One thing that can make it sound as if your engine is knocking is a loose accessory belt. This is because the belt slaps around inside the engine. Scotty’s Automotive can replace or tighten your accessory belt if it needs it or repair the cause of the actual engine knock. Let’s talk about the things that make an engine knock below.
Malfunctioning Sensor
Your engine has a sensor in it that is manufactured to detect when the engine is knocking. It notifies the engine control module that there is a problem so the module can make adjustments in the combustion chamber to hopefully stop the knock. If the knock sensor is malfunctioning, it may fail to alert the combustion chamber that the engine is knocking. Consequently, your engine will continue to knock.
Lean Air/Fuel Mixture
One of the things that the engine control module does to stop the engine from knocking is to correct a lean air/fuel mixture. This is a fuel mixture that has too much air in it. This lean mixture can make your engine knock because instead of just having one detonation in each cylinder, the extra air will cause excess detonations in each cylinder. These detonations are the knocking sound that you hear.
Worn Spark Plugs/Wires
It may be time for a tune-up if the engine is knocking. Worn spark plugs and plug wires can misfire and cause the engine to knock. As with the lean fuel mixture, the knocking sounds that you hear are multiple detonations in the cylinders. If your spark plugs are relatively new and are still misfiring, it’s possible that your engine control module needs to be replaced because it fires the plugs in a specific order.
Low-Octane Gasoline
Another thing that will create the multiple detonations in the cylinders is gasoline that has a lower octane rating than the rating that is recommended for your vehicle’s engine. In other words, you cannot put fuel with an octane rating of 89 in an engine that requires fuel with an octane rating of 91.
Worn Rod Bearings
Finally, the knocking sound that you hear coming from the engine could be the sound of the cylinder block being damaged. Rod bearings move the rods to which the pistons are attached up and down inside the cylinder walls. Worn bearings will cause the rods to jiggle and slam the pistons against the cylinder walls.
Call Scotty’s Automotive in Montague, NJ, to schedule an appointment for an engine inspection if your vehicle’s engine is knocking all the time.
