Let me start by saying Happy Holidays to everyone. I hope you have had a happy and safe holiday season thus far. Now, to the matters at hand. I have a NP203 fulltime case in my 79. The other day I noticed a pretty nasty sound and vibration through the front end and t-case area. Today I pulled the front driveshaft out to investigate. I found that the cv joint(s) in the yoke that mates to the t-case has seperated at the center ( the knuckle ? ) and sheared the zerk off the u joint. I also checked the oil level in the case to find that it was 2.75 qts low. OUCH. I decided to leave the front shaft out until I could afford to replace the joints and road test the truck to see if the noise might have been coming from the inside the case somewhere due to operation w/ little or no lubrication. Much to my dismay, I put the truck in gear to find that it didn't want to budge without the front driveshaft connected. It tried to move w more engine rpm but never rolled. Anyone know what the heck this could be? Obviously there is something wrong inside the case, just not sure what.

Thanks in advance for any hints/tips/advice.

 

Actually, that is typical for the NP203 when the transfer case is not in HI-LOC or LO-LOC. If just in HI or LO, the center differential is open and all of the power will be put to the front output because it is not coupled to anything. When you put the transfer case in HI-LOC or LO-LOC, the center differential will lock up and allow you to drive.

 

Wow, I didn't know that. I have been driving the truck for a cpl months now in what I assumed to be hi loc. Guess I need to adjust the linkage? I have noticed that between low/low loc and hi/hi loc there is no noticable detent or " definite mechanical engagement" feel like there is going from low range to high range. Is that common as well? I had a 79 pick up and it had a light the illuminated when the 4wd was in loc mode, my blazer doesn't so it's hard to tell when it's actually loc'd. The linkage seems to be mounted securely and the shifter doesn't seem to have any real slop in it either. Thanks for your response cause I might have junked this case without ever knowing if it was truly bad or not!