I'll do my best to describe this.

What I've narrowed down is that the sound only happens under very light throttle. Once I've gotten up to 45mph and just maintaining speed, what I can only describe it as vibrating rattle sound comes and goes. I can make it stops once I either give it more throttle (from about 10% to about 25%) or completely lift my foot, 0% throttle. I haven't noticed this under highway speeds. Only under light load and approximately 2k RPM's.

It doesn't do it all the time, and it comes and goes on it's own, without me changing the throttle, when I allow it. I have thought it may be a loose pulley, and I haven't had a chance to really check that.

It also makes the sound when the AC is running and when it is not. I do not notice any change in speed, nor throttle response. If there wasn't the sound, I'd say that there isn't anything wrong.

Any thoughts?

 

Valve noise perhaps? or...PCV valve noise? More throttle = less vacuum and more compression. No throttle = maximum vacuum.

or...

Some other simple "resonance" - check around for any loose or rattling parts.

Bob

 

thanks for the input. I don't think it's a valve noise, due to the face that it comes and goes, without anything changing. The longest I've been able to keep it going is about 5-7 seconds.
A PCV valve noise, I'll try and look into that. Thanks again.

 

Unfortunately just one of many things that can rattle how you describe - good luck tracking it down.

Bob

 

Check the int. axle shaft heat shield. I think Honda has a TSB out on this for a noise/vibration.

 

I second heat sheild exhuast or otherwise.

 

Throttle cable bracket on firewall. I've seen them rattle. Bend it out and see if the noise goes away.

 

way late reply, but I will take a look at the heat shield and throttle cable bracket. Thanks a ton guys

 

there is a service bulletin about the half-shaft. simply loosen the 3 bolts and shift the shield either to the left or the right. the direction doesn't matter. then tighten the bolts to 21 ft/lbs. careful not to over tighten them or they will strip. ask me how I know. that should get rid of your noise. the bulletin applies to 03-05 Pilots, 05 Odysseys and 03-05 V6 Accords.

 

I doubled checked the bulletin. It DOES NOT apply to 04 pilot! Ive seen the resonator (in the exhaust system) come apart and cause a rattle. Tap on the exhaust system with a rubber mallet in strategic areas to confirm.

 

Does the A/C coming on change the pitch or intensity of the noise at all? If you sit there with the car in DRIVE and press the brake to hold the vehicle and press the accelerator pedal a bit, can you duplicate the noise as well?

Also you can check this since it's easy, free and takes a few seconds...where the top of the washer fluid bottle mounts to the side of the engine bay, look and see if the clip there (if applicable) is in place and secure. Ridgelines had an issue with the clips coming out or were missing and caused a rattle noise. I know it sounds odd but I've diagnosed and repaired some pretty odd things at work and I no longer overlook obvious, strange or otherwise OK-looking parts or connections.

Rattle noises are a bit hard to diagnose online due to the variety of things they can be caused by. If you havnen't noticed a change in driveability, I'd take it into a dealer whenever you have some time to have it looked at if the noise concerns you.

 

Did you ever find a solution to the weird sound on your Pilot? I also have a 2004 and your description is pretty much what I have on mine. It's a kind of buzzing / rattling noise that is intermittent, does not affect perfomance in any way, and goes away if I nail the throttle or take my foot off it. Thanks.

 

common problem for all pilots and mdx's...its the transmission