I have inspected all four real wheel bearings. On one of them, both the rollers and outer race have a "seemingly perfect" mirror-like finish.
The other three have a "flat-like-paint" or "satin" appearance to them, both in the rolling area of the outer races, and also on the roller bearing surfaces. They are not pitted or discolored. In fact, I went through the entire Timken guide to failing bearings, and nothing matched my bearings. Well, except the original exemplar of what a good bearing should look like, which I note was flat and not chrome-shiny.
All of them roll exactly as you'd expect, with no bench indication of a problem. I have since repacked them and run them 100 miles with no indication of trouble.
Is it possible my 3 bearings are good and the shiny one has a defect?
Reasons I think there might be a problem:
- 250,000 miles on these bearings, but it's a very light car
- Car ran for tens of thousands of miles too loose, and had a tiny amount of play. This was due to using the old GM preload method* rather than the shop manual method **. The difference is considerable.
- At one point on rural western freeways (80 mph) the right rear (both bearings satin) started growling. Slowing to 45 made it stop. This happened for a few miles then went away on its own and did not return in 1500 more miles of 80 mph driving.
- Physical inspection of the right bearing seat showed slight discoloration, like a bearing spinning on the seat (i.e. Stalled bearing). No galling or anything a finger could feel, and no burned or stinky grease there. I didn't even mic it, it was so minor.
- Old grease in the right inner bearing was brown/gray and smelled a little burnt.
Can this be continued in service? It'll have plenty more high speed, long cruise rural driving.
Sorry, I don't have any means to post a photo of sufficient clarity (I don't have a macro-lens camera, and my phone is way too stupid to focus on the right thing inside a part like that). Also, it's been repacked and buttoned up again, and I don't plan to reopen it without a good reason.
* seat with a couple foot-pounds, back off, then finger tight, then tighten to the next castle slot (e.g. 10-60 degrees)
** seat by torquing to 20 ft.lb., back off, then tighten until when bearing drag adds 8-18 inch-pounds of resistance to wheel rotation. Castle provided every 10 degrees.