GMC transfer case

[Cedar Ed]

Any one like the old full time 4x4?It's a 203,I think?Getting my wood hauler ready to go. Checked the oil in the filler hole,it supposed to be a half inch down when full , and put in two quarts already,and still not full!
And it isn't leaking at all. Should I keeping adding oil,and just hope it has no damage,or maybe it will be ok since it wasn't used in low loc,just high range?

 

[Fred482]

Not sure where the oil is going or why you have to add so much to bring it up to the proper level. One thought, there are two sections to the case, both sharing the same lubricant. It often takes some time for the oil to seep into all areas of the cases. I've filled t-cases after overhaul, let them sit or even test drive them, recheck and add more fluid. Pretty normal process to drive them and have to add more fluid.

I just finished replacing a range shift fork and fork inserts in my NP208. A fairly common problem. I did have to fill the case, drive it, wait a while and refill it to achieve the proper fluid level. The NP208 does have and oil pump that lubes the upper section, so it takes some drive time to get the upper section full of fluid after disassembly.

The NP203 does supposedly require 10W-30 or 10W-40 to properly lubricate the small bearing surfaces. This information is from my GMC Unit Overhaul Manual, dated April 1973. I remember a lot of dealership discussion about different lubes, ATF, 10W-30, 15-40W, GL-5, 90-140wt. gear lube, etc. It seemed to go on forever as to which was correct. The GM factory zone service rep told us to use ATF to be on the "safe side" as he put it....;-) He didn't know for sure either. The only lube related failure that I remember from those days was one truck that the owner had drained and refilled with SAE 90-140 gear lube. It did cook the needle bearings. He used 4 lock quite a bit, probably contributed to this failure. Just info, no judgements....:msp_rolleyes:

 

[Cedar Ed]

I decided to fill it with 10w-40.I added about 3 quarts by the time it came up to the full level,which tells me it still had about a quart of some "unknown"fluid left in the case.A good thing because,breaking parts is a PITA.And then after checking the rear differential,it too was very low,I put in a quart an a half of some SAE80w-90 GL-5 in the 14 bolt rearend. It's a good thing to check the "other"fluids,I kind of take them for granted,for awile,only checking the ones under the hood,and trusting the jiffy lube,no more.Getting back to regular maintenance from now on,feels like I avoided catasthopic failure,in the nick of time.:msp_thumbup:

Now, I am going out to try and grease those hard to reach spots on the driveshafts.In the c.v. joints I think they're called?

 

[Fred482]

The CV joint, depending on the type (there are several different designs) can be troublesome. I found it easier, on my truck, to disconnect the front u-joint from the differential flange. This allowed me to swing the drive shaft sideways far enough to gain easier access to the center of the CV. There is a recessed fitting that allows for a needle grease gun tip to properly lube the center bearing of the CV joint. Again, depending on the type of joint, this may or may not be seen on your drive shaft. Some had a pivot ball to center the CV, others had a needle roller bearing. Both types need to be lubed.

One very early style didn't allow for any type of grease fitting, it wasn't drilled anywhere. The only way to grease the pin & bearing was to remove one u-joint to gain access. That one was short lived, thank heavens, what a pain. By the time you drove the u-joint caps out, lost half the needles, etc., it was time to take a break......:msp_biggrin: