There seems to be a lot of confusion about when the timing belt is due for a change.
In a lot of service manuals and owners handbooks are intavals quoted of up to 80,000 miles and up to 10 years. This might have been the general consensus at the time being an we are not disputing this at all.
The largerst timing belt provider to automotive industries (at time of writing) is Dayco. Dayco supplies timing belts to the production line as well as to all after market suppliers.
Dayco has revised the timing belt changing intervals to 36,000 or 3 (three) years. This is due to the fact that the belt failure rate has increased in recent years dramatically over the three year period. This is not due to lower manufacturing quality. The stresses in the environment in more modern engines are much increased and therefore can't last as long as in comparatively less stressing conditions.
The fact that a lot of timing belts do not snap well above the three year period or the 36,000 should not lead to the conclusion that it is not necessary to change the belts earlier than the previously promoted recommendations.
Everyone be advised that the intervals set by Dayco are a safety recommendation to safeguard many engines that might suffer valve damage in case the timing belt brakes. But more importantly the manufacturer is also aware that a broken timing belt might bring the driver and other occupants of the car into life threatening danger, which might even extend to members of the public that are passers by.
It is therefore rather wise to change the timing belt at 36,000 or three years or if not known when it was done rather the earlier than later.
If anyone would like to argue about it with anyone here, just point to this thread.
