Timing Belts-Chains or Gears, all perform the same engine timing function. Their job is to synchronize the rotation of the crankshaft and camshaft. Despite having the same functionality, Timing Belts-Chains or Gears are unique in their design.
At first, engines used timing gears but slowly evolved to timing chains. Later, timing belts came around and were quieter, but, problematic. As a result, over the years broken timing belts have damaged many interference engines. Interference designs help engines breathe better; by improving engine efficiency, power, fuel economy and emissions.
More recently, engine have been moving back to stronger and longer lasting timing chains. As a result, preventing premature failure and damage of interference engines.
What Is the Difference Engine Timing Function Belts-Chains or Gears?
- Timing Belts are light and quiet, but they do not last long, relatively speaking. Oil and coolant leaks, speed up this deterioration. Most automakers recommend, replacing the timing belt every 60,000 to 105,000 miles.
- Timing Chains are heavier and more complex than timing belts, but they also last much longer. Really, unless there is a problem, timing chains do not have a replacement interval. Regular oil changes prevent premature wear, stretching, and failure.
- Timing Gears are the heaviest and noisiest, with a distinctive whining noise. Like timing chains, timing gears are strong, accurate and last a long time.
For decades, timing gears and timing chains were state-of-the-art, but noisy and heavy. Drivers demanded something quieter, so timing belts were born.
Timing Belts
As the belts are flexible and there is no metal-on-metal contact, it eliminates the need for lubrication. Most manufacturers recommend changing the timing belt, between 60,000 and 100,000 miles. All timing belts are fed through a series of pulleys and tensioners.
The tensioners, pulleys, and water pump will also wear and should be replaced. So, do the whole job at the same time, the timing belt, water pump, tensioner, and idler pulley. Because, if the timing belt fails, the other parts are not far behind.
Timing Chains
As an alternative to a belt, timing chains are seen to be a much more durable method of keeping an engine in time, as belts can last as little as 40,000 miles before they begin to wear and need replacing. And keeping an eye on your car’s mileage in relation to the timing belt is certainly not something that should ever be neglected. Over time, the belt can become slack (or over-tighten), teeth can be worn down or ping off during operation, all to potentially catastrophic effect.
All timing chains are made of metal and resemble the chains that are on bicycles. The chain runs through the inside the engine, so it can be lubricated by engine oil. Their main benefit is that they last for a long time. Some disadvantages of timing chains include the louder noise level and the damaging impact from one if it breaks.
Like timing belts, they are fed through a series of tensioners. Timing chain tensioners, rely on engine oil pressure. If for any reason the oil pressure is low the chain tensioners; can lose pressure and affect engine timing. This results in poor engine performance and the chain may, malfunction causing extensive damage. Most timing chains have no connection to the water pump, unlike timing belts.
Timing Gears
So, timing gears in some ways, are the easiest to explain. A gear on the front of the crankshaft turns a gear on the front of the camshaft. That is, it. Timing gears are almost always located on the front of the engine. And are lubricated by engine oil. They only need attention if one of the gears starts to wear; in which case replacement is the only repair.
Timing Belts and Chains Maintenance
Let us say your timing belt or chain jumps or even brakes; the camshafts will inevitably leave whichever valve was open at the time in its actuated position within the cylinder. This is particularly troublesome in an interference engine, where the pistons share their TDC with the same area that the valve extend to. The continued reciprocation of the pistons will then send a piston head crashing up into the opened valve, crushing it and therefore producing a potentially fatal bill once you are towed to the local garage.
To stop this ever happening, I would advise getting the timing belt changed immediately on any high-mileage car that you buy, unless there is blatant evidence that it has already been changed recently. The last thing you want to do is get a couple of thousand miles into ownership before the belt fails and you are left with a severely broken engine and a horrendous labor bill. In the case of timing gear, it really is better safe than sorry.
The aftermath of a snapped timing belt…
Timing chains on the other hand should never need to be replaced and are an integral part of the engine block, needing an oil supply to stay lubricated. Although a belt is cheaper to produce for the car manufacturers, changing them can be expensive depending on their placement.
Finally
So, your engine will use one of either a Timing Belts, Chain or Gears, depending on your car model. High displacement vehicles come with the timing chain; but most reasonably priced cars, have the timing belt. If your vehicle manufacturer recommends replacing the belt or chain at regular intervals, do it. Finally, the timing belt has the key advantage of being cheap but requires maintenance.
Hey Bob, I have a 1973 corvette that has a timing gear(very loud hummm). I was looking to replace it with a timing chain. My question to you is 1, would my timing chain be correct if other work was done to the motor? Like an oversized cam? 2, can I just remove the timing gear and bring it to Advanced auto parts and match it to a chain? Obviously I’m not a full fledged mechanic but I am eager to take on this task. Jim
Jim: If you are currently using a gear drive converting to a timing chain is certainly a DIY project, same with changing out a worn timing chain assembly. Also, with gear-drive timing there are 2 types of gear kits (1 noisy and 1 quiet) so it may just be the type of gear. I would suggest before you start any disassembly reach out to Summit or Jegs Performance Parts to determine which timing chain assembly is best for your current application (IE engine size, type of CAM, etc) as the local parts store does not have the proper expertise to match up the proper parts to your specific car. It is not wise to just change a gear or part of the timing gear or chain assembly as they work as a unit so getting the kit (including 2 gears and a chain is best). I hope this helps. Bob