Type Engine

An interference engine is one in which the valves, when at their maximum open position, protrude into the cylinders to the point that the pistons could hit them, IF the pistons were at top-dead-center at the same time. The timing of the valves is such that this never occurs during normal operation. However, it can occur if the timing belt breaks, slips or loses enough teeth to throw the valve timing out. It can also occur if the timing belt is replaced incorrectly (with the valve out of time) or possibly in the case of a broken valve spring that doesn't close its valve quickly enough.