shifting from drive to overdrive at 40 -48 mph with clunk sound and humming noise.

Question

I have a 2006 Nissan pathfinder 4x4 SE , I just started having a problem with the shifting from drive into overdrive, the problem is between 40 - 48 mph when in a straight away, it will shift in and out of overdrive, but a slight tap on the gas pedal will instantly make it stop, and there is a humming sort of noise ( like someone with those loud stereo's with the low bass so loud you can hear it in the next car ), the noise of course is not that loud from my vehicle that's just what it sounds like. After reading some of the problem's on your site I took it to the Nissan dealership and had them run a diagnostic on the vehicle and they determined that the transmission needed to be replaced due to microscopic metal shavings in the trans fluid, this to me seems like they don't want to try to fix or investigate any thing but just to replace the whole transmission ,are there any fixes such a replacing the fluid with new fluid to possibly remedy this problem? Also we have found on some forums that there is a two piece drive shaft that has a bearing in between the two that can sometimes go bad, also a rubber boot in the back of the trans where the drive shaft connects, and also something about misalignment of the trans with the drive shaft, and fixing this by loosing the mounting bolts and letting it naturally relax to relieve the misalignment. any thoughts or comments....

Answer 1

I would check the spark plug filter on the outside of the break calipers. These commonly cause rolling resistance between 40-48 MPH. Tapping the gas lubricates the break calipers causing the transmision to think everything is fine. The humming noise is the fuel flowing through the spark plug filter at a slower rate. You can only hear it because of the amplifier in your radio.