So a while back I posted about how the front diff in my GMC 2500HD was blowing gear oil out of the breather hose when I use 4WD (still is FYI, haven’t figured that one out)
Anyways, this was an abused ranch truck from Texas and the first winter I used 4WD, it started getting loud, like bearing whine loud. I wasn’t getting any worse mileage, it just got noisy.
Anyways I’ve had in the plans to have it rebuilt, but just have never got to it. It’s worked fine the last couple winters and I haven’t really had any issues with it.
However, this winter something changed, I had to use 4WD for the first time this winter a couple weeks ago and the diff got quiet! Like there’s a drone at low speed, but when I get up to 40+ mph, it’s quiet. It’s not making any more bearing whine. And yes, 4WD is working.
What is going on? Should I be expecting it to grenade soon? Did the car gods catch me a break?
Robbie
UltimaDork
2/17/19 9:46 p.m.
Oh man. I love it when my cars fix themselves!
But honestly, it's really hard to diagnose something that doesn't have any symptoms. So best you can do is drive it until you have some symptoms.
In reply to Robbie :
But it had symptoms! I’m not going crazy I swear!
Does it have manual hubs? Could be the hubs and not the diff, i had a similiar thing happen when my stock crappy manual hubs went out on my ranger
NickD
UberDork
2/18/19 7:44 a.m.
Antihero said:
Does it have manual hubs? Could be the hubs and not the diff, i had a similiar thing happen when my stock crappy manual hubs went out on my ranger
GM trucks don't use hubs for the 4WD in the way a Ford does
In my experience, parts tend to go quiet right before they explode.
NickD said:
In my experience, parts tend to go quiet right before they explode.
truth. and let me add: in my experience, things quit leaking when they are empty.
AngryCorvair said:
NickD said:
In my experience, parts tend to go quiet right before they explode.
truth. and let me add: in my experience, things quit leaking when they are empty.
And they run best/make the most power right before they pop...
Oh this is all helpful thanks. 
