How to Detect and Change a Faulty Timing Belt

March 13, 2012

Allowing a timing belt to break can have drastic consequences. Early detection requires being on the lookout for 3 telltail signs.

Faulty Timing Belt

The timing belt in your car's engine is a ribbed or toothed belt driven by the crankshaft. It operates your vehicle's camshaft. The timing belt causes of the valves in your engine to open and close at the appropriate time. If it breaks while the engine is running it can result in serious damage to the engine. It's important to know what to look for in a faulty timing belt, and when to replace it.

Most vehicle manufacturers recommend that you change out the timing belt in your vehicle every 40,000 to 60,000 miles. If you live in areas where the temperature is either very hot or very cold, you may want to consider keeping a closer eye on your timing belt, and change it out more frequently. A timing belt won't last as long in extreme temperatures as it would in a milder climate.

What to Look For in a Faulty Timing Belt
You should occasionally inspect the timing belt in your vehicle to make sure that it's in good condition. When inspecting the belt, look for cracks or chips, and for teeth or ribbing that appears to be missing. You should change the timing belt if you notice any cracking or fraying, to avoid potential breakage. If you notice problems, do not delay. Purchase a new belt and install it yourself, or take it to a garage for to have a timing belt replacement done by a professional mechanic.

3 Symptoms of Your Timing Belt Not Working

  • A high-pitched sound. As the timing belt wears out, it starts to produce a high-pitched shrieking or whirring sound. You should be able to hear this especially as you start the engine up. When the engine is idling you may hear the sound as well. If you think that you hear an unusual sound of any kind, it's a good idea to stop your car and examine the engine. Leave the engine running and open up the hood, being careful not to touch anything that could be hot. This will allow you to better determine what is making the sound
  • Visual damage. You can also access the timing belt and inspect it visually. Spots of oil or coolant are signs that the belt is wearing out. A good, healthy belt should be entirely clean and free of these spots or other signs of wear and tear.
  • Difficulty starting up. Timing belts that aren't working will cause your vehicle to have a hard time starting up. If it takes several tries to get the engine to catch, there are many potential problems that could be responsible. The timing belt is one of the most likely

How to Change a Timing Belt

Changing your timing belt can be fairly difficult if you don't know what you are doing. Despite this you can successfully do it yourself if you take your time and follow the steps listed here. Before you begin, it is important to know that these instructions are general in nature. Each vehicle may require a few unique steps depending on the make and model. Use of an auto repair manual is recommended when performing this repair.

Disconnect Electronics
Before you begin you should disconnect the negative battery cable. Next remove the distributor cap if you have one. Most modern cars don't actually have a distributor anymore and instead have electronic ignitions. If that is the case make sure you can tell where the top center position is. This may require the use of an auto repair manual.

Set the Crankshaft
Using a wrench or socket rotate the crankshaft bolt until the timing mark on the crankshaft if lined up with the 0 degree mark on the timing scale.

Check the Distributor Rotor
Verify the distributor rotor is aligned with the index mark on the distributor housing. This indicates the rotor is in position to fire the number one cylinder. If not make sure you rotate the engine another full turn.

Access the Timing Belt Cover
Remove any obstructions or components that may be in the way of removing the timing belt cover. This includes any accessories or other belts that may be in the way. This step could be vastly different for each vehicle and you should consult your auto repair manual for any assistance.

Remove the Timing Belt Cover
Remove any bolts or screws from the timing cover and then remove the cover from the engine. Some engines actually have two-piece covers.

Check the Timing
Double check for the proper alignment of the crank and crankshaft timing marks. Most engines have a dot, line or other mark on the pulleys or sprockets that must be aligned with those marks on the engine block, cylinder head or accessory shaft. This mark can often be difficult to detect and your auto repair manual may prove invaluable for finding it.

Loosen the Tensioner
Loosen the timing belt tensioner. Some vehicles may require specials tools for this step. Usually these tools enable you to reach a tensioner that would otherwise be difficult to access.

Loosen the mounting bolts holding the tensioner but do not remove it. Next pry the tensioner away from the belt then re-tighten the mounting bolts to hold the tensioner in this new, loose position. During this step it is good idea to examine the pulleys or sprockets for any cracks or damage before you replace your belt.

Remove and Replace the Belt
The belt should easily slide off (if damaged) or on (if new) with the tensioner in this loose position. When replacing the belt, make sure you do not rotate the crank and that the timing marks continue to remain aligned.

Reassemble the Engine.
With the new belt in place reassemble the engine. Begin by returning the tensioner to its rightful position. Set the tension of the timing belt as per the vehicle specifications. With your vehicle reassembled you are now finished and your new timing belt has been successfully installed.

The Average Cost of a Timing Belt Change

The total timing belt change price will be determined by a number of factors. What tools you have and which ones you need to either buy or rent is one of the biggest factors in the total cost if you do it yourself. If you own none of the tools and you plan on doing the work, you can expect to pay as little as $50 if you shop around for the best prices. At most retail chain parts stores, the belt will cost between $20 and $40. With a set of complete instructions, preferably with pictures, someone with little to no experience can complete this project in an afternoon. For most cars, you will need nothing more than a set of sockets and a few wrenches. If you have a front wheel drive car, you may need a jack.

If you take it somewhere to have the work done, expect to pay anywhere from $100 at the extreme low end, to as much as $300 on the high end.

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