Six Reasons Why You Hear Knocking Sounds Coming From the Engine

You should never hear knocking sounds coming from your car, truck, or C/SUV’s engine. If you do, drive straight to Pit Shop Auto Repair. There is either a detonation problem that is making the engine knock, a rod and rod bearing problem that is making the engine knock, or a problem with the accessory belt. Let’s talk about all of these things below.

1. Faulty Knock Sensor

The engine is equipped with a knock sensor. This sensor tells the engine control unit or ECU that the engine is knocking. This gives the ECU a chance to see if it can fix the problem by itself to stop the engine from knocking. If the knock sensor is malfunctioning, it may not communicate with the ECU.

2. Lean Air/Fuel Mix

For example, one thing that will make the engine knock that the ECU can fix is a lean air/fuel mixture in the combustion chamber. This mixture has too much air in it and the ECU can add fuel to it to balance it out. This can stop the detonation knock that is going on inside of the cylinders.

3. Low Octane Rating

Another thing that can cause detonation knock is fuel that has a lower octane rating than your engine needs. For example, you cannot put fuel with an octane rating of 87 into a high-performance engine. This will cause multiple detonations in the cylinders, i.e., the knocking sound.

4. Worn Spark Plugs

Worn spark plugs can also cause multiple detonations in the cylinders. The misfiring plugs can also make your engine stall frequently. Replacing the plugs will prevent the multiple detonations. If the plugs are fine, the ECU may be malfunctioning and firing the plugs out of order.

5. Worn Rod Bearings

All of the above is what is considered detonation knock. Rod knock happens when the rod bearings wear out and cause the pistons to crash inside the cylinder walls. This banging is the knocking sound that you hear, and it can seriously damage your cylinder block.

6. Loose Accessory Belt

Finally, your engine may not be knocking at all. The noise that you hear could be the accessory belt if it is too loose. When the belt is too loose, it will slap against its pulley and other auto parts. We can stop the knocking noise by tightening the belt or replacing it.

Call Pit Shop Auto Repair in Libertyville, IL, today if your engine is making a knocking sound. It’s important that we find the source of the problem and repair it immediately to avoid engine damage.