Northwoods Snowman

OK, I'm not finding anything searching around so I'll pick your brains.

I've noticed a bit of a noise recently that I think is coming from my transfer case. My Jeep has 109K miles btw. I noticed it after the thing sat for about 3.5 weeks in the garage getting the rear main seal and head changed over the holidays. Didn't notice it before, but I had just bought in Nov. so I may not have been "in tune" with it yet to notice.

Anyway, I only hear the noise when the fan is on low or off and the radio is off; it's really quiet, but definitely noticeable when other noise making things are turned off. It's a kind of bearing/whirling sound. It does it in 2WD and 4WD, though I haven't actually tried it in 4LO, I will when I get a chance. Ever put pressure on the transfer case shifter while driving and not actually shift it, just put a little load either forward or backwards on it? It's that sound, but it gets louder when I put pressure on the shifter. I can wiggle the shifter around and find a sweet spot where it's the quietest, but it's still noticeable.

Doesn't seem to do it when I first take off in the morning or when the thing is cold, but after driving a little I can hear it. It's road speed related too. doesn't matter what gear the trans is in or the RPM of the engine. It gets louder/faster the faster I drive. It may just be because of the extra engine noise, but I notice it more when I'm holding speed or off the throttle.

Any ideas? When I get a chance I'm going to jack it up and run it with the wheels off the ground and poke around with my stethoscope but haven't done it yet. I tried to do it when I had the rear end up when I was working on the brakes, but I could only run it at idle speed since the wife wasn't handy to rev it up a little. Didn't hear anything odd at that time from underneath.

I'm stumped. Not really sure what I'm even looking for.

thundaluvin

Have you changed the tcase fluid since you bought it? Fluid could have lost its viscosity or you are low on tcase fluid. Mine made the same kinda sound, and the fluid was cooked. I would also check the ujoints and rear diff.

Modestmike

Are you sure it's coming from the tcase? I just went through my xj looking for the noise I thought was coming from my tcase. I changed the fluid in it and still had the noise. Turned out it was my rear ujoint transferring the noise and vibration up the the tcase. Changed it out and problem solved.

Northwoods Snowman

Yeah, forgot to mention I changed the fluid after first noticing it. Fluid looked more like engine oil than ATF, but sounded the same after. I've thought about U-joints, I'll have to check them.

I've been thinking it's the T-case because when I push or pull the shifter lever the noise gets a little louder. I've just ever been into one of the T-cases to really understand how it's working and what might cause that noise, if it is in fact in the T-case.

Oh, and when in the driver seat, it's coming from the center hump (I know there's a propper name for this) over the trans. I lean down by the center consol and I can hear it a lot better.

Northwoods Snowman

So I got the wheels up off the ground and did some probing with the stethoscope. Turns out the noise is in the T-case, and I suspect is either bearings on the front output shaft, or something to do with the chain. I can run it in 2WD and don't get the noise. I put in in 4WD and I do get the noise. Couldn't tell definitively where the noise was coming from in the case though, too much resonance. Any other possibilities of the source for the noise in the T-case I besides the bearings/chain?

I checked the U-joints and diffs and they are tight/quiet.

Keep in mind that the noise is present in 2WD when driving as the front axle and drive shaft are turning, but it wasn't present with the Jeep on jacks since the front wasn't in motion. Also, when listening around, I didn't hear any type of chain slap noise indicative of a really loose chain.

frsmith2

Curious, did you ever figure out what this is? I noticed this happening to mine this evening...low pitch "whirling" sound that changed in direct correlation to speed and seems to change when I put pressure on the 4wd shifter.

Northwoods Snowman

I think some of it was the front output bearing as the noise got quieter after rebuilding the T-case and that was the only bearing I could even find a hint of something wrong with. I still have the noise, but have attributed it to "normal" chain noise, though it's a good bit quieter than before the rebuild. Still louder than I think it should be, but at least I know it's in good shape now so I'm not going to worry unless the noise changes.

g33tar

I've got the same exact thing. Would love to know if you've fixed it, or just live with it at this point..