Timing belts are a common component of all internal combustion engines, used to maintain the synchronization between the crankshaft and camshaft. As such, an engine’s timing belt plays an important role in its operation. A timing belt is required in all modern automobiles, and is designed to withstand the heat and pressure exerted on it. However, it is not infallible. The belt’s ability to withstand these conditions deteriorates over time. A vehicle’s owner must therefore be aware of when a correas dentadas replacement should take place.
When to replace a timing belt
The lubricating ability of any component can be measured by using the “Stiffness Factor” (S.F.) method, in which the component is free-hand-tested on a frequency range between 0.5Hz and 10 Hz at 50% of its working temperature. The S.F. value is calculated by the following formula:
S.F. = (Max. amplitude – Min. amplitude)/(Max. velocity – Min. velocity) x 100%
The timing belt’s ability to withstand stress can also be measured using the “Ultimate Tensile Strength” (UTS) method, in which a tensile strength of 1200-1300 N/mm is possible before breaking; however, this value greatly varies depending on time and amount of use. This value is also altered by temperature. To determine the timing belt’s age, the age of its last replacement can be estimated. A replacement after 1,500 miles is indicative that it has reached its end-of-life.
Therefore, when replacing a timing belt, all components in the engine should be replaced at the same time to minimize heat affected metal (HAZ). When replacing a timing belt, white metal fragments are usually found in coolant and oil; however, these fragments may not affect the engine’s performance at all.
How to replace a timing belt
The process of replacing a timing belt will vary depending on the type of vehicle and the number of cylinders in it. Typically, timing belts are replaced at the same times as other engine components, and should be done by an automotive technician with engine training. A regular shop will charge lower prices for timing belt replacement however, they may not have the right tools or training to do so correctly. Furthermore, replacing a timing belt incorrectly can result in severe engine failure. Therefore, shops offering timing belt replacement should be selected with caution.
Determining when a timing belt should be replaced
Timing belts require periodic replacement for the following reasons:
- Wear and tear. Over time, the tension on a timing belt weakens, causing excessive play in the crankshaft’s long shafts. The belt will then wear and tear, leading to the timing belt breaking.
- Excessive heat on the timing belt can cause it to warp or crack. It will also lose lubricant oil, causing its stiffness to decrease and start to fail.
- Variations in crankshaft rotation speed can cause burn-in of the crankshaft and camshafts; this is another sign of impending failure of the timing belt.