29th September 2026
For years, one of the simplest pieces of advice given to car owners was: check when your cambelt is due and change it before it breaks.
It was usually a straightforward figure. Perhaps 60,000 miles or five years, perhaps 80,000 miles or eight years. The owner could look in the handbook, make a note of the date and mileage and budget for what could be an expensive but necessary job.
But finding that information is becoming less straightforward.
Car manufacturers have not stopped specifying cambelt replacement intervals. What is changing is how that information is provided. Increasingly, manufacturers say that the precise requirement depends on the particular engine, model year and vehicle identification number, with owners directed towards online maintenance systems or authorised dealers.
Ford provides a particularly clear example. Its current UK guidance says the exact replacement schedule is specific to the vehicle's model, engine variant and age. It says owners can check their service handbook or Ford account, while also advising them to contact an authorised Ford dealer with the vehicle's VIN for the definitive information.
That sounds like a sensible way of dealing with increasingly complicated cars.
But it creates a consumer problem.
What happens when the car is five or six years old, the original owner has disappeared and the second-hand buyer is relying on the information supplied with the vehicle?
The handbook may no longer be the whole story
Modern cars can have conventional cambelts, timing chains or what are known as wet belts, which operate inside the engine and are lubricated by engine oil.
The maintenance requirements can be very different.
Ford itself now tells owners that their vehicle could have a cambelt, timing chain or wet-belt system, depending on the model, engine and year. It says maintenance schedules can evolve and that dealers have access to the latest technical information and service actions linked to the individual VIN.
That is important because the car may have been built several years ago while the manufacturer's recommended maintenance information continues to evolve.
A second-hand buyer therefore needs to know not simply what the handbook said when the car was new, but what the manufacturer currently recommends for that particular vehicle.
That is not always obvious to someone buying a used car privately or from an independent dealer.
Wet belts have made the issue more complicated
The introduction of wet timing belts has attracted particular attention.
The idea behind a wet belt is not difficult to understand. Running the belt in oil can reduce friction and noise and allows manufacturers greater flexibility in engine design.
But it also means that the belt is part of a more complicated engine environment. The condition of the belt can be affected by the oil being used and by servicing.
If a belt deteriorates, material can potentially enter the engine's oil system. What looks like a relatively simple belt replacement can therefore become a much more serious engine problem.
This makes following the manufacturer's servicing requirements particularly important.
It also creates another problem for the second-hand car buyer.
A car can look perfectly healthy, pass its MOT and have a clean service history, while still approaching an expensive timing-belt replacement.
The MOT is not designed to tell you that the cambelt is approaching the end of its recommended service life.
A broken belt can be extremely expensive
The reason manufacturers have traditionally been so keen on scheduled replacement is simple.
The cambelt synchronises the crankshaft and camshaft so that the engine valves open and close at precisely the right time. If it breaks, the engine can stop immediately and, depending on the engine design, serious internal damage can result.
Ford warns that a broken timing belt can stop the engine and potentially cause damage. It also says the replacement job can take many hours because of the access required, with the water pump and other components sometimes replaced at the same time.
That makes it rather different from replacing a tyre or brake pad.
You cannot simply wait until the belt starts making an obvious noise and then decide to replace it.
The problem for the ordinary motorist
Most motorists are not engineers.
They quite reasonably expect the manufacturer to tell them what needs replacing and when.
That is why a simple statement such as "change at 60,000 miles or five years" was so useful.
Today the owner may instead be told to check the handbook, log into an app, use an online maintenance schedule or contact a dealer with the VIN.
Ford's current system, for example, allows owners to view maintenance information through their Ford account or app, while its maintenance schedule system can identify the vehicle using its registration or VIN.
This may be more accurate than a generic figure printed in every handbook.
But it also means that the responsibility for finding the latest information has increasingly moved towards the owner.
That is particularly important when buying a used car.
What should buyers do?
Anyone buying a used car fitted with a cambelt should establish three things.
First, does the engine have a cambelt, wet belt or timing chain?
Second, what is the manufacturer's current replacement interval for that exact engine?
Third, has the belt already been replaced, and can that be demonstrated by an invoice or service record?
If there is any doubt, the safest approach is to contact the manufacturer's dealer or use the manufacturer's official maintenance system with the vehicle registration or VIN.
Don't assume that because a previous owner says "the belt isn't due yet" that this is necessarily correct.
And don't assume that an old handbook necessarily contains the latest information.
A small change with a potentially large bill
There is a wider lesson here.
Cars have become enormously more sophisticated. Computers monitor oil condition, service requirements and faults. Manufacturers can now tailor maintenance information to the precise vehicle rather than giving every owner the same generic schedule.
That should ultimately be better for motorists.
But it does make car ownership more dependent on information systems that the average driver may not even know exist.
The old advice was easy:
Look in the handbook. Find the mileage and the date. Change the belt before it breaks.
The modern version is rather different:
Find out exactly what engine you have, check the manufacturer's latest schedule and make sure the information relates to your particular vehicle.
For anyone buying a used car, that difference could be worth hundreds or even thousands of pounds.
And perhaps the most important lesson is this:
If you don't know when your cambelt is due, don't wait for the car to tell you. Find out before the belt does.