Hi G35 Drivers -

I have a 2006 G35 Coupe AT with 125,000 miles. It has recently started to "rattle" from the engine compartment (driver's side, I think) at 1500-1800 rpm under slow acceleration or slow cruising. The rattle gradually starts, gets louder, then IMMEDIATELY stops above ~1800 rpm. It's not a heat shield vibration - not as "metal" sounding as that - sounds more like some kind of small rotating rub...like a playing card rubbing against bike spokes. it's like a quick low "rat-tat-tat-tat-tat-tat-tat" until it gets up to speed, then all is well. It doesn't seem to be loosing any power, and it's not burning oil. It also doesn't seem to be a water pump bearing - much more constant and predictable than that. It does not rattle under quick acceleration, and rattles at low rpm (below 2000) - I can't seem to produce the same sound when it's idling and I bring up the rpms in neutral, but it also sounds like it's too "high" in position to be a tranny noise. No engine codes either. Everything I've read here says "heat shield" but I swear that's not it - I know that sound, and this is definitely something more "mechanical" than two thin pieces of metal vibrating at a broken weld. Anyone heard this before? Maybe a belt tensioner going bad?

Thanks;
Don

 

We could post 20 pages on what might be causing the noise, in reality all you need to do is get your car on a rack/pop the hood and try to duplicate the noise. What is the noise in time with, motor rotation/wheel rotation? What kinda shape is your drive belt in? There are endless possibilities keep looking you'll find the noise...Gary

 

Just to follow up on this post - I decided to change the oil before taking it in to the mechanic to have a look at the mysterious noise. It was due - upon draining the oil, I got *maybe* a half quart of oil from the engine...WHAT??? There was no oil indicator on the dash, no indication at all of it being low on oil. Five quarts of Penzoil Platinum synthetic and a new filter, and my engine is purring like a kitten...no "rattle." Lesson learned. Check/change oil more frequently. I feel like a tool. My poor G was suffering. This was the first oil change after buying it six months ago, but that's no excuse.