I have a 93 F150, 302, 4x4, 125K. I just changed the rear diff (no issues, just thought it would be a good idea to change it) and put in 75-90 Valvoline Synthetic, with friction modifiers (both were NAPA's recommendation). Took a test drive, all seemed good, also no leaks.

Today I noticed that when driving at highway speeds 50 mph+ when I let off accelerator there is a growling sound, not overly loud, the growl continues until almost completely stopped. When driving at less than 35-40 and decelerate no growl. I may be able to feel a slight vibration in the steering wheel, not sure. I cannot hear specifically where the sound is coming from. I put the tranny in neutral while I heard the sound and it did not change anything, growl was still there.

The ebrake is free, the front hubs are not hot. The 4x4 (auto hubs) engage and disengage just fine.

Any ideas? The rear end looked good when I had it open.

Chuck

 

have you checked your u- joints? it's just a hunch

 

No, thanks for the reply, just needing some ideas to start going through and isolating this noise. I was just leaning toward it being the diff since I just changed the oil.

I will check out the U-joints, also was wondeing about the drive shaft.

Any thoughts on this? Is it possible that some of the RTV sealant could have worked its way inside the pumkin and is causing trouble? Thes is a small bead of sealant that shows on the outside.

Chuck

 

I checked the fill hole today; I thik the problem may be that I had too much oil in. I let it drain down to the bottom of the hole, plugged it back up. Unfortunately by then I had to go to a wedding . . . I'll give it a trial run tomorrow and see if that was the problem

Chuck

 

Let me know how it turns out, I don't think the rtv sealant would cause the vibration, it shouldn't squeeze in that far and would set up if it did