Does Your Engine Have a Timing Belt?

Since the mid-70s, many import car engines have featured a timing belt to operate the single and double overhead camshafts of small displacement; usually under 3-liter (3000cc) engines. And in recent model years several small American-made engines now using timing belts to operate overhead camshafts. Now we are seeing even larger sized engines using a timing belt for overhead camshaft operation.

The timing belt is a strong, wide, square-toothed type of belt which is driven by the engine's crankshaft. Once installed and properly tensioned, a timing belt usually will operate without any further service or maintenance for 60,000 or more miles. Almost every engine with a timing belt also has a manufacturer’s recommended mileage for its replacement. Only a few carmakers offer no replacement recommendation. But to be safely conservative, some timing belt manufacturers suggest a maximum 60,000-mile replacement interval to avoid inconvenient and possibly costly engine damage. You see, when a timing belt breaks, it usually does so when the engine is running. This kind of operational breakage very often results in expensive

Engine damage, due to fast-moving pistons in the engine block Impacting valves which may be open. Not all timing belt breakage will end up causing serious valve-to-piston damage. Some engines are of the freewheeling type, that is, due to there cylinder head design, valves and pistons are very unlikely to collide, therefore no damage will occur.

Others are known as interference type engines, where valve-to-piston contact is almost sure to happen when the timing belt breaks. Replacing a timing belt will take between 2.5 to 5.5 hours, depending on how easy it is to make the change, given the limited under-hood space in many of today's cramped engine compartments. Prices will vary, depending on shop labor rates and the time needed for the job, but $200 to $500+ is the range for a straight timing-belt replacement.

We recommend that front engine seals also be replaced along with the belt. Oil seals are inexpensive and will leak eventually if not replaced with the belt. Some models also recommend water pump replacement at the same interval. Sound like a lot? If you drive until the belt breaks, you could be facing anything from a cylinder head overhaul to a major engine rebuild. Engine timing belt replacement is a required maintenance job on a growing number of engines today. So ... do you know how your engine's valves are operated? If it's with a timing belt, get to know the carmakers recommended replacement interval.