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!
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!
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.
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’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?
“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.)
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
