6 Engine Knock Causes That Shouldn’t Be Ignored

An engine knock can usually be attributed to a detonation problem, which is why the knocks shouldn’t be ignored. Bad engine detonation can cause catastrophic engine failure if the problem is left unchecked. Techway Automotive can inspect your engine and find the cause of your engine knock. Here are six common reasons why an engine will make knocking sounds while idling or while in motion.

1. Detonation Timing Issue

Fuel injectors spray gas into each cylinder where it’s mixed with air and set on fire by the spark plugs. This creates combustion, which your engine uses to start and run. If spark plugs aren’t firing in the right order – bad timing – there could be multiple detonations that make knocking sounds in the cylinders.

2. Air/Fuel Mix Issue

If there is too much air in the mixture, the detonations will also multiply and knock in the cylinders. The combustion mixture must have enough gas in it to fire up and burn quickly. Excess air slows down combustion and can be caused by clogs in the fuel system or incorrect air-to-fuel ratio measurements.

3. Knock Sensor Issue

Your vehicle has an engine control unit (ECU) and knock sensor to ensure the timing and detonation are correct at all times. If the ECU or knock sensor is going bad, they will not be able to process the data from the combustion chamber and correct any detonation issues. This can make your engine knock.

4. Rod Bearing Issue

Worn rod bearings can pretty much kill an engine for good. Rod engine knock is caused when the rod bearings are worn and they cannot support the pistons in the crankshaft any longer. The sound you hear is the pistons knocking against the crankshaft walls and this can lead to devastating engine damage.

5. Belt Accessory Issue

Your vehicle’s accessories are powered by a belt and series of pulleys that run through your engine. If the belt stretches or any of the pulleys get bent or damaged, you might hear knocking sounds coming from the engine. This sound is coming from the belt, the tensioner, or a damaged accessory pulley.

6. Fuel Octane Issue

Finally, you know how we talked about multiple detonations in the cylinders above? Well, the wrong octane in your engine can also make this happen. High-octane fuel, such as 91, burns faster than low-octane gasoline. Make sure to put the right octane in your engine to avoid unnecessary engine knocking.

Call Techway Automotive in Dothan, AL, or our shop in Blakely, GA, if your engine knocks. We’ll find out why you hear the annoying sound and fix it.