So last spring I replaced the bearings in my viscous coupler because there was an audible whine that I wanted to take care of. The replacement went smooth, and it solved the problem. After removing the bearings, it was clear that one of the bearings was not smooth and was the cause of the whine. That was ~7 months and a few thousand miles ago, and everything was great. However, just recently I was driving down the road and suddenly I started detecting the same whine. Its too damn cold this time of year to mess with it myself so I took it to the mechanic. They said it was the a noise from the rear diff and that it would need to be replaced, though the oil looks good so no damage to the gears. So I'm looking at doing the fix myself again. Why replace the whole rear diff if its just the bearings, right?
Can anybody shed some light on this? I'll replace the bearings again myself when it warms up a bit. The oem bearings are cheap enough on toyotapartsdeal.com, and its a fairly easy job and doesn't take long. Am I overlooking something here? I'm perplexed why the bearings would fail again. Could they have been faulty and its just a coincidence? Perhaps my repair job was not up to par? Or is it possible that there is another issue (with the rear diff, or an out of alignment drive shaft) that is causing the bearings to be damaged. Though, there are no other apparent issues.
2005 Vibe AWD, 175k miles