10 Reasons Why Your Car Shakes when Idle

Tim Jumah
By Tim Jumah Cars 2

Every driver has faced this situation at least once. The car is in idle mode, but it’s shaking. That’s why many people are wondering why a car jerks when idle? Is this normal or something a professional mechanic should pay that attention to?

Well, there are many reasons a car shakes when you idle, and we will talk about 10 of them in this article.

If you’re having this problem, it’s most likely because the mounts are wearing out, which causes them to lose their stiffness, so your engine moves around and may even vibrate.

10 Reasons Your Car Shakes when Idle.

1. Motor Mounts

A worn-out, broken, or weak motor mount can make a car shake when idle because it cannot hold up the engine properly, making it move from its regular position with every gear you go into, making your car shake. The same thing happens with driving on really bumpy roads.

If the motor mount is worn out, you can hear how it knocks or clunks when speeding up or decelerating slowly.

A regular tune-up should solve any problems you might have with a wrong or faulty motor mount, so if this is the case, you should have a mechanic look at it.

2. Loose or broken engine mounts

Last but not least, your car might shake when idle due to losing or broken engine mounts.

If your car shakes at idle and there’s no clicking noise, it’s probably the engine mounts

if you’re having this problem, it’s most likely because the mounts holding the engine are worn out, which causes your engine to move around and maybe even vibrate.

Replacing all of them is expensive, but if you notice your car shaking when idle, the first thing to check is your engine mounts because they can wear out, which causes them to lose their stiffness over time.

3. Vibration dampener

Another reason that may cause your car to shake when idle is a missing or broken vibration dampener.

The vibration dampener reduces the shaking and uneasiness inside the car by balancing out the forces entering it through your engine, mainly unbalanced rotating components like crankshafts and pistons, which cause vibrations when they work.

When this part isn’t working correctly or is entirely missing, your engine will shake at idle.

Usually, a broken vibration dampener is related to an oil leak coming from the engine, so if you have a car that shakes at idle and you see oily stains or smoke under it when it’s running, this means your car probably has a broken vibration dampener.

Also read, Signs You Need New Brakes for Your Car.

4. Worn our or dirty Spark plug

The spark plug is another possible reason why your car shakes when idle.

If the spark plug is worn out, it won’t generate enough electricity needed to produce a vital spark, so this will cause misfires which means the car shakes.

Replacing the spark plug is an easy fix, so if your car shakes at idle, check the spark plugs to see what’s wrong.

5. Faulty or Dirty Fuel intake system

When the fuel intake system is faulty or dirty, this can cause your car to shake when it’s idling because there will be problems with the air-to-fuel mixture.

This usually happens with cars using carburetors instead of fuel injection systems nowadays.

The main parts you should check if your car shakes when idle are the fuel filters and the air filter.

6. Worn out or clogged injectors

When there’s a problem with your car shaking when idle, an engine is caused mainly by dirty or worn-out injectors.

If they’re dirty, it affects the way they spray and atomizes the fuel, and also, if they’re worn out, the car will shake because there’s no fuel being injected into your engine.

A common reason your injectors become dirty is bad quality fuel or petrol stations that don’t have excellent quality fuel, which means it has too much sulfur.

If your car shakes when idle after filling up with a new tank idle, it’s possibly because the fuel you’re using has too much sulfur in it.

7. Disconnected, broken, or loose hoses

Car hoses are another possible reason that can make your car shake when idle.

The most common hose that disconnects or falls off is the vacuum hose, usually because it’s old and brittle, so this will cause the engine to suck air instead of pulling fuel in, which makes it shake at idle.

If your car starts to shake immediately after refueling, look underneath it to see if any hoses are disconnected because this can be the cause.

Another reason your car shakes at idle could be that your PCV valve or breather hose is missing, which means your car’s not getting enough air to make it vibrate.

Read also, 10 Most Reliable Cars in Kenya

8. Poorly adjusted timing belt

If your car’s shaking when it idles, the most common reason for this is a poor timing belt adjustment.

Your engine has multiple valves that open and close to let fuel in or exhaust out, which are timed by the camshafts. So, if they’re not adjusted properly, this will cause your car to shake at idle because the valves will open and close at the wrong time.

To know if your car might have these problems, look under it while the engine is running.

If you see any valve train components that aren’t moving or are shaking very badly, this means they’re not correctly adjusted, so it’s possible to be the cause for your car to shake when idle.

9. Worn out engine bearings

Another possible reason your engine shakes when idle is due to a worn-out bearing, but this usually affects older cars with high mileage on their engines.

A regular tune-up should solve any problems you might have with a bad or faulty engine bearing, so if this is the case, you should have a mechanic look at it.

10. Seized or damaged piston rings

Another possible reason your engine might shake when idle could be due to seized or damaged piston rings.

When the engine gets hot from running for long periods, the oil residue will start to gum up and get sticky, so when you turn your engine off, this residue will stay in the piston’s cylinder bore.

If this is the case, you can have it fixed by having a mechanic look at it to replace the broken or damaged piston rings and clean out the residue, which should solve the problem.


In summary, you need to get a professional opinion or perform a complete car diagnosis to get the most accurate results. Still, in general, if your car shakes when idle, it could be caused by any of these problems.

Now that you’ve read this article, you know the ten reasons a car shakes when idling are and how to solve them.

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Jumah has been a content writer for business and technology topics since early 2019. He has experience in writing and marketing and is dedicated to creating informative and engaging content.