What is up engine heads, today we will be taking a detailed look at timing belts and timing chains. We will compare one with the other and dive deep into the benefits and drawbacks of both of these critical engine components all while presenting objective facts on both of these.
So what does a timing belt or a timing chain actually do? Well the key word here is “timing” and timing in this case refers to the relationship between your pistons and your camshafts and valves.
For an engine to run properly this relationship must be constant and maintained at all times. Chains are more resistant to wear because of course metal resists wear better than rubber. But there’s a catch. Metal resists wear well only when it’s lubricated and this brings us to our first big difference between timing chains and belts. Belts run dry but chains are splash lubricated by the oil in your engine. This means that chains must be sealed away from the environment to prevent oil leaks.
The easiest way to tell if your engine has a belt or chain is to look at the engine. If it has plastic covers on the front, it’s likely running a timing belt, if it has a sealed metal cover than it’s likely running a chain. Because they are more durable timing chains have much longer service intervals than belts, some chains don’t even have service intervals. They last the life of the engine.
Even if you don’t use the engine at all, a belt should be replaced after 6-10 years, depending on the engine. This is because rubber naturally deteriorates and degrades with time. Timing belts are sensitive to oil and coolant spills, which can significantly shorten their life.
High temperatures also contribute to increased rubber wear. A typical modern timing belt needs to be replaced every 60.000 – 100.000 miles. When timing chains do have service intervals, they are need to be replaced every 80.000 – 120.000 miles. While timing belts are generally the same and don’t differ much in terms of their design, timing chains come in two main different types – the silent chain and the roller chain.
Silent chains minimize the amount of noise created by chain and sprocket assembly. Silent chains are very common in engines and are loved by manufacturers because they are simple and cheap to manufacture. They are constructed from multiple links connected together by pins.
The profile of the links fits the profile of the teeth of the sprocket and voila the chain turns the sprockets. On the other hand roller chains incorporate rollers instead of links. The sprocket teeth fits in between the rollers and the rollers roll on the teeth as the chain rotates the sprocket. This both reduces friction and helps spread loads more evenly which also reduces localized wear.
Roller chains can be of a dual or single type and as you’re probably guessing dual rollers are more durable but due the increased surface area they also create more friction. The drawback of roller chains is that they are noisier when compared to silent chains and that they are also more sensitive to debris and contaminants in engine oil.
The first ever engine with a rubber toothed belt was racing car built by Bill Devin in the early 50s. It was a Frankenstein engine that used two Norton Manx cylinders on a Panhard crankcase and an overhead cam layout.
The first ever mass produced car to feature a timing belt engine was the West German 1962 Glas 1004. In 1966 Fiat also introduced the first twin cam engine driven by a rubber toothed belt and in the same year the United States got their first belt driven engine in the form of Pontiac’s overhead straight six engine.
So does this mean that belts are the better choice and that you should choose and engine with a belt instead? No, it simply means that the demands put on today’s engines have equalized belt and chain statistics and that some of the good reputation chains had doesn’t apply anymore.
The reality is that both engine drive systems are equally good provided you maintain your engine and replace components with quality ones when needed. What’s more important than belt or chain is maintenance as well as research.
Before buying a car with a certain engine, make sure to do your research well and get acquainted with the engine’s weak spots so you know what too look out for inspecting the vehicle and can accurately predict realistic maintenance cost that best suit your budget, needs and preferences.
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