Here we go again...

Hello all, I recently developed a popping and squeaking noise, as well as some strange vibrations from the back on my 1987 Corvette Base Coupe with 101,000 miles on it. It is an automatic with the 2.59 gears in the differential. I started by replacing a wheel bearing as I had some play in the rear drivers side wheel after doing some inspection on the noise. The squeaking went away, but the popping remains. I counted two pops per revolution of the tire, so I went in to replace the u joints with hopes of eliminating the noise. Upon inspection from under the car, I found an oil leak located at the front of my differential leaking onto my exhaust right after it splits. I had smelt a burning smell for a while now, but I assumed it was my brakes as I only smelt it under heavy braking. I stopped there and went online to figure out what's going on. I hope it is the u joints so I only have to deal with a differential leak for a little while, or at least just low differential fluid, until I can put a 3.07 in the back. I have not heard any whirring noises or any issues from turning. It tends to come and go, mostly coming back on acceleration and going away after driving. Has anyone else experienced similar symptoms from their Vette, and does anyone have suggestions of how I can diagnose the issue?

Below is a picture I took of the passenger side of the differential. This seems to be where the worst of it is coming from, the drivers side does not look near as bad.




Thanks,
-Will

 

Without hearing the double pop, I would agree with the U joints. I would replace them all, and not drive it until they were done, Rear pinion leaks are funny, I've seen some just drip for ever, and then some sling fluid all over the place, where you had to add 1 quart every day. You might add 75-140 which might buy some time, but all bets are off as far as how long.If you decide to replace it, just mark the nut so it goes back in the exact same position so you are pretty close with bearing preload.

 

Update:
I just went for a very twisty, spirited drive and I didn’t hear anything. Typical occurrence for me when I find an issue. I try to diagnose a little better and it doesn’t occur. I maybe heard some squeaking, but the locusts and cicadas are so bad here in Indiana that I couldn’t differentiate their noise to car issue noises.

I sadly can’t keep off the car as it’s my daily driver, so I will likely drive it until I hear the noise again to get a better sense of what causes it and get some better information if more is needed.