Car service guide: What is a Wet Timing Belt?
Traditionally there are two methods for synchronising an the components on an internal combustion engine, these are the timing chain and the cam belt. Although they do the same job in principle there are some key differences between the two systems.
A timing belt or cam belt is an externally housed rubber belt that synchronizes the rotation of the crankshaft and camshaft(s) in an internal combustion engine. This synchronization is crucial for proper engine operation because it ensures that the engine's valves open and close at the correct time, allowing for the intake of air and fuel and the expulsion of exhaust gases.
A timing chain by contrast is a metal chain which is generally considered the more durable option of timing synchronisation. Crucially with a timing chain, the chain circulates through the oil supply of an engine to keep itself lubricated, reduce friction and dissipate heat. These systems generally last the life time of an engine and require less repair work than belts to keep operational - maintenance and inspections are still recommended though.
Recently we have seen manufactures using a wet belt setup which aims, in theory, to combine the best qualities of both the cam belt and cam chain systems. This means that a rubber belt is run through the engines oil supply in an effort to increase its lifespan. One example of this is the Ford Eco boost engine which has been part of their range since it debuted in 2012.
Car servicing: What are the advantages of a wet cam belt?
Lubrication: The primary reason for submerging the timing belt in oil is to provide constant lubrication. This lubrication reduces friction and wear, which is especially important given the high speeds and stresses that a timing belt experiences during engine operation.
Cooling: The oil surrounding the timing belt helps dissipate heat generated during the belt's movement. This cooling effect helps prevent the belt from overheating and deteriorating prematurely.
Noise Reduction: Wet timing belts tend to be quieter than dry belts, which can enhance the overall driving experience by reducing engine noise.
car servicing: What are the disadvantages of a wet cam belt?
Complex Maintenance: Wet timing belts can be more complex to maintain than dry timing belts. The presence of engine oil requires regular oil changes and careful attention to oil quality, as contaminated or degraded oil can adversely affect the timing belt's performance. For this reason we always use manufacturer approved oils when servicing wet belt driven vehicles.
Contamination: When wet belts begin to degrade small fragments will break away from the belt and become mixed into the oil supply. This can cause serious issues including a loss of oil pressure and complete engine failure. This is why it is so important to use the correct oils and follow servicing schedules rigorously.
Should I buy a car with a wet timing belt?
That depends on the mileage and age of the vehicle. We wouldn't advise against purchasing a well looked after vehicle with low mileage purely because it utilises a wet cam belt system however, you must keep up with servicing intervals to ensure a trouble free experience.
We would advise against purchasing a high mileage example without first making certain that the service history is solid and that the belt has been changed on time. If the belt is coming up for replacement time you should anticipate the fact that this can cost in excess of £1200 and factor that into any deal you make.