Vehicle is a 1996 Blazer 4.3L 4 Wheel Drive, with close to 212,000 miles.
I don't ever use the 4WD.

So I have been noticing a "vuh vuh vuh vuh vuh" sound when driving, doesn't matter how fast I'm going, but the sound gets faster the faster I go.
It almost sounds like a wheel hub, but I checked them all and they're fine. I was thinking it may have been a tire with a bad belt, until...

Now I'm noticing that I'm leaking oil from the rear drive shaft, where it goes into the transfer case. There is a rubber sleeve that protrudes from the TC and when driving it is spewing oil everywhere.

I'm wondering if there is some kind of ball bearing inside this transfer case that went out, which was making the noise, and end up compromising the seal?

I'm by no means a mechanic, but I've recently replaced my ball joints and CV half shafts, successfully, which I'm proud of ;-) so I think I can do some kind of repairs. Hopefully this is not something I'll have to take to a mechanic.

Can someone please explain where this ball bearing is? I've tried Googling and looking at diagrams but there are like 4 different bearings inside that case, and I'm not sure which one is the one I need to replace. Output shaft bearing, pilot bearing, shift shaft bearing, etc there are different websites calling it different things.

Thanks in advance for all the replies. I hope to get some concrete advice so I can order the correct parts online and hopefully repair this correctly.

Regards,
BrandonG

 

the driveshaft that comes out of the transfercase is going to spin like 3-4 times faster then your tires are going. so if it sounds like the noise is as fast as the tires it wont be anything with the rear driveshaft.

theres no actual bearing that the driveshaft rides on it but there are some internally on the case. that leak back there is pretty common. i think all my trucks leak from there. you can check to make sure your fluid is full in the transfercase

 

Wow - I guess I should have thought about that, that the shaft will spin faster than the tires, due to smaller gears. Duh...

Thanks for that. I guess I will rotate tires and try to hear if the sound changes direction.
I can't tell where it's coming from.

 

feel the thread on your tires, like the inside and outside if they get kinda wavy they will make a kinda thumping/humming sound. if its a front wheel bearing it will usually change sound or get louder or quieter if you kinda steer back and forth while driving

 

Well I have tried listening when steering back and forth, no change in sound.

Also, I have went 60mph and then put it in neutral for 10 seconds, no change in sound.

Either it has to be a tire or a rear bearing, is what I am guessing, can someone confirm this?

About the leak coming out of the transfer case where the rear shaft comes out, is that something I'd be able to do on my own with basic tools?

Thanks again for the replies.

 

yeah them rear seals are pretty easy. just a screw driver and hammer and you can kinda just pop them out.