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05' Civic HX and ratling sound above 1,800 RPM

Hello everyone!

05’ Civic HX 5 speed with 167K. I picked up the car two years ago with 134K on the OD, and the only service records were regular oil changes.

Did: Timing belt; Valve job; Brake job. Both dealer and tire shop have gone over it / safety checked it twice.

About 10K miles ago it developed a racket (rotational noise, as if something was coming apart.) above 1,800RPM. “Can hear from a block away” in 1st gear, to a lesser extent in 2nd, etc (no racket revving, only in gear).

CV joints, bearings, anything belt driven, has been checked out.

Figured it was the transmission, but it shifts perfectly - and I’ve drained the oil twice, perfectly clear, and no shavings on the magnet.

I know the clutch is original (doesn’t slip, don’t want to spend $700 if I don’t have to).

The car, other then the noise, runs as if it’s new, and averages 34MPG, so I’d like to keep it!

Any ideas?

Thank you!


It sounds like a loose exhaust manifold heat shield or a catalytic converter heat shield. Either one can make a loud rattling sound at certain rpms.

I’d agree with @Jesmed1; on this. Heat shields are a common problem with rattling noises.
You might also want to check the dust shields behind the brakes.


Based on my experience with a 1999 Civic EX, I’d say jesmed1 and Yosemite are on the right track - although the “only in gear” factor is confounding. The heat shield around my catalytic converter has been loose and/or bent a few times; large hose clamps have sufficed to reattach and silence it. The exhaust manifold heat shield does rattle some - it is cracked around one of the two bolts that mount it to the top surface of the manfold. I hesitate to try to unsrew those bolts - they are likely to break in the removing.

For me the other source of buzz/rattle at certain RPMs has twice been the B pipe, ahead of the cat. It is a double-walled pipe. Last summer a local muffler shop diagnosed and replaced it within a hour, for less than $90. Gotta love your local muffler shop!

I found a pebble in my heat shield causing a funky rattle. Took some rapping on the exhaust with my fist to find it.

Heat shield fell off my '03 Civic a couple of years ago. Same kind of noise before it fell completely off. The exhaust pipe(s) seem to have a harmonic at certain rpm’s (1,800 is in that range) so you get the noise, then it goes away, then comes back etc.

Thanks for all the input guys! Hadn’t thought exhaust system, but again I can only produce the sound while the car is in gear.

I’m thinking it has to be in the transmission (which works perfectly), or somehow in the clutch assembly.

Thanks again.

“I’m thinking it has to be in the transmission (which works perfectly), or somehow in the clutch assembly.”

Can you get the sound to change by pushing in clutch or popping tranny into neutral?

Yes, out of gear or clutch in and the sound goes away.

Any change (say, in first when it’s loudest) between accelerating, constant speed, or decelerating?

Yes, sound starts abruptly at about 1,800rpm, and changes with rpm.

It has to be the transmission… But one would think with that much racket (hear it from a block away) that something would show up in the oil or on the magnet.

I’ll bet it’s the release bearing on the clutch then.


Bad throw-out bearing? Guess it’ll cost $700 to find out!

Thanks guys.

I’m not getting transmission failure. Why would the same noise continue through all the gears at a diminishing volume? I assume in fourth gear, you wouldn’t be able to hear it a block away. Have you beat on the exhaust system at several places and in different directions with a gloved fist?

I only suggested diminished volume because it’s an 05’ Civic, a car with the distinction of ‘most road noise imaginable’.

The noise is obnoxious in 1st, noisy in 2nd, and barely detectable in 3rd. I just assumed the considerable road noise was masking it.

I will put the car on ramps and beat on the exhaust :slight_smile:

And why would exhaust only rattle while in gear?

The racket can not be produced out of gear, rolling or otherwise.

“And why would exhaust only rattle while in gear?”

In gear, there are unique torque reactions as the engine drives the wheel. This twisting of the engine directly affects the exhaust system movement. (Very tenuous logic, but it’s all I got.)

Could you put it on jack stand and reproduce the sounds with the tires off the ground?

I have a hard time believing a clutch throwout bearing makes a rattle that can be heard a block away. Maybe there’s something else that broke loose inside the transmission and is rattling around.

But i’m still leaning towards and exhaust rattle (heat shield, or pipes hitting something). Sometimes this won’t occur when the engine is out of gear, but only when the engine is under torque load in such a way that the exhaust system move slightly and bangs/vibrates against something else.

My heat shield rattles but you hardly hear it in neutral or park because the car isn’t moving or vibrating much. If its just a bit loose you may need more movement and shaking to get the noise