Most car owners who know something about cars have heard about the timing belt.
It is probably the car part which is most talked about. This is probably because of the expensive replacement cost and the disaster which happens if it snaps off.
In this article, we will discuss the symptoms of a bad timing belt, the location, and also the replacement cost.
6 Symptoms of a Bad Timing Belt
- Check engine light
- Slamming noise from engine bay
- Slow acceleration
- Rough or stalling engine
- Smoke from the engine
- High fuel consumption
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.
However, there are some symptoms you can see for some time before the timing 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!
Here is a more detailed list of the 6 most common symptoms of a bad timing belt.
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 sound from an area close to the timing belt, you should imminently shut off your engine and not start it before you have checked if the timing belt is causing this problem.
This normally happens because the timing belts get longer over time, and the timing belt tensioner reaches its bottom.
A bad timing belt can cause the timing 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 on the power of your car. If the timing 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.
Because of the reason we talked about in the previous symptoms – a bad timing belt that jumped over gears can also cause the idle to become rough and even stalling sometimes.
At idle, the car engine is most sensitive for problems, and it is probably here you will notice a bad timing belt first.
Smoke from engine
When the timing belt is getting worn, it can sometimes start to wander out from the engine. Around the timing belt is a plastic cover, and if the timing belt is wandering out – it will touch these plastic covers.
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 timing 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.
The function of a timing belt
The timing belt helps them camshaft to spin together with the crankshaft at a fixed speed. For every one turn that the crankshaft spins, the camshaft spins ½ a turn. This is because of the 4 stroke engine.
The timing belt spins the camshaft, which opens the valves at the exact right moment. If the timing belt is going bad and the crankshaft/camshaft timing is not correct anymore, you can imagine what happens if the valves don’t open at the right time.
Timing belt location
The timing belt is located on the front of the engine on most car models. It is often hidden under a lot of plastic covers and behind the serpentine belt.
Remember that your engine can be installed sideways, which most often will cause the timing belt to be located at the right side of your car, but still in the front of the engine.
This can make it really difficult to inspect properly for any damage. Some cars have a simple plastic cover on the top of the engine, though, to inspect the timing belt condition.
When Should a Timing Belt Be Replaced?
The replacement interval of a timing belt is heavily different between car models.
The timing belt’s replacement interval on newer cars is often between 75000 to 130000 miles or 120.000 to 210.000 km.
The timing belt’s replacement interval on older cars is often between 37000 to 75000 miles or 60.000 to 120.000 km.
If you want to know the timing interval on exactly your car and engine model, you need to check in the repair manual or call your authorized dealer. I do also strongly recommend checking this precisely because of the damage it will cause if it fails.
Timing belt replacement cost
The timing belt itself costs 30$ to 100$, but you often have to replace many other parts simultaneously, like pulleys, water pump, and more. This depends heavily on the car model, and the prices can differ a lot.
The labor cost of a timing belt replacement is often between 200$ to 1000$. You can expect a total cost of 300$ to 1500$ for a timing belt replacement on most cars.
The time to replace the timing belt can differ from 30 minutes to many hours, depending on the car model. For example, on many Audi models, you have to remove the whole front of the car to reach the timing belt. You can probably imagine that this will cost a little bit at a workshop.
Replacing the timing belt yourself without much knowledge is one of these things I really wouldn’t recommend you. A small mistake can result in a complete engine failure, so it is recommended to leave this to the professionals.
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Founder, owner & main author of Mechanic Base. I have been repairing cars for more than 10 years, specialized in advanced diagnostics & troubleshooting. I have also been a drifting driver and mechanic for over 7 years.