I have a 1996 5-Speed Manual Civic DX Hatchback that I bought new and have always taken very good care. I just had $1000 worth of work done in November (replaced the clutch, ball joint, exhaust manifold), which supposedly brought the car back to "like new" condition, and then a month later this new noise started up.

It's a little difficult to describe exactly what I'm hearing, but it's sort of sounds like a light metallic tapping, like a small pebble hitting the inside of a metal pot. At first I thought it might have something to do with the new clutch because sometimes it would happen right after I shifted and released it, but it was hard to tell exactly what the source was due to the initial intermittent nature of the problem. Then right around Christmas, I noticed that the sound was happening every time I stepped on the gas pedal, even when I wasn't changing gears. It doesn't seem to affect my shifting or acceleration but the sound drives me crazy and it feels like the car is running lousy. Any idea what it might be?

 

Someone suggested that it might be the heat shield or a loose part rattling around hitting something but I don't hear the noise when I go over bumps or when the car shakes, so I don't think that's the problem. It only happens when I step on the gas pedal and it's now gotten to the point where I can make the sound happen whenever I to want just by stepping on the gas, almost like a drummer kicking a bass drum pedal!

I listened to it again today real closely and the best way I can describe it is that right when I step on the gas pedal it sounds like a small object is lightly flung against the inside of a hollow sheet metal pan, which makes me think that it could be in the exhaust system somewhere. Sometimes it will hit twice in a row but it's always right after I step on the gas. It's hard to tell exactly where but the sound appears to be coming from the middle of the car right under the stick shift. I also hear the same type of noise when I start the car and when I'm shifting so then I think it might also have something to do with the transmission. I just don't know!

 

Could be a bad motor mount, though that's usually more of a heavy banging noise. Really I think it's just the heat shield, as you describe sort of a "tinny" noise directly under the center of the car. When you start or accelerate, the engine and exhaust pipe move slightly and that could be allowing it to rattle.

 

But the sound is so precise and unvarying, as if it is directly connected to the action of pressing down the gas pedal. If it was the heat shield rattling the sound would be more irregular and it would happen at other times, not just when I step on the gas.

 

Does pressing the clutch pedal down prevent the noise?

 

might sound crazy, but i lost the bolts out of the bracket that holds the throttle cable to the intake manifold. it was "tinking" before they finally came out while i was going down the road. worth a check anyway...

 

Do I still hear the noise if the clutch is depressed when I step on the gas? I will check that out this morning.

So maybe the throttle cable is snapping against the intake manifold whenever I step on the gas? I will look into that this morning also - thanks!

 

Strangest thing - sometime within the past two weeks the "clucking" sound completely disappeared. It just went away! Even if it's very quiet I still can't hear anything like I described earlier. The overall engine noise is maybe a little louder than normal but there is no more clicking, clacking, or clucking!

Since the first of the year we've been having temperatures in the single digits and down below zero so that might have something to do with it or maybe whatever was loose and flapping around down there finally broke off.

I'm still going to bring it to my mechanic but I'm not in as much of a rush as I was before. Does this new info help any with the diagnosis?

 

The way you said it sounds like a small pebble hitting a metal pan made me think. Inside your catalytic converter is a honeycomb shaped thing (to be honest idk what the heck it is haha) ive had that stuff break loose and crumble up in there. Couldve been that making the noise. Just an idea.