Rattling Engine

Hi! My husband owns a 2004 Honda Civic. It’s been a nice little car, but recently (about a month ago) he purchased a truck that he likes better, so it’s been sitting under our carport. He’s started it once or twice, but that’s about it. Yesterday we decided to sell it, put up an ad, and were promptly deluged with offers! Very gratifying, but today when he decided to take it out for a test spin, he heard a knocking noise under the hood. It only happens when the car is moving - not when it’s idling - and it speeds up and slows down with the speed of the car. He’s driven it around the block a couple of times, and it hasn’t gone away. He’s afraid it means the engine is bad. Are we in big trouble? Should we cancel the sale?

thanks for your help!

Chances are that a hydraulic tappet is sticking. He could try running some oil system cleaner through the engine. There’re various brands available at the parts store for a few bucks. Follow the directions to the letter.

Post back with your results.

Look under for anything on rims and check axles which should be covered with rubber boot but inside axle turns and if something get on or in them it could make noise
This is just something that is easy and free to check.

Do The Brakes Work Smoothly Without The Pedal Pulsing ?

Rust can accumulate on brake rotors and brake drums on cars that are parked for a while. This can make several different noises, including grinding and even a knocking sound.

Parking for a month should not cause an engine to go bad. You did check all under-hood fluids for quantity, right ?


Get the oil and filter changed on the car, first and foremost.
Then take it for a 50 mile drive on the highway.

Chances are the noise will stop after that.

My friend’s Civic of the same vintage did the same thing after sitting all summer while he commuted on his motorcycle.

You could always pop the hood, locate the sound of the knock, take a picture of the area its coming from, and post that for us. We would then be abel to tell you what the part is, and what to do.

And yes, people always want good Civics.
Let as many people see the car as you can deal with, and get several offers for it.


Hi everybody, and thanks so much for your help! We took your advice and drove it awhile, and the knocking stopped. But we decided to take it to a mechanic anyway - get a clean bill of health before selling! - and so the prize goes to those who guess the brake rotors! They were a little bit stuck, and that caused the noise. Thank you all so much for your help!

You’re very welcome. Thanks for the update.

Happy motoring.

Thanks. I’ll Take That Prize (I Seldom Win). I Was “Those” Who Guessed Brake Rotors. Aw Shucks, It Was Just A Case Of Giving A Common Sense Answer (Lucky Guess)! You’re Welcome !

Bladecutter gave excellent advice about driving it and “Chances are the noise will stop after that.” I’ll share the prize with him.


Corn muffins for everyone.