6 Symptoms of a Bad or Failing Timing Belt

It is important to change the timing belt in time as a failed timing belt can seriously damage your engine. This is how to tell your timing belt is bad.

Broken Timing Belt

The timing belt is probably the part on a car that is most talked about. This is probably because of the expensive replacement cost and the disaster which happens if it snaps.

If you have a broken timing belt, your engine will die immediately. If you have a newer car, it will also cause the valves to hit the pistons – which will be a very costly repair. Let’s begin with a quick look at the signs:

The most common symptom of a bad timing belt is a check engine light on your dashboard. You may also hear strange noises coming from the engine while running.

You can also notice issues like slow acceleration or a rough or stalling engine.

However, there are some symptoms you can see for some time before the belt fails. Because of this – if you see any of these symptoms and think it’s a bad timing belt, shut off the engine immediately!

Check Engine Light

The first thing you will notice if your timing belt is on its way to failure is a check engine light on your dashboard.

Most modern cars have a camshaft and crankshaft position sensor, which calculates the crankshaft position and the camshaft. If one of these positions is slightly out of the range – the check engine light will light up, and a trouble code will be stored in the engine control unit.

If you have a check engine light on your dashboard with a trouble code related to the camshaft position, it is definitely time to check the timing belt.

Slamming from engine bay

If the timing belt is very close to its last days, you might hear the timing belt slamming against the covers.

If you hear this slamming or ticking noise from an area close to the belt, you should imminently shut off your engine and not start it before you have checked if the belt is causing this problem.

This normally happens because the belts get longer over time, and the belt tensioner reaches its bottom.

Slow acceleration

A failing timing belt can cause the belt’s teeth to jump over 1 or 2 gears on the camshaft gear. This will cause the camshaft timing to advance or retard.

This is most noticeable in the power of your car. If the belt jumps over 2 gears, your car will be very slow and powerless.

If your car is very slow and powerless and you suspect the timing belt to be the problem – it is definitely time to check it.

Rough/Stalling Idle

Because of the reason we talked about in the previous symptoms – a bad belt that jumped over gears can also cause the idle to become rough and even stalling sometimes.

At idle, the car’s engine is most sensitive for problems, and it is probably here you will notice a bad timing belt first.

Smoke from engine

When you have a worn out timing belt, it can sometimes start to wander out from the engine. Around the belt is a plastic timing cover, and if the belt is wandering out – it will touch this timing belt cover.

Rubber against plastic can create smoke from your engine, and if you see this, it is definitely time to shut off the engine.

High fuel consumption

Because of the loss of power that happens when the belt is bad – as we discussed before, the car will also have to fight harder to hold its speed.

This will cause a significantly higher fuel consumption. So, if you feel that you have higher fuel consumption and a powerless engine, it could be a timing belt on its way to failure.

Written by:

Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.