Many cars today use timing belts instead of timing chains that were used in the past. Most import automobiles use them and some new domestic autos are switching to them. There are advantages and disadvantages to using timing belts. Timing belts are more quiet than a timing chain. This is good for high performance applications that use knock sensors to detect detonation. The lesser noise minimizes the background noise caused by a timing chain. The downside is that the timing belt should be replaced every 60,000 miles. A timing chain will generally never need to be replaced. Many times people will wait past 120,000 miles and their belt will break. If the timing belt breaks the car will stop wherever it happens to be. Depending on what type of car you own the timing belt breaking can be very costly.
Some engines use interference valve engines which means the valves open far enough to hit the piston if not kept in time. If this happens the whole engine may be no good due to bent valves, broken head parts, broken pistons and possible cylinder wall damage.
This is a mazda miata and the highlighted arrows show all of the spots that need to be loosened or removed. The air crossover pipe has already been removed and connects between the airflow meter and the throttle body. The ignition coils are located on the back of the valve cover and are easily removed.
You will want to remove these three bolts for the water pump pulley before you remove the accessory belt. To remove the belt loosen the upper and lower alternator bolts. Then on the left side loosen the 12 mm bolts and remove the tension on the belt. The belt will easily come off. If you have a/c or power steering you will need to remove that belt also. Place your car in neutral with the parking brake on. You will want to line up the T on the timing marks and the notch on the pulley. This is the timing for the crankshaft. Check to make sure the top cam marks are lined up from straight on as shown below (they look one tooth off in the picture but they are not).
If not place car in neutral, rotate the engine until they both line up, assuming the belt has not already moved. Then you will need to place you car in 5th gear or park and set the parking brake. Then place a socket on the crankshaft bolt as shown above and connect a long breaker bar to the socket to remove it. There are also four 10 mm bolts that will need to be removed. The pulley and plates may need to be gently pried off or tapped to come loose. When removed it will look like the picture below. There is also a timing mark on this inner pulley and the engine block to confirm the timing has not moved. After the water pump pulley is removed there are two plastic covers that will need to be removed to access the timing belt. You will want to remove the two bolts shown in the picture below located just below the pulleys. This will allow the upper plastic cover to come out from under this top cover.
At this point you have a couple of options depending if you want to replace the water pump or not. Generally most people will replace it because otherwise you may have to repeat this whole process over again if the water pump were to fail. If you decide to replace it follow this to Water Pump. If not, here is an easy way to cheat the timing. Cut half way into the belt width and rip the belt length wise until the belt is half it’s original width. Slip on the new belt up against the old belt then cut the old belt all the way off. Push the belt the rest of the way on and your done, other than reassembling. If you decided to remove the water pump, good move, you had to cut the belt off, don’t worry it’s not that bad. You will want to loosen the center bolt to the left idler pulley on the water pump. When the bolt is loose slide the idler away from the center and tighten the bolt again. That will make room for the belt for now, but you will loosen again to add tension after the timing belt is in place.
If you scroll back to the very first story you will see there is a zip tie on the right cam pulley. This will hold the belt in place until you line up the other pulley. You can then apply a zip tie to this pulley also or you can try to apply it to the crankshaft pulley. After the timing belt is on, reconfirm that the timing marks are still lined up after the left idler is tightened up against the belt. Your done, that is after you redo everything you had to undo. The center bolt for the crankshaft pulley needs to be torqued to 120 foot pounds of torque. Also don’t forget to get the accessory belts tight.