Signs Your Timing Belt Is Failing

Stephen Fogel
April 4, 2018

Your engine relies on perfect timing. As it goes through its four strokes — intake, compression, combustion and exhaust — it relies on the camshaft or camshafts to open its valves and the crankshaft to move its pistons, all without them crashing into each other. The timing belt or timing chain plays a big role in this.

Let’s look at some of the symptoms of a bad or failing timing belt:

1. Engine runs poorly: A worn timing belt can slip, getting out of the proper alignment. This means that the valves and pistons are no longer perfectly synchronized. Your intake and exhaust valves won’t open and close at the right times, which can cause misfires or less acceleration power. A failing belt may also cause the engine to shake as it slips. 

2. Illuminated check engine light: The car’s computer monitors engine operation to ensure emissions don’t get too high. A malfunctioning timing belt will hurt engine performance and increase emissions. If this happens, the computer will turn on the check engine light.

3. Ticking sound coming from engine: A failing timing belt can cause a ticking noise when the car is running. This is typically a sign that you have low oil pressure or that the engine isn’t getting enough lubrication.

4. Engine won’t start: If the timing belt is completely broken, the car won’t even be able to start. You may hear the starter motor turning, but nothing else. You’ll need a mechanic to assess what repairs may be necessary. If the belt broke when the engine was off, you may avoid major repairs. If the engine was running when this happened, there is likely to be major internal damage.

5. Loss of oil pressure: This can result from damage to the camshafts as the timing belt slips. Pieces can break off from the misaligned camshafts and end up in the oil pan, where they can prevent oil from flowing to the engine. 

6. Leaking oil: If the nuts and bolts that secure the timing belt cover start to come loose, or the gasket between the engine and cover wears out, you can experience an oil leak. Over time, the belt can deteriorate from steady exposure to oil or other fluids. 

Get it diagnosed by a professional

What is a timing belt?

The belt is made of rubber or a synthetic material, and is reinforced for extra durability. It is usually toothed or ribbed. It attaches to the camshaft, in the top half of your engine, and the crankshaft in the bottom half, ensuring that they turn at the correct speed and time so that your engine runs smoothly. In some cases, the timing belt may also drive additional components, such as the water pump and balance shaft.

It’s critical to know the service needs of your timing belt. Most timing belts will need to be replaced as part of regular maintenance every 60,000 to 100,000 miles, and most related problems are caused by not replacing it when you’re supposed to. The consequences of a failed timing belt are very serious, with the worst-case scenario being catastrophic engine failure.

Timing belt vs. timing chain

So, what’s the difference between a timing belt and a timing chain? Well, there’s the obvious — one’s a belt and one’s a chain — but each has an advantage.  A timing belt will run more quietly but will need to be replaced as part of regular maintenance every so often. Meanwhile, a timing chain will make more noise but is stronger and longer-lasting. Both can cause a lot of damage to your engine if they break. 

Timing chains tended to give way to timing belts in cars made in the 1970s and ’80s, largely due to the fact that belts run quieter and are cheaper to maintain. But timing chains have made a comeback in the past decade or two because of their longer life expectancy and the fact they typically give warning signs before breaking.

Fixing a bad timing belt

If you have the ability and the tools to remove your timing belt cover, the physical appearance of the timing belt can provide clues to its condition. A good timing belt should display none of these symptoms. Here are some visual clues that your timing belt is in trouble:

  • Teeth are worn down
  • Teeth are sheared off
  • Teeth are hollowed out
  • Edges of belt are worn
  • Back of belt is cracked
  • Belt is soaked with oil
  • Belt is broken

The fix for a bad timing belt is to replace it. Replacing a timing belt requires a moderate level of skill, so this is usually a job for your mechanic

If there is oil or other fluid leaks present, they should be fixed at the same time so the fluid doesn’t shorten the lifespan of the new belt. If any other parts were damaged by a failed belt, they will need to be repaired or replaced.

Accessing the timing belt usually involves removing several of the accessories that are attached to the engine in the area of the belt. The timing belt cover is then removed so that the belt can be accessed. 

At this point, it might be smart to have related work done to help save on labor. Parts such as pulleys, serpentine belts, tensioners and the water pump are usually worth replacing if they show wear or signs of failure.

Next comes reassembly. The key part of a timing belt repair is to make sure that the timing of the engine is correct after the belt has been replaced. This normally involves verifying that the timing marks on the engine are properly aligned so that the crankshaft and the camshafts are synchronized correctly. 


Stephen Fogel

About the Author

Stephen has been an automotive enthusiast since childhood, owning some of his vehicles for as long as 40 years, and has raced open-wheel formula cars. He follows and writes about the global automotive industry, with an eye on the latest vehicle technologies.

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