differential noise

My wife's 2006 manual Jetta (96,000 miles) has a hum/howl between 60 and 70 mph. She says it has made the noise for a year, but didn't think it was important, so didn't say anything about it. It's been at least 10,000 miles, I figure.

It lessens when you let off the throttle or go down hills and returns when you get back on it or go up hill. There is no change when turning left or right. It shifts smoothly. The noise is the same whether in 4th or 5th gear. No leaks or torn transaxle boots.So I'm pretty sure it is a differential problem.

I need advice on a fluid change that could allow me to slow up the damage until I can afford to replace the differential unit. I just finished having the timing belt changed and the camshaft replaced (thanks, Whitedog!), so I am really not in a position to drop another grand into the car for at least 6 months.

Would using a gear oil with a different viscosity help me baby it for a while? Any other inexpensive short term solutions?

Thanks in advance,

Kirk

Kirk,

If this is the original fluid simply changing it may help. The stuff does shear down to a lower viscosity over time and turns acidic as well. The OEM VW fluid, the Amsoil 75w-90(MTG/GL-4) and the Redline MT-90 all work well.

TS

Grab an axle flange and see how wiggly it is.

Changing fluid didn't help the noise. There was a small amount of iron on the magnet, but not very much. Worth a try, though.

Ok, I'll pull the wheels and wiggle the axles tomorrow, but how much wiggle is too much?

thanks,

Kirk

You don't need to pull the wheels. Just grab the output flange/joint and pull up & down. Should be completely solid.

Ok, will do.

Did the differential turn out to be the problem? I am having the exact issue, and I think it's what is making the noise. As it only makes the noise under load at 60-70mph, it is hard to troubleshoot!