SMART Advice: Check The Timing Belt On Your Car

If you own a motor vehicle please consider this question, “Does its engine have a timing belt, or a timing chain?” If your response is, “I don’t know,” that is quite normal. However, I hope you did not include, “…and quite honestly I don’t care.” If it did, please stop for five minutes to read this article as your bank account could benefit from the information that follows.

What Is Engine Timing?

Two types of timing occur in an engine. First, consider spark timing, wherein an electrical impulse is sent to a spark plug so as to ignite the fuel/air mixture at just the right time. Secondly, there is valve timing which involves opening and closing valves in each cylinder to control the flow of air, fuel and exhaust gases. When the valves do not open or close at just the right time problems can occur: engine power and fuel economy are decreased; an engine could be severely damaged if a piston collides with a valve which is sticking into the cylinder. The process of valve timing is controlled either by a timing belt or a timing chain.


A timing belt is not the same as a serpentine belt; they are significantly different so don’t confuse the two.

The serpentine belt drives accessories like a water pump, alternator or power steering pump; it is externally visible and easily replaceable. A broken serpentine belt will cause the accessories to stop turning without harming the engine.

A timing belt is totally different; it is internal, hidden behind a protective cover.

The Differences Between Belt And Chain

A brief comparison can help one understand the differences between a timing belt and timing chain.

Timing Belt

  • Made of rubber—same material as a fan belt; not very durable
  • Manufacturer intends it to be replaced around every 70,000 miles

Timing Chain

  • Steel links held together with steel pins, like a bicycle chain on steroids; very durable
  • Designed to last the life of the engine, usually 250,000 miles or more

As a timing belt does its job the rubber will slowly deteriorate. At around 100,000 miles it will have weakened allowing for the possibility that it could slip or even break; this will allow a valve to remain stuck open. A moving piston which collides with an open valve can easily inflict $1000—or more—damage to the engine. In some cases it can render the engine irreparable.

What To Do

First, identify which engine is in your vehicle: gas or diesel? Now, what size is your engine? Raising the hood and looking at the engine might give you the answer. Often it is displayed using a couple of large numbers like 2.4L, 3.6L, 4.2L, etc.

Secondly, find out if your particular engine has a timing chain or timing belt by checking a service manual or through an internet search. If yours has a timing belt and you don’t know when/or if it was replaced you really should make plans to replace it in the foreseeable future. Choosing to wait until it breaks could end up being a very costly decision on your part.

One final thought, timing belts are not expensive; $50 on average. However, to properly replace one requires meticulous attention to detail. If the internal engine timing is not properly aligned when replacing the parts the engine could suffer serious damage the first time it gets started. The task really ought not to be trusted to a mechanic who has marginal skills.

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