Hi all,
First time poster, but been lurking unregistered on this forum for a while. Last month I picked up a used 2012 G37x Sedan with 67k miles on it. Dealer only gave me a powertrain warranty (which is fine with me), so I'm wondering if anyone knows what this might be before I pay my mechanic to take it in and look at it.

I have a ticking sound when I get over 2000rpm, but only when the car is moving. If I rev it while stationary it is completely silent. It seems to go away with speed, but cannot verify for sure since it is fairly hard to hear unless the windows are down and I'm driving next to something to reflect the sound back at me. While moving, if the car drops back below 2k, the sound appears to go away.It is a fairly hard tick, with a little bit of what I would describe as a squeak to it, but definitely pretty well in sync with the wheels (faster I go, faster it ticks until it seems to go away).

Any ideas? Thanks in advance.

 

Could be one of several things:
Brakes
Front CV joint
Driveshaft u-joint
Nail in a tire

 

Brakes or nail in a tire - I would think the noise would be present any time the wheel is turning, not just at high RPM's.

Driveshaft U Joint - could be, I can't say I've noticed vibrations in the car at highway speeds, but it's still new enough to me that I may not be in tune with it enough. I also don't notice anything when shifting.

Front CV Joint - There is no ticking when making a turn with the engine at idle.

I'm honestly wondering if something underneath is rubbing or knocking, but it's still puzzling to me that it only happens above 2k rpm. I'm going to jack it up tonight and see what I can see. Any other opinions are most welcome.

Thanks!

 

rock in a caliper or braKE dust shield?

 

Also look for exhaust leaks.

 

I don't think it is the brakes. It sounds much more mechanical. It consistently starts at 2k rpm and continues up through 3rd gear (tested in manual mode). However, it does increase in speed as the wheels spin faster. Anything I can do to check for sure?

As for an exhaust leak, I would think the sound would occur when revving in neutral - which is does not.

Jacked the car up and checked the driveshaft, everything seems tight. Nothing rubbing or bumping against the axles that I can find either. I'm stumped. I guess I'll have to buckle down and have my mechanic look at it. I was trying to avoid it since he's an hour away, but oh well. Thanks to all who contributed, if anyone else has any ideas I'm all ears.

 

I uploaded a video, in case anyone else has some bright ideas. I'd especially like to know if it sounds serious, since I can't get into my mechanic until next week.


Thanks again guys!

 

Could be catalytic heat shield

 

Did you ever find what it was?
I think I have the same problem, I'm going the check the driveshaft this weekend for play. It sounds like the g35x had wear in the front driveshaft on a few models.

 

So, I know this is late, but the dealer finally found the issue (after replacing all four wheel bearings and front drive shaft). Turned out it was the starter all along. Replaced that about a month ago, and all has been well.

Hopefully this helps someone from the future.