Transfer case slip

[Soliyou]

Hello everyone.

I have 2001 qx4 with all-mode transfer case and around 189k miles. I bought the qx4 around six months ago and I think the transfer case fluid was never changed.

The issue: when I select 4x4 via the switch, it is supposed to lock the into 4x4. In my other 4wd trucks, if you make a turn with 4wd locked on dirt roads, the wheels would hop. However, in this qx4, when turning, the transfer case clutches slip and I can feel the screeching in the drivetrain, no wheel hop at all! I changed the transfer case fluid 3 times, but it is still pretty dark.

The question: is it normal for this transfer case to allow slip when turning? Or clutches are gone? I am worried it would also slip in a straight line in a high demand situation.

[mdmellott]

Not that familiar with these all-mode 4WD models but I would run through all the component diagnostic and symptom checks outlined in the service manual first, before considering an overhaul of the transfer case. https://www.nicoclub.com/service-manual ... ansfer.pdf There is also a transfer oil filter element I would first remove, clean out with a suitable solvent to flush out any trapped particles that may be clogged up in the filter, and then reinstall it with new o-rings and seal. A clogged filter might be dropping line pressure needed to operate well. https://www.infinitipartsdeal.com/parts ... m=333_B006 Hope this works out for you without any major expense.

[Soliyou]

Thank you sir! So far, there are no drivability issues and no flashing lights (thankfully). So I doubt the self check will provide any input.

I looked at the diagrams and it seems that this T-Case is like a small transmission with planetary gears and a valve body! not the typical two gears+chain system. So I am thinking may be this is normal characteristic of this type of T-cases?!