Skip the auto shop - Our mechanics make house calls

Q: Constant knocking sound from engine

asked by on

My car makes a constant knocking/pinging sound which increases when the transmission is engaged, it consumes lot of fuel. It used up the engine oil just three weeks after servicing.

My car has 80000 miles.
My car has an automatic transmission.

Hello and thank you for contacting YourMechanic. The knocking sound is coming from the flex plate in the back of the engine. The flex plate is what drives the torque converter to the transmission. The flex plate is probably cracked or broken. This will make a constant knocking or pinging sound and gets louder when the transmission is engaged.

Your fuel consumption could be caused by the engine having to work harder to make up the power loss between the engine and transmission. I recommend having the flex plate replaced along with the torque converter.

Plus, you will want to check the front seal and the seals on the input shaft to the transmission for any damage. Usually soon after repairing a broken flex plate, the transmission front seal tends to leak. I recommend replacing the front seal when the transmission is out.

Before you replace any parts, I recommend seeking out a professional, preferably a YourMechanic professional to assist you with a thorough diagnosis of the noise coming from your engine.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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

Get a quote

What others are asking

Q: Knocking from front end.

This could be a lot of things from the sway bar links to the control arm bushings. I suggest you have your vehicle inspected and repaired by a trained professional, like one from YourMechanic. They will be able to hear...

Q: Odd noise when I turn at low speeds.

From what you've described your power steering pump is probably bad. You need to check the oil in it to make sure its not too low, however, I think it's already bad. Once you hear that noise there really isn't...

Q: Car sounds like old bed spring

Struts or any number of suspension components can cause a squeaking noise over bumps or when turning. Typically, components like ball joints can be the cause. In most modern vehicles, components like ball joints are greased and sealed at the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.