Timing belts are typically only used on overhead camshaft engines. Timing belts are used to synchronize the crankshaft with the camshaft, at an exact 2 to 1 ratio, similar to a timing chain used on other overhead camshaft and overhead valve (pushrod) engines. Unlike a timing belt, a timing chain is not considered a maintenance item, as many timing chains can last the life of the engine without needing service or replacement. To maintain a constant 2 to 1 ratio, timing belts use raised teeth to mesh with the crankshaft and camshaft sprockets to operate the valve train of an overhead camshaft engine.
The recommended replacement interval for the timing belt is under normal conditions every 84 months or 105,000 (168,000 km), miles whichever occurs first. For vehicles driven in severely hot (over 90°F or 32°C) or severely cold conditions (below -20°F or -29°C), the belt should be replaced every 60,000 miles (96,000 km), or every 84 months whichever occurs first. Refer to Engine and Engine Overhaul for timing belt replacement procedures.
If the vehicle has been purchased used with an unknown service history, refer to the maintenance charts provided in this guide to compare the vehicle age and mileage to the recommended maintenance intervals.
Engines can be classified as either free-running or interference engines, depending on what would happen if the piston-to-valve timing were disrupted, which would occur should a timing belt fail. A free-running engine is designed with enough clearance between the pistons and valves to allow the crankshaft to continue to rotate (pistons still moving) while the camshaft stays in one position (several valves fully open). If no other engine related failure occurs, it is likely no further internal engine damage will result. In an interference engine, should the timing belt fail, there is not enough clearance between the pistons and valves to allow the crankshaft to continue to rotate with the camshaft in one position, and the pistons will contact the valves causing internal damage. When this type of failure occurs, the engine will need to be disassembled and evaluated for repair or possibly replaced. Either choice is an expensive one, many times that of replacing the timing belt.
See Figures 1 through 7
All of the Honda engines covered by this guide utilize timing belts to drive the camshaft from the crankshaft's turning motion and to maintain proper valve timing. In addition to the belt driven camshafts, the 4-cylinder Odyssey engines also have belt driven balance shafts. This belt is similar to the timing belt that drives the camshaft, though it is a separate belt and follows the same maintenance intervals as the camshaft drive belt.
The belt should be checked periodically to make sure it has not become damaged or worn. A severely worn belt may cause engine performance to drop dramatically, but a damaged belt (which could fail suddenly) may not give as much warning. In general, any time the engine timing cover(s) is (are) removed, inspect the belt for premature parting, severe cracks or missing teeth
Inspect both sides of the timing belt. Replace the belt with a new one if any of the following conditions exist: