Six Causes of a Knocking Engine

You are driving along, and your engine starts to knock. This has been happening a lot lately. Trinity Auto Care advises that most engines knock because there is a detonation problem in the engine. There are two other reasons why you may hear knocking sounds coming from your engine. We are going to discuss all of the causes of engine knock below.

1. Faulty Knock Sensor

Your car, truck, or utility vehicle’s engine is equipped with a sensor that is manufactured to detect when the engine starts to knock. Once this happens, the sensor alerts the engine control module so it can make adjustments in the combustion chamber to correct the knocking. If the knock sensor has gone bad, the engine control module will be unaware that the engine is knocking.

2. Lean Air/Fuel Mixture

If you have a fuel mixture in the combustion chamber that has too much air in it, you will end up with a knocking engine. Things that can cause a lean fuel mixture include a clogged fuel filter or injectors, a problem with the fuel pump, or a problem with the oxygen or mass airflow sensors.

3. Loose Accessory Belt

You may think that your engine is knocking but it actually isn’t if the accessory belt is loose. When this belt is not tight enough, it will slap around inside the engine and make it sound as if your engine is knocking. Tightening the belt or replacing the belt pulley generally resolves the problem.

4. Low Fuel Octane Rating

Another thing that can cause detonation knock in your engine is putting fuel with a lower octane rating than is recommended in your tank. This causes the fuel to detonate multiple times rather than just once. This is what creates the knocking sound that you hear coming from the engine.

5. Misfiring Spark Plugs

If your spark plugs are old and misfiring, this will make another detonation knocking sound. If the spark plugs are new, it’s possible that they are misfiring because you have a problem with the engine control module. This main computer chip controls when the spark plugs fire.

6. Worn Rod Bearings

Finally, worn rod bearings will make your engine knock because the pistons are clanking against the cylinder walls. The bearings control the rod motions, and if they are worn, the rods will not move the pistons up and down in a straightforward motion.

Trinity Auto Care is the best auto service shop in White Bear Lake, MN, and we are also the best auto service shop in Blaine, MN, so call us today if your engine is knocking.


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