The viscous coupling on my 99 S70 AWD is failing, (at least it makes lots of noise in tight turns) and I really don’t want to remove the rear driveline, or pay the dealer to remove and replace. I have done quite a bit of research on the internet and have a theory question for the guru’s out there.

The viscous fluid is what makes the rotating plates inside the unit transfer torque because as the plates rotate at different speeds the fluid gets thicker. Since the fluid can not be easily replaced to make the unit function normally again, could the fluid be removed, flushed and replaced with a less viscous fluid like power steering fluid or automatic transmission fluid? That way the unit could stay in place, but the new fluid would never get thick enough to cause any friction and transfer torque while providing lubrication. This would render the AWD all but useless, but would allow the rear drive line to remain intact. Does this sound possible? Also is there a way to drain the viscous fluid out of the unit with out destroying it?

Thank you in advance

Oliver

Over a million Volvo miles and still smiling :-)