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?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Constant knocking sound from engine

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: I hear a knocking sound coming from the engine.

Hi there. The sound could be the lifters sticking and not getting oil to them. This would be for the noise lessens as the rpm's goes up. Add 1 quart of ATF Type F to your engine oil and run...

Q: Whining noise at 35 MPH

Tires with abnormal wear can make noises going down the road. Defects, improper alignment angles, and broken suspension components can cause this damage to the tires. On another note, a failing wheel bearing is a part that shows its wear...

Q: Starting and shaking issues on a 2007 Honda accord.

Hi there. Check the alternator and see if it is making a full charge to the battery. If the vehicle is having a slow start when cranking, either the battery has lost a charge and is low or the starter...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
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.