Hi Guys,
2001 XE, 75,000 miles, auto. Running good, but noticed a very slight transmission "wow..wow" rythmical noise between 25 and 40 mph in 2 wheel or 4. Could be normal with all that stuff for 4X4 under there, and recently have not had Led Zep at volume 500 ...so, do all Xterra's do this. Wheel bearings and trany fluid done several months ago and there are no leaks.

Its kind of hard to imagine what your "wow..wow" might sound like , but I would start looking at the rears and drive shafts fisrt, unless you are certain it is from the tranny already.

I think I know the sound you are talking about. If its what I'm thinking, you are probably getting ready to crap out your rear diff. An easy way to check this to to drain the fluid, but filter it with a shop rag as its going into your drain. When the fluid is all passed your filter look for metal bits. Check the magnet on the drain plug as well.

I've gone through two rear ends on two different Crown Victorias that made a very annoying "wow...wow" that got louder and more intense as it progressed. Apparently, there is an issue with the Ford axles they put in the CV's. I remember there was an issue with the rear ends on the early Xterras, but that should have made itself known by now if it was that problem.

Thanks guys, turns out it was the tires. The fronts were slightly cupped, so rotation did the trick. They are Yokohamas with a fairly agressive tread.