My 2003 G35 Sedan (80,000 miles) has started making a strange noise at idle.
Its best described as being similar to a noisy heater fan or air conditioner idler pulley (constant hum), but all fan related items are off as is the air conditioner. While parked , the transmission can be shifted from N to Park to D with no change to the noise. Also accelerating the engine in park or Nuetral doesn't alter the sound. But when you place the car in drive and slowly accelerate, the noise seems to go away. It seems like some sort of transmission issue but I can't pinpoint the source of the noise.
Does this sound familiar to anyone?

thanks guys

 

Torque Converter? I'm just guessing?

 

I had the tranny checked over and no problems indicated. I also flushed the tranny and replace the synthetic fluid. No change in the noise level.
So thankfully its not the transmission.
I'll keep checking for the source. A stethoscope would be helpful.

 

i just got back from the shop. They were unable to detect the source of the noise. They suspected a pulsating fuel line, but were unable to totally eliminate the annoying sound (vibration or rattle) by hoisting the car and manually clamping the fuel lines. They said if its not a normal vibration, it could be a fuel tank pulser or eve a fuel pump that is ready to go out.

 

Ummm, what type of trans fluid did you use? If it wasnt Nissan J-matic, then you may not have a happy transmission for long. Nissan puts a bolt on the filler tube for a reason. If you did the change yourself without J-matic, I wouldnt tell the dealer what you did.

 

Also, when was the last transmission fluid change before the one you just did?

 

The local Nissan deal did the flush and refill. I made sure he used Nissan J. He indicated it was a synthetic and kindly charged me more for it.
Previous tranny work was at 35,000 miles.

 

The shop at Fresno Infinity fixed the problem rattle. They replaced the fuel pump. Initially, that didn't solve the problem because when I went to pick up the car the noise was still present. They took the car back into the shop and told me the new fuel pump was defective. After several days of trying to get the correct pump, they finally installed a new one and the rattle(rumble) was gone.