Q. Sings of a Bad or Failing Timing Belt
- Ticking noise coming from the engine. The timing belt is connected by way of a series of pulleys to the engine’s crank and camshaft.
- Engine misfires.
- Engine won’t turn over. The engine will not be able to turn over or ignite if the timing belt has broken inside.
- Oil leaking from in front of the motor
Q. When should you replace your car’s timing belt?
- The old rule was every 100,000 km. As technology has progressed, many manufacturers recommend intervals up to 160,000 km. You should examine what the vehicle’s manufacturer suggests and stay within that range to be safe.
- Engine stops shortly or will not start. Occasionally, timing belts can skip, or break, while the engine is running.
- Rough engine operation. The molded, reinforced teeth on the timing belt engage gears on the crankshaft and camshafts. The teeth can wear or break or the belt can stretch after many tens of thousands of miles, causing the belt to jump position on the crankshaft or camshaft gears as a result. If the belt jump, the engine will run inefficiently and sometimes not at all.
- Banging or clanking engine noise. On some engines, the pistons and valves can collide and there will be noise and damage if the timing belt has jumped. These engine designs are referred to as interference engines. If your car has an interference engine, switching the timing belt according to the maintenance schedule will reduce the chance that a belt failure will cause engine damage.
Q. How it’s done
Engine designs vary so the replacement procedure will also vary, but broadly, the procedure is as follows:
- Detach the battery ground cable.
- Once the engine cools, set the crankshaft to top dead center with the number one piston on the compression stroke. Take out crankshaft pulley.
- Remove all accessories interfering with the removal of the timing belt covers.
- Take out timing belt covers. Lock camshafts, as needed, and note position of camshaft timing marks. Remove timing belt tensioner and idler pulleys. Take out timing belt.
- Do so at this time if you’re planning on replacing the water pump, but first, drain the cooling system. If the engine cooling system thermostat is only accessible with water pump replacement, the thermostat should be replaced as well.
- Installation of the new timing belt includes all of the above steps, performed in reverse, following strict guidelines to guarantee camshaft and crankshaft (and balancing shaft, if equipped) are in perfect alignment after tensioner has been set.
- The engine crankshaft is turned by hand 720 degrees and the correct position of the timing marks on the crankshaft and the camshafts is ensured upon completion of the installation.
- The vehicle is road tested to check normal operation and a service sticker is affixed to the engine noting the date of belt replacement and the vehicle mileage.
Q. Is it safe to drive with a timing belt problem?
No, if a worn out timing belt to snap while underway, maybe on a highway, it poses risk of complete loss of engine power while surrounded by fast moving vehicles. You can remove the risk of unexpected and sudden timing belt breakage by having it replaced once your vehicle has reached the suggested replacement mileage for the belt. If your engine is of the interference type, it is particularly important to change the belt according to the maintenance schedule since sudden breakage of the timing belt, while the engine is running, will likely cause substantial damage to internal engine components such as the valves and pistons.