A timing belt keeps the crankshaft and camshaft(s) in sync. On an interference engine, a broken or skipped belt can allow valves and pistons to collide, turning a routine maintenance job into an engine repair. When the belt is due, most professional technicians replace more than just the belt.
Why Replace More Than the Belt
The tensioner, idler pulleys and, on many engines, the water pump are driven by the timing belt and sit behind the same covers. These parts wear at a similar rate to the belt itself. If one of them fails after the job is done, the new belt can be damaged and the labor has to be repeated.
- Tensioner: keeps the belt at the correct tension. A weak spring, a leaking hydraulic tensioner or a worn pivot can let the belt flap, jump a tooth or wear prematurely.
- Idler pulleys: worn bearings can become noisy, seize or wobble, which can shred the belt edge.
- Water pump: when it is belt driven, a leaking seal can contaminate the new belt with coolant, and a worn bearing can cause the belt to track incorrectly.
Signs the Timing Belt Components Need Attention
- The vehicle has reached the replacement interval in the service information.
- Cracks, missing teeth, glazing or oil and coolant contamination on the belt.
- Whining, chirping or rattling from the front of the engine.
- Coolant seepage at the water pump weep hole.
Installation Tips
- Fix the source of any oil or coolant leak before installing the new belt. Camshaft and crankshaft seals are often replaced at the same time.
- Follow the timing marks and locking procedure for the specific engine, and rotate the engine by hand through at least two full crankshaft revolutions to recheck the marks before starting.
- Set belt tension exactly as specified. Over-tension shortens bearing life, while under-tension can allow the belt to skip.
- Refill and bleed the cooling system using the correct coolant type when the water pump is replaced.
Evergreen Timing Belt Components
Evergreen offers timing belt components including timing belt kits, kits with a water pump, tensioners and idlers. Use the Evergreen eCatalog to find the correct kit for the engine.
