Rear Wheels Locked

[deputymarshall]

So...1992 LSL 135k.

For 5k miles has had a weird howl/moan from the driveline. It has seemed like the noise comes from the rear right corner or center of the car.

PO replaced both rear wheel bearings. Didn't address noise.

I bought new wheels/tires...that helped for some reason...but still a noise.

I replaced rear differential with low mileage used about 40 miles ago. Noise still there. I also did calipers and rotors and pads 40 miles ago.

5 miles ago the harmonic dampener/crank pulley went. I replaced that and accessory belts.

Last time I drove it, 1 1/2 miles from my house the brake light went on. 3/10's of a mile further on...I stopped for a redlight in traffic. When I put my foot on the accelerator the car would not move.

I tried reverse. Wouldn't move. I tried putting it in neutral and pushing it...wouldn't move.

I was blocking traffic, so I just gave it some gas to move it about 20 feet to the side of the road. Front wheels dug in and dragged the rear of the car...leaving skid marks from the rear wheels.

The rear wheels are locked up.

I released and jiggled the parking/emergency brake...didn't have any impact.

The rear wheels move several inches and rock back and forth (meaning the calipers are not locked up).

I tried putting in the FWD limp home fuse. No change.

Had it towed...

Seems like the emergency/parking brake has frozen in some catastrophic way...or the rear differential is toast...

Comments?

[SoCal LS-L]

Your rear differential is locked...... the rear wheels would not move even a couple degrees if the parking brake was stuck. Did you check the fluid to see if there are metal shavings? It really sounds like the rear diff was starved of gear oil ..... maybe bad seal Im not sure if the rear output from the transmission could lock up on its own from an internal problem, maybe someone else will shed some further light on the matter.

[deputymarshall]

Next morning, rear wheels turn fine.

Checked differential oil. Very low.

I think the differential heated up and seized and now that it's cooled down it's turning. Very interesting. Wheels wouldn't move an hour after the original problem.

I'll be amazed if I didn't damage the differential...but we'll see. It's possible it wasn't really hurt that much. I'm putting gear oil and LSD additive in and then I'll drive it...

In my defense, I've never torched an engine by running low on oil...

[deputymarshall]

Rear wheels still are "locked" when the car is on the ground. I lifted all 4 wheels and put it in reverse and 1st.

Front wheels turn. Rear wheels don't. Drive shaft does not turn either.

But I can spin the rear wheels by hand and they move in opposite directions...s they should with LSD.

So maybe input (or output...where it bolts to driveshaft) spline is damaged...or center differential is screwed up?

Weird...on my old differential the wheels cannot move independently of the input spline I think. And I think this is obviously as it should be.

Maybe the input spline is broken off in the differential? Buteven if that is so I don't understand why the car won't move.

When it's in the air, the front wheels are driven and I can move the the rear wheels freely by hand. When it's on the ground, it won't move. Seems like it should drive if only with power to the front wheels.

Maybe I'll disconnect the driveshaft to try and distinguish between a rear differential issue and a center differential problem.

[SoCal LS-L]

Given the state of your diff gear oil level, id have to say your diff is locked at the input shaft. You can disconnect the rear driveline to make sure, hopefully the transfer case is ok since they dont like a 100%/0% torque split for very long.

[deputymarshall]

Put the car down and tried to move it again...this time there was just a little hesitation and the car moved...both forward and reverse.

I think it must have taken a little soaking in gear oil to lube everything up.

I've test driven it and it seems fine, so I think I may be out of the woods.

I only drive 1 1/2 miles or so before I had the problem...so I doubt I had any impact on the transfer case.

Thanks for your help...