What Is a Wet Belt?

Wet belts were introduced in 2008 as an alternative to cambelts and timing chains. They promised better durability, cooling and lubrication - but have since developed a reputation for being problematic and unreliable in some vehicles.

This guide explains why wet belts are used, how they work, and why replacing them at the correct intervals is so important.

What is a wet belt?

A wet belt is used to control the engine’s timing. Specifically, it synchronises the top and bottom parts of the engine, known as the camshaft and crankshaft. This ensures the valves open and close at the correct time. You can learn more about how a car engine works in this guide.

Wet belts were introduced in some cars because they were believed to have several advantages over cambelts and timing chains. However, they aren’t the perfect solution they were initially thought to be. 

Pros

• Increased lifespan due to lubrication

• Reduced fuel consumption and CO2 emissions

• Better temperature management 

• Noise reduction

• Space saving

Cons

• Vulnerable to contamination

• Premature wear can lead to a clogged oil filter and oil starvation

• Detached material from the belt can damage the brake pump

On the surface, it seems like there are more pros than cons for wet belts. But the reality is that even the smallest amount of oil contamination from crystalline or soot particles can cause premature belt wear.

The outer material of the belt can detach and enter the oil as it wears out. Since the oil circulates the engine, these contaminants can cause damage to parts, including the oil filter and brake pump. 

A clogged filter will lead to oil starvation, severely damaging the engine. And a failed brake pump is, needless to say, extremely dangerous. None of these problems exist to the same extent for the traditional cambelt and timing chain solutions.

What’s the difference between a wet belt, cambelt and timing chain?

Cambelt

A cambelt is made of rubber or synthetic material. It is housed outside the engine, isn’t lubricated by oil and needs replacing roughly every 40,000 to 100,000 miles. The main advantage of a cambelt over a timing chain is that it is quieter.

Timing chain

A timing chain is made of metal. It is housed inside the engine, is lubricated by oil and needs replacing roughly every 80,000 to 120,000 miles. The main advantage of a timing chain over a cambelt is that it is more durable, so it doesn’t need replacing as often.

Learn how to find out if your car has a timing chain or belt.

Wet belt

A wet belt is usually made of rubber reinforced with corded fibres. It is housed inside the engine, is lubricated by oil and needs replacing roughly every 50,000 to 100,000 miles. The main advantage of a wet belt is that it provides better fuel efficiency and less CO2. 

However, many wet belts have failed prematurely, leading some repairers to recommend a more frequent replacement interval.

Why is engine timing so important?

Now you know about the different kinds of timing systems, you might be wondering why engine timing matters at all. In fact, it’s pretty crucial. It’s responsible for regulating the combustion of fuel and air by operating the valves in time with the pistons (pictured below on the crankshaft). In doing so, it affects various things, including your car’s performance and fuel economy.

Does my car have a wet belt?

You can find out whether your car has a wet belt by checking your owner’s manual. It will contain all the information you need, including the manufacturer’s recommended replacement interval and advice about maintenance.

What cars have wet timing belts?

Do you have to replace an engine wet belt?

Unfortunately, a wet belt won’t last forever. As the belt ages, it starts to fray and lose grip on the pulleys. If it snaps, it can cause severe and costly engine damage.

Replacing it isn’t optional if you want your car to keep running. Check your owner’s manual to determine how often you should change yours.

What can go wrong with a wet belt?

Wear and tear

When a wet belt wears out, bits of the rubber surface begin to fray. The smoother it becomes, the harder it is to find traction on pulleys. Eventually, this can lead to engine timing issues.

Contamination

Particles from the belt’s outer coating can come loose in the engine oil and damage other parts. The oil filter and pump are particularly at risk. If the filter is clogged, it will starve the engine of oil, leading to severe damage that's costly to fix.

Reduced traction

Wet belts are lined with teeth that create traction on the pulleys. As they wear out, they get smoother, making it much harder to maintain grip. This can throw your engine’s timing out.

Low engine oil

The wet belt relies on lubrication from engine oil. Without enough oil in the system, it will wear out faster and accelerate the wear of nearby components. Find out how to check your car’s fluid levels.

How often should you replace a wet belt?

You should replace the wet belt at the manufacturer-recommended intervals outlined in your owner’s manual. 

Ford typically advises a wet belt change every 10 years or 150,000 miles, while Vauxhall recommends every six years or 60,000 miles. 

Important: It’s worth researching forums to find out whether other owners of your car model have suffered premature wet belt problems. If so, you should aim to replace the part more frequently.

Signs your wet belt needs replacing

These symptoms could indicate a problem with your car’s wet belt.

• Engine misfires

• Illuminated check engine light

• Oil leak near the belt

• Erratic engine performance at high RPM

• Unusual noises, such as squealing and grinding

Learn how to diagnose car problems and find the right fix.

If you don’t replace your wet belt at the correct intervals, there’s a high possibility you won’t notice it wearing out until it’s too late. By that point, you could end up with engine damage that is more expensive than replacing the belt in the first place.

Book a wet belt replacement

FixMyCar can help you compare prices and find a reliable local garage for a wet belt replacement.

If you found this guide helpful, you might also like:

• How much does it cost to replace a wet belt?

• How much does a Ford wet belt replacement cost?

• How to find out if your car has a timing chain or timing belt

• How much does it cost to replace a cambelt?

• What happens when your cambelt is replaced?

• How does a car engine work?

• How often should you change your engine oil?

• How does a car work?