects numerous cars and vans produced since 2012 and could result in engine failure.

The use of 'wet belts' was introduced by some manufacturers to reduce emissions and increase efficiency, but the longevity of these powertrains was overestimated.

Citroen, Ford, Honda, Peugeot and Toyota are among the brands that have fitted wet timing belts to some of their cars.

Because the rubber belt is in constant contact with the oil, it can cause the belt to degrade more quickly, especially if the wrong type of oil is used. As a result, it may not last as long as the manufacturer's handbook states it should. 

Wet timing belts can also cause another form of engine failure: one that is unique to this type of belt. As the wet belt gradually picks up wear and tear over time, small particles come off the belt and are picked up by the oil. Because the belt and the oil bath are inside the engine, they are then circulated throughout the rest of the engine system. This can block or damage crucial engine parts and cause blockages in the system that prevent the engine oil from circulating, both of which will lead to engine failure. 

Mark Barclay, head of Ecommerce at My Motor World, said: "Without regular inspections and proper maintenance, wet timing belts can be an engine killer. To avoid costly repairs, owners of cars with this type of belt really have to be on it with their maintenance schedule. It might be annoying and expensive to keep checking and replacing the timing belt and changing the oil, but it's still cheaper than a new engine — or even a new car. It's a case of spending little and often to avoid spiralling costs further down the line. 

"If you have a wet timing belt, my advice would be to get regular inspections at a garage that's familiar with them, replace the belt at the first sign of deterioration, and keep that engine oil as clean as possible. And only ever use the exact type of oil that the manufacturer recommends. 

"It's hard to imagine what the engineers were thinking when they introduced this feature, given how unpopular it has become. But, it just goes to show that the rigorous testing cars undergo cannot catch every type of fault. "

Affected models:

• Ford: EcoBoost and EcoBlue vehicles, including the Fiesta, Puma, Ecosport, C-Max, Focus, Transit, Connect, and B-Max. 
• Peugeot: 208, 2008, 308, 3008, 5008, Partner.
• Citroen: Berlingo, C3, C4, C5 Aircross.
• Toyota: Aygo and Proace. 
• Vauxhall: PureTech engines, including certain Corsa, Astra, Granland, Crossland and Combo models
• Honda: Civic 1.0 litre Turbo  

After numerous engine failures, Ford was forced to revised the timing belt change interval for some of its diesel engines. The service interval for the timing belt, tensioner and idlers was reduced to six years or 160,000km (100,000 miles), from 10 years or 240,000km (150,000 miles). This applies to all Transit and Transit Custom, Van and Tourneo vehicles fitted with a 2.0-litre EcoBlue diesel engine.

For the Ecoboost petrol engine, Ford has been offering repairs on a goodwill basis for vehicles up to seven years old and with a full service history. The issues were highlighted in a BBC Watchdog investigation. In the USA, the car maker issued a recall for some models fitted with the Ecoboost petrol engine for faults related to the timing belt and is subject to a class-action laswsuit.

Stellantis has also taken action to address wet timing belt issues. It has extended the warranty on all petrol PureTech 1.0 and 1.2 engines, covering 100% of the costs for up to 10 years or 108,000 miles, under certain conditions. In 2023, Stellantis updated the powertrain to utilise a timing chain instead of a belt.

It has also opened a compensation platform for vehicle owners that faced repair expenses with these engines due to excessive oil consumption and/or premature degradation of the timing belt between January 1, 2022 and March 18, 2024. The platform can be accessed here.