Front Transfer Case output shaft bearing?

Had a weird vibration/distortion in the driveline that I couldn't find.

One of the things I do to try and diagnose a bearing problem is to actually crawl under the truck immediately after a long drive and literally feel each area or joint to see if they are excessively warm or hot, and it has never failed me.

Anyway, after driving 75mph on the highway for an hour or so, I pulled over and checked the U-joints, differentials, etc. When I placed my hand on the front output of the Transfer case, it was HOT!

I have an ADD 4WD automatic trans, so of course everything turns on the damn front driveline all the time (dumb). Any of you have experience with this potential (bearing) problem? Is it possible to change that front bearing without splitting the case? I doubt it, but thought I'd ask.

2001 Auto 3.4L 4WD. Transfer case fluid is fine.

 

So I may be mistaken, but I'm nearly positive that the front driveshaft doesn't spin in 2wd.

When 4wd is engaged, then sequentially 2 things happen, 1) the transfer case actuator engages and the front driveshaft will now spin, then 2) the ADD actuator engages the front diff (sending the power through the CV axles to the front wheels).

The CV axles therefore are always spinning, but not the front driveshaft.

I'd suggest driving your truck back on forth in the driveway with a friend (or your phone recording video) looking underneath and determining if the front driveshaft is spinning in 2wd (it shouldn't be). If it is, perhaps that could be part of your issue.

I've diagnosed 4wd not engaging in 2 -1st Gen Tacomas, and a 3rd Gen 4runner (all were ADD 4wd vehicles), and none of them had the front driveshaft spinning in 2wd.

 

Hmmm, another thing that I will have to check; thanks.

So now begs another question in light of your answer: why the heck would the front output of the transfer case be hot then?

 

Is it close to the exhaust or cat?

 

Oh no; it’s the yolk that drives the front driveshaft.

 

How hot is hot? Do you have access to an infrared thermometer?

I would expect some heat in the t-case.

 

Could be hot from spinning fast at 75mph when it really shouldn't be spinning. But I'm just speculating

 

Im having a similar problem, more of a whine issue. 95 tacoma shifts in and out of 4x4 fine but I think the front diff is locked causing the driveshaft to spin the transfer case while not engaged in 4x4.