I have a 99 CL and have noticed that it makes a rattling noise (sounds like metal on metal making a tapping noise) when the engine is cool. At first I thought the muffler was loose, but then realized that it only happens when it first starts. This happens while idling and going into first gear. Not sure if it does it at higher gears/speeds as well, but I don't hear anything. Car is otherwise in great condition. Has 150K mis. on it, fyi. It mainly does it when u rev the engine at the lower speed and/or at idle. Anyone know what I should check out to find the source of the problem?

 

Since you can make it happen without driving, first thing is pinpoint the location. Have someone rev it (or whatever) while you open the hood & listen.

 

Thanks Jim, I'll try that tonight and post the outcome.

 

I should add a couple things to check...

Tranny in NEUTRAL.
Clutch DISENGAGED (pedal pressed down).
Can you make the noise this way?

Tranny in neutral.
Clutch ENGAGED (pedal UP).
Can you make the noise this way?

 

Thanks for your suggestions, Jim! Ok, here's exactly what happens: Sitting in neutral, if you rev the engine any amount, there is a rattle noise. It only happens as the rpms increase, though. If you hold your foot steady on the accelerator, it stops (i.e. if you hold steady at xxxxrpm). Sounds as though it's coming from the underside toward the front - I think this is the area of the catalytic converter...? Can't see anything vibrating or moving when you look under the car (not on a jack). Oh, clutch engaged or disengaged makes no difference. Any ideas??

 

Alot of hondas are notorius for having the heat shield on the catalytic converter rattling loose. I had a 97 gsr that did that and did the same thing you're describing. I'd let it cool down, jack it up, and check all the bolts on the heat shield to make sure they are tight. I've also had the bearings break on an aftermarket short shifter and it gave me the same problem with the rattling noise but you could feel the sloppy shifter and there was no doubt where it was coming from.

 

Awesome. That makes sense as it sounds like something is loose and it's shifts w/o a problem, so I know it's not the shifter. I'll check out the heat shield this weekend & let you know what comes of it. Thanks!

 

I agree with the heat shield. You might get some big fender washers to put it back on, or even a huge hose clamp.

 

Thanks Jim!