8 Reasons Why Your Car Engine is Making a Rattling Noise


If your car engine is making a rattling noise, there is something wrong with your vehicle. An engine should always sound smooth. If your engine starts making a rattling noise, here are 8 reasons why it is doing that:

If your car engine is making a rattling noise on startup, idle or when accelerating you could have a faulty serpentine belt tensioner , a loose bolt on the mounting bracket, loose timing belt, rusty or broken flexplate, faulty harmonic balancer, loose fan blade, engine knock(pinging) or low levels of engine oil.

8 Reasons Why Your Car Engine Making a Rattling Noise

An car engine has to make some kind of noises. The engine has many moving parts which all make some kind of noise. But all of this is normal. However, if your engine starts making a rattling noise, that is far from normal. Here are the top 8 reasons why your car engine is making a rattling noise:

1. Low Engine Oil

8 Reasons Why Your Car Engine Making a Rattling Noise - Low Engine Oil

If your engine is making a rattling noise, the first thing to suspect is low engine oil. If your engine has low oil, it can cause rattling sounds due to poor or no lubrication for vinyl engine components. Check engine oil level and add if needed. If the engine oil level is really low and the engine is rattling after the oil has been added, permanent damage could have occurred and replacement is needed for whichever part is been damaged.

You can easily top up your engine oil.

2. Cracked or Broken Serpentine Belt

8 Reasons Why Your Car Engine Making a Rattling Noise - Broken or Cracked Serpentine Belt

All diesel or gasoline cars have a serpentine belt. Some have one, some have two or three. The serpentine belt has a function to drive your alternator, water pump and air conditioner compressor. Very often the serpentine belt is mistaken for a timing belt. The difference is that the timing belt runs the engine camshaft and in most cases you cannot see it because it is hidden under protective covers, whereas the serpentine belt is visible.

If the serpentine belt breaks, your engine would start making rattling noise. The car won’t be drive-able and you would have to call a towing truck. If you drive your car with a broken serpentine belt, the engine would overheat because the water pump won’t work.

If this is the case, you can get a new one on amazon.com

3. Broken Mounting Bracket

8 Reasons Why Your Car Engine Making a Rattling Noise - Broken Mounting Bracket

The third thing that could be making an rattling noise is an broken mounting bracket. Mounting brackets are used to support various accessories such as the power steering pump compressor and air pump, as well as to attach the engine to the vehicle frame.

If one of these mounting brackets is broken, the component that the bracket is holding it will start to vibrate and make a rattling noise. You would need to check every mounting bracket nut or bolt to make sure that there is nothing loose. If you wish to learn more about parts of car, their function and location, click here.

4. Broken or Cracked Timing Belt

8 Reasons Why Your Car Engine Making a Rattling Noise - Broken or Cracked Timing Belt

The timing belt has a function to connect the engine crankshaft to the camshaft which allows the valves to open and close at a correct timing with the position of the pistons. The timing belt has to be under certain tension which is allowed by a timing belt tensioner.

If the timing belt or the timing belt tensioner gets damaged, it will get loose and will start to vibrate and make a rattling noise. You must always change your timing belt if you notice any cracks to avoid any additional damage to the engine.

5. Broken Flexplate

The flexplate or a flex-shock device is found in cars with automatic transmissions and have a function to connect the crankshaft to the torque converter and improve smooth running.

If your vehicle has a broken flexplate, the connection between the crankshaft and the torque converter would be compromised and it won’t run smoothly. The flexplate will start to wobble and will most definitely produce rattling noise. If this is the case, you would have to remove the flexplate cover and check for rust, cracks or missing bolts.

6. Broken Crankshaft Harmonic Balancer

The crankshaft harmonic balancer is part of the crankshaft which has a function to absorb and reduce vibrations from the engine as the crankshaft rotates. It is made of rubber and metal and can be found at the front of the crankshaft pulley.

If the rubber and metal on the crankshaft harmonic balancer wears or gets dislodged it would make an rattling noise and cause engine vibrations. It is an expendable item and at some point of time it would fail.

7. Faulty Fan Clutch

8 Reasons Why Your Car Engine Making a Rattling Noise - Faulty Fan Clutch

Fan clutch is a component of the cooling system that regulates the engine temperature by engaging and disengaging the engine cooling fans. Some vehicles have mechanic fans, some had electric fans, but they both operate based off engine temperature. Once the engine temperature gets high, the thermostat triggers the fan clutch which engages the cooling fans.

If the fan clutch is faulty and gets stuck in an engaged position, it will turn on the engine fans even when they are not needed which will create a loud noise. If the cooling fans run for a longer period of time, they can get loose and start creating a rattling noise. Open up the hood and inspect the fan blades by checking for excessive movements.

8. Car Engine Knock or ”Pinging”

Engine Knocking or Pinging

A engine knock or pinging occurs when the mixture of air and fuel inside a cylinder is incorrect or unbalanced which makes the fuel burn unevenly causing shock waves at wrong times which is making a rattling noise and can damage the cylinder wall or the pistons.

Basically when an uncontrolled explosion happens in the cylinder it can sound like an audible rattle. Most cars have knock sensors that control this condition. But, if the fuel octane levels are too low it will persist anyways. If the problem keeps happening, the engine could have carbon buildup.

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Content