How to Diagnose Common Engine Noises

by Jenelle Watson

You hear it out of the blue, that ticky-tacky, clicky-clacky, rat-a-tat-tat sound under the hood. Should you pull your car over and call for help, or is it safe to keep driving? Your ears have the answer.Knowing more about common engine noises and how to describe them may help you pinpoint a problem. It can also help you explain your concerns to your automotive technician. Here are some noises, as described by the experts from the Car Care Council, and a look at what may be causing them:

Do you hear what I hear?

You hear and feel a strong, dull rotational knock, especially when the engine is pulling. The knock occurs regularly at every other rotation. This may be caused by a loose main bearing.

You hear an irregular clicking sound. Fast idle the engine, then shut off the ignition. If you hear and feel a thud, you might have a loose fly wheel.

You hear a tinny knock that’s most noticeable upon deceleration but can also be heard with the engine idling. Your engine may have loose rod bearings.

You hear a clicking noise with a double knock that is loudest during idling. Causes can include a loose piston pin or inadequate oil. Clicking noises can also result from too much tappet clearance in a valve, or a hydraulic tappet is not working correctly. Clicking or tapping noises may also indicate a malfunctioning hydraulic lifter.

You hear a ticking noise. This may indicate a problem with the fuel pump. To diagnose, remove the fuel pump and put a plate over the hole. Run the engine with the fuel that’s left in the carburetor. If the noise stops, it was likely caused by the fuel pump.

You hear a ping or chatter, mostly during acceleration or when the engine is under load. This may indicate a spark plug problem

You hear a sharp rap at idle or higher speeds. This may indicate excessive crankshaft end play. The sound should disappear when the clutch is disengaged.

Tip

  • check Some clicking or knocking is normal when the engine is cold but should disappear as the engine warms.

Warning

  • close Some engine noises indicate only minor problems. Others signal the need for major repairs. If you hear an unusual engine noise, don’t wait; visit your local repair shop for a diagnosis.

About the Author

Jenelle Watson has written about business and consumer issues since 1990. A magazine editor and former newspaper editor, she is an avid gardener and design enthusiast with more than 25 years of successful projects under her toolbelt. She and her husband have three children.