Causes of Engine Knocks

You may have heard that someone's car had an engine knock, but you do not know what that meant. Read on and learn the major causes of an engine knock.

An engine knock refers to the "ping" or "knocking" sound that you hear when the air/fuel mixture combusts at the wrong time. That knocking sound happens because the mixture ignited without the ignition being set off by the spark plugs in the car engine. Several factors cause this problem.

Use of Low Quality Fuel

One reason why you should be particular about where you get the fuel for your car is that you will be protecting the engine from suffering from an engine knock. That fuel will ignite on its own once it reaches its compression threshold. Low quality fuel has a low octane rating and that is why it will ignite before the spark plug ignites it. If you are not sure what kind of fuel your car should take, contact a service station specific to your car's manufacturer--for example, contact a Renault service station near you for advice if you have a Renault so that you avoid an engine knock.

Use of the Wrong Spark Plugs

Each car has a particular kind/specification of spark plugs that it should use. Some people install the wrong plugs out of ignorance or in a bid to save some money when they replace worn spark plugs. How can wrong spark plugs cause an engine knock? The spark plugs may occupy more space within the combustion chamber. This will reduce the space available to compress the fuel/air mixture so it will ignite spontaneously before the plugs trigger that ignition. The wrong spark plugs can also increase or lower the operating temperature within the combustion chamber and that will affect the timing of ignition in that engine. For instance, oversized spark plugs may lead to higher operating temperatures within the chamber. That high temperature will cause the fuel/air mixture to ignite on its own.

Deposits Inside the Combustion Cylinder

These deposits can build-up due to several factors. One factor is that worn plugs can no longer ignite a fuel/air mixture completely so particles form on the cylinder walls when fuel is not burnt fully. Poor quality fuel can also have contaminants that coat the cylinder walls. All these factors combine to reduce the available space for air to mix with fuel. This results in an engine knock.

Always service your car at the recommended intervals so that you get advice about any problems that may be developing. For instance, the service technician may notice that the check engine light in your car is on. You may be advised to use higher quality fuel when he/she investigates the problem and connects it to an overburdened fuel system.