Viscous Couple Trouble

[TK McGuinness]

My 1998 V70XC AWD, with 201k miles has been making clankity, whirring noise for the last couple of thousand miles. At first it was just in corners, then it became more frequent. Now, it is constant EXCEPT under acceleration. (I had a truck with a bad U-joint that made a similar sound.) A mechanic looked at the front boots and said they were fine and suggested that the viscous couple is going bad. He also said that I can drive it until the noise really bothers me. (It does) That is a bugger and about $3k to replace. Can that be right??? Can this AWD unit be removed and driven safely without damaging the remaining drive system. In essence making this a front-wheel-drive only car? Later when I feel like dropping the 3k into it can it be made whole again? Would it be worth the price to do it now?

[JRL]

Just remove the propshaft ... 12 bolts
The Viscous Coupling usually does not go clankity clank if it goes bad (very rare), it's probably either a bad propshaft (common, $1K new or $400 refurbished) or a blown bevel gear ($$$) so just remove it for now and be in FWD (no issues doing this).
IF, it still makes noise, the bevel gear broke and that's another story

[BEJinFBK]

If you have a mechanic suggesting that you should keep driving
instead of dealing with the problem, my suggestion would be to
find anther mechanic.

Like Jim says, it's pretty easy to pull the drive shaft and go FWD
for now. That will also make it pretty easy to isolate your problem.

The DS has a CV at the front that is nearly dead certain to have a
baked boot, a U-joint in the center and a CV at the rear. There's also
a carrier bearing in the center supporting the DS in the middle.
These are the usual failure points to have a closer look at.

Once you know what needs attention, contact the friendly folks at
ColoradoDriveshaft.com. They'll fix you up with whatever you need
for waaaaay less than 3 K.

[TK McGuinness]

To clarify: I was on a road trip when the noise began and the mechanic who said it would be OK to drive was 1,000 miles from my home. He was assuring me that it would get me home...
Thanks for the advice. This is my first foray into AWD. I will go at it one thing at a time. HOPEFULLY it is not the bevel gear...

[JRL]

Let us know what it does after you remove the propshaft

[TK McGuinness]

Took out the prop shaft. Noise is GONE! I sourced it to the front end of the prop shaft. Pretty straight forward removal. 6-6mm bolts on the front and 6 at the rear and 2 -12mm bolts that secure the carrier berring. After 200k miles the bolts were a bit stiff but were eventually convinced to let loose...Thank you for all of your help on this. I guess now I will need a new (or refubished) prop shaft if I want to resume the AWD!

[JRL]

You can buy just the front bearing for $125 from www.coloradodriveshaft.com
or about $450 for a total rebuild

[BEJinFBK]

Front CV replacement is pretty easy.

Have your VIN handy along with a
measurement of the CV's diameter.

Then get your credit card out and
and contact Colorado Driveshaft.
They'll take good care of you.