Toyowest Automotive

Timing Belts

What are they? What do they do? What's the big deal about about them anyway?



Timing belts keep the valves from colliding with the pistons. They synchronize the opening and closing of the intake and exhaust valves with the upward & downward motion of the pistons to work in perfect harmony so that the engine can run and produce power which is the foundation for all other systems to function correctly. Systems such as; fuel, electrical as well as the on board diagnostic system. Timing belts are typically made of rubber with nylon synthetic reinforced cords and as time and mileage increase the timing belt will fatigue in various forms such as stretching cracking & fraying.


Stretching is very normal as mileage and time go on because of its nature. Cracking & fraying may be due to excessive heat from either a worn stretched belt causing the belt to slap around pulleys rather than being tight and driving the pulleys. Fraying may be due to an old worn belt coming apart or possibly a seizing pulley or water pump getting ready to fail. A worn or loose timing belt is very dangerous in terms of the damage it leaves behind after it breaks or jumps a tooth or two on a sprocket. When the timing belt decides to fail it will be catastrophic. Today's high tech engines are designed to produce maximum power provide the best performance & fuel economy while producing very little tail pipe emissions.

Manufacturers achieve this by producing small high output high compression engines with multivalve valves, camshafts variable valve timing all working in harmony because of the timing belt synchronizing them all together. Manufacturers also have their recommended replacement interval usually based on time or mileage whichever comes first. These recommendations are only meant to be used as a guide only! Everyone drives differently. Where you drive? How you drive? What you drive all are determining factors when replacing a timing belt.

 For example the harsh hot weather in the Southwest destroys anything that’s rubber the dry heat dries out and crystalizes rubber making brittle weak and vulnerable to failure. This type of driving condition is very severe and very hard on vehicles whereas the cool damp climate of the Northeast is very mild on rubber components. Replacing the timing belt should be done between 5-6 years or between 60-90 miles whichever comes first. One important thing to understand when having the timing belt replaced is it's rarely just replacement of the timing belt only!


 That’s because there are other parts associated with timing belts function that must be inspected to ensure lone trouble free operation. For example; most water pumps are driven by the timing belt these are prone to leakage and bearing failure as mileage increases replacing it while the timing belt is removed is very common practice.


There are idler bearings and tensioner bearings that become overheated due to stretched belts slapping against them causing the outer surface of the belt to melt to the pulleys. There are also various different seals that are hidden behind the timing belt pulleys that are prone to leakage allowing oil to saturate and ruin the belt.

All of these components must be inspected by feel as well visually and audibly for proper function and replaced if needed to ensure smooth trouble free operation of the timing belt. A competent experienced professional understands the importance of everything working together. Our goal is to save you time money and stress by using better methods when it comes to maintaining your vehicle. By Inspecting and identifying worn components associated with any service or repair and replacing them when needed allows us to better serve you by doing it once and doing it right.