Image below shows the cross section of a typical oil seal. Yours may be different. The round thing in the center is the gaiter spring that holds the oil seal in firm contact to the shaft. This side should go toward the oil (inside of housing). The smaller lip on the left side is the dirt shield. It ...

Safely raise both rear wheels and put the transmission in neutral. Then turn each wheel while holding the other still. This should let you or a helper determine the source of the noise. Be aware that the differential will try to turn the other wheel in the opposite direction if it is not held still....

e777 wrote: ↑15 Jul 2021, 17:25...when the car is in motion and I shift to neutral, the grinding disappears. I shift back to drive and the grinding reappears.

This makes me think transmission, not rear end. The diff and driveshaft are still spinning while in motion.

This model should have a electric speed sensor at the rear differential. It has a magnetic pickup to a toothed wheel. If there is crud on the wheel, it might make noise. As BlackBart says, it might be transmission issue sounding like the rear. Getting the rear axle is raised, you should be better ab...

The two sides are out of alignment. Look at them again and align them. Use diagonal measurements to check for square when adjusting the two sides.
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It’s not rocket science but you do need a good machinists square..basically a piece of milled steel that is proof straight. I’ve long since valued a machine shop cost over my solvent, cleaning cost, and foobarring the warp measureent though. My local shop charges $25 to dip , clean , and measure a h...

I replaced the head on my 1992 940 GL(non turbo) with a head I found at Pick n Pull. I was fortunate though. Afte I cleaned it up (replacement head) and cleaned the carbon off the pistons I installed the head as is, even using the same head bolts. The red block engines are a marvel of engineering. I...

Loosen head bolts in reverse order pattern (starting at the ends).

Have you seen any evidence of the dreaded biodegrading wire harness on this Volvo? I think Volvo changed the wiring insulation by 199, but it still may occur. If you are not familiar with this problem, The wire insulation crumbles away until wires in a common harness short to other wires. Weird ligh...

Look at hot areas like near headlights and over the engine. Also where exposed to the sun.
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