How To Change a Timing Belt

Timing belts provide a flexible connection between the camshaft and crankshaft to keep the valves opening and closing in phase with the movement of the pistons. In many engines the pistons and valves occupy the same "air space" and would crash into each other causing severe engine damage if the timing belt failed and did not facilitate the correct "phase" between the camshaft and crankshaft. These engines are called "interference" engines and a failed timing belt usually means a huge engine repair bill.

Non- interference engines are those that have enough space to accommodate both piston and valve without touching each other. If a timing belt fails the engine will simply stop.

Manufacturers list the recommended schedule for changing belts and it's typically somewhere between 60,000 to 100,000 miles. However, if you live in a hot part of the country be sure to read the fine print as the change mileage will be significantly less.

Note: The following list is general in nature. You will need a technical manual for your particular make, model and year to determine if special tools are required:

• Correct replacement timing belt
• Technical manual
• Ratchet with extensions
• Socket set
• Torque wrench
• Harmonic Balancer Puller
• Screwdrivers
• Timing belt cover gaskets
• Jack stands

In most cases this will be your first time changing the timing belt in your car. Set aside enough time to allow you to do a thorough job and to work through any complications you may encounter. Start by reading the technical manual so you have a solid familiarization with the process. Have all your tools available before you start the project. As you remove bolts and parts, have a place where you can keep them in an organized fashion. You may want to use your cell phone to capture "before" pictures before performing a particular task to use as a reference when reassembling.

Note: These are general instructions for a vehicle with an electronic ignition. You will need a technical manual for your particular make, model and year to determine if other steps are required.

1. Disconnect the negative cable from your battery.
2. The next steps deal with getting to the timing belt. The first step is to remove the alternator belt. This may require loosening the alternator bolts and pushing it down to create slack to remove the alternator belt.
3. You may have to remove or move accessories like the power steering pump and a/c compressor to get to the timing belt.
4. Find the cam and crankshaft position sensor and make certain the first cylinder is set to Top Dead Center (TDC). Refer to your manual for instructions.
5. Use a wrench or socket on the crankshaft bolt to rotate the engine until the timing mark on the crankshaft pulley is aligned with the 0° mark on the timing scale.
6. Many times the harmonic balance pulley will be positioned so that it blocks access to the crankshaft. If this is the case remove it. You'll need new seals for the cover when you reinstall it.

1. Remove the bolts holding the timing cover in place. On some models the timing cover may actually be a two piece unit. Remove all bolts and pull the cover off.
2. Check for the correct alignment of the crank and camshaft timing marks. Most engines have a dot or line on the pulleys and/or sprockets that has to be lined up with corresponding marks on the block, cylinder head, or accessory shaft. If these are not lined up consult your technical manual to determine how to adjust.
3. Take this opportunity to check for leaks around the belt. If you spot oil or fluids it's best to track down the source and repair before installing the new timing belt.
4. Loosen the mounting bolts for the spring loaded belt tensioner. Push the tensioner out of the way and then tighten the bolts to keep it out of the way.
5. Slide the old belt off the sprockets. You may need a screwdriver to pry the belt off the pulley grooves.
6. Slip the new belt on and then reassemble. Pay particular attention to torque requirements when reassembling.

These instructions are meant as guidelines and are not comprehensive. However they should give you a good idea what is involved and the skill level necessary. For detailed instructions always rely on a quality technical manual for your make, model, year and engine type.

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