If you already know all about timing belts, the easy answer is that your timing chain does pretty much the same thing. There are, however, differences in how they work, the jobs they do, how long each lasts, and what they cost.

So, in true Fixter fashion, we’re going to look at all of those elements and clear matters up once and for all. We’re going to talk about the advantages and disadvantages of a timing chain over a belt, how long they last, how they came in and out of favour, and we’ll also look into how much to replace a timing chain.

What is a timing chain?

A timing chain is responsible for controlling your pistons and valves, making sure they operate precisely when they need to inside your engine cylinders. Four-stroke engines operate on a cycle with, yes, you guessed it, four strokes within each one.

  • Intake stroke
  • Compression stroke
  • Power stroke
  • Exhaust stroke

Throughout one cycle, your camshaft spins once, and your crankshaft spins twice. During that phase, those four separate strokes happen. This is what’s known as mechanical timing or synchronisation—or simply ‘timing’ for short.

The job of your timing chain—or belt—is to operate the precise operation of the cycle and its strokes. If the pistons and valves don’t fire or move exactly when they should, your engine won’t work, or worse, suffer severe damage.

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

A timing belt is a heavy-duty rubber belt, with teeth along one side that fit into a series of pulleys and cogs that control your engine timing. If you open your bonnet, you should be able to see the rubber belts, or if not, a plastic case or cover where they’re sat.

A timing chain is a heavy-duty metal chain—something that looks a lot like a bicycle chain—but if you try to spot it when you lift your bonnet, you won’t. Your timing chain works inside the engine casing as it needs lubricating (with engine oil) to keep it in good condition and to operate as it should. It also requires oil to control the tensioners that keep it nice and snug.

Why have two systems that do the same job?

In the early days of motoring, all cars were built with timing chains. During the 1960s and 70s, a replacement system (rubber timing belts) was introduced, down easier to manufacture, resilient, durable materials.

The new rubber timing belts were much quieter than chains and were a lot easier to access and replace.

However, all that glitters is not gold. The argument for chains over belts landed back on the table during the 1990s.

Today, there are plenty of manufacturers who have reverted to fitting timing chains to their vehicles as standard, and many into particular models where they feel the advantages make them the best component for the job.

Most BMWs and Mercedes cars use driving chains. Some of the bigger American and European marques including Cadillac, Chevrolet, VW and Renault use timing chains in a selection of their models. It’s not just the big power brands either; you’ll find timing chains in some popular Dacia models, the Honda Jazz, as well as in selected Fords, Citroens, Fiats, and Mazdas.

Timing chain advantages and disadvantages

Advantages:

  • A chain offers superior strength, giving it a far longer lifespan. Hopefully, with proper care and maintenance, a timing chain should last the lifetime of your vehicle.
  • Maintenance is simple—keep up with your oil changes and consider a one-off check at the 125k-mile mark.
  • A metal chain is heat resistant, so isn’t vulnerable to changing conditions in the weather. A rubber belt can freeze in low temperatures, affecting performance.

Disadvantages:

  • A timing chain is much heavier than a rubber timing belt. This increases fuel consumption, and in turn, affects your fuel economy, adding to pollution, and impacts engine power.
  • A timing chain is far noisier than a timing belt.
  • Due to the extra weight, a timing chain is often only available for use on larger engine