My 2009 RX-8 has been having idling issues. Whenever I'm in gear (D, it's an auto) the car vibrates. The side-view mirror on the driver side visibly vibrates with the car, which makes me think it's vibrating a bit more than it should be. This I don't think I would mind much, but occasionally it gets much worse and something seems to be rattling from the front end of the car.

I've attached a video I made of the last time it was rattling. It's a little difficult to hear, but in person it's much louder and more alarming than it seems to be in the video. You'll notice that at about 12 seconds when I start to pull away from the light the sound immediately stops. Shifting into neutral or park also stops the rattle, and actually cuts down on the vibrating that always happens at idle too.

Other than this, the car runs beautifully. Plugs and coils have recently been replaced about 1000 miles ago, but the initial vibrating issue (or at least the vibrating side mirror...) was there from before. I think the rattle came after, but it happens so rarely that I can't be sure if I just missed it from having the radio on.

I've seen some complaints of vibration from bad motor mounts, but I think that was only a problem for the first few model years. Someone please correct me if I'm wrong.

Any ideas? Does this sound familiar to anyone? I'd rather not have to schedule a dealer visit since I don't know how much they'd charge and if they would even figure it out since it only rattles maybe once or twice a week for a few moments at a light. Thanks in advance for any help you can offer guys.

http://youtu.be/-G1Oiv4MySE

 

Motor mounts aren't something that magically don't ever fail just because it's an S2. There is NO part ever designed for any car that is immune to failure.


Motor mounts are rubber and wear out over time due to the elements, heat cycling, etc...

It's your problem.

 

Bummer. I was hoping it wasn't the motor mounts since the rattle happens rarely, but it would definitely explain the vibration at least. I was also really hoping it wasn't the motor mounts since I don't have the tools to fix that myself. Looks like I have a trip to the dealer scheduled to get this checked out.

Just to confirm though, do you think the bad rattle is also from the motor mounts? I'm not really a car expert and I can't think of why it only occasionally rattles instead of every time I'm at idle.

Thanks for the help.

 

It could be something that is getting shaken out of position, or shaken into position, with the reverse happening when you drive. Until you get your motor mounts checked out and/or replaced, it's not really going to be viable to diagnose a different periodic rattle.