Q: What will cause a motor to knock?

asked by on October 03, 2016

How do I fix this knocking noise?

My car has 18000 miles.
My car has an automatic transmission.

Noise from engine or exhaust Inspection $79.99 - $89.99 Get a Quote

Hi, thanks for writing in. Engine knock is typically caused by excessive clearance in the lower engine bearings (rod and main). Of course, to know for certain, a professional would need to listen to the noise firsthand. Spark knock, which is the result of abnormal combustion, can also result in a knocking or pinging noise. Loose torque converter bolts or a cracked flex plate can also do the same. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

Put my GMC into gear and when I give it gas it just wines and won't move.

Hi there. Check the clutch to see if it is slipping. When a clutch slips, the engine will continue to operate but the transmission will not drive under a load. If the clutch is new and the noise is still...

The best spark plug for Chevy Blazer

The best thing really--those things were designed for ACDelco plugs they came with. And if it didn’t come with the Radian spark plugs, buy the AC or Radian, because they last longest. Since spark plugs were designed for an engine,...

My 2010 Chevrolet Equinox has a timing chain replaced and I was wondering if the timing gear was part of this.

Hello. If they replaced the timing chain to begin with then they should have also replace the timing chain gears and the tensioners at the same time. If they did not replace all of these parts when then installed the...

Check engine light on, power loss in fourth gear

Many different faults can be attributed to your 2008 Chevrolet Aveo5's loss of power. In cases where the Check Engine Light has not set a hard code, it can be a bit harder to pinpoint the issue. If the...

My car makes a noise when it's cold

Hi there: This sound could be caused by the actual radiator fan being slightly bent, a drive pulley that's damaged or even the serpentine or drive belt that's wearing out. There are other issues that could be causing this problem,...

Whining when in gear - 2007 Dodge Nitro

The noise you are hearing is coming from the transmission and is most likely the internal bearings of the of the output shaft. You should have the problem verified by a mechanic and have fluids checked to be full in...

A rattle when first start up

G'day Brett: Without knowing exactly what type of Nissan you have, or being there to inspect the vehicle, it's hard to tell you why the engine is rattling when you start the vehicle. However, in most cases, the initial rattle...

Car says service stabilitrak and has a knocking noise.

The light could have come on for the brake fluid could be low and causing the system to see that the brakes are not safe. For the engine loosing power and making a knocking noise, there could be a misfire...

Problem with a wheel bearing.

A mechanic will have to check to see if you have a wheel bearing that is noisy when they test drive the vehicle. You are not specifying the front or rear bearing noises. The front is part of the front...

Related articles

A Buyer’s Guide to the 2012 Chevrolet Traverse
You You might not always need all of the cargo and passenger space available to you when you buy a 2012 Chevrolet Traverse, but it’s nice to know it’s there. This seven-passenger crossover utility vehicle (CUV) has tons of space...
Why Does My AC Rattle When I Turn It On?
Common reasons why a car AC system makes a rattling noise is due to a failing AC compressor, worn serpentine belt, or worn out AC compressor clutch.
A Buyer’s Guide to the 2012 Chevrolet Volt
Whether Whether you’re concerned about the environment or just want a vehicle that allows you to use less gas, the 2012 Chevrolet Volt might be just right for you. Designed to run entirely via an electric current, this electric hybrid...