Front end locked in 4X4 ?

[Mr D 73]

Hello all I'm new to your site here but was told there are some real die hard Van heads here so I'm going to pick your brains. I have a 1996 Safari AWD SLT and recently went over 300,0000 miles and have never had any major issues other than basic maintenance and general upkeep until a few days ago. Heres my problem when I'm trying to turn into a parking spot or make a tight turn the van acts like its in 4 low like an old style 4x4 pick up in low. If you stop and back up a few feet it will make a popping noise and then you can go back to drive and it will sometimes work. I have a feeling this is the front diff going out would this be a correct assessment. Any help would be appreciated greatly.

[Captn. Crunch]

I don't think it's your front diff. Your 96 should have the pre-electronic transfer case. If true you have a viscous coupling type case. These coupling have a fluid that becomes semi solid when subjected to shear as when wheel speed differences are present. These couplings fail when the fluid can no longer resort back to a liquid state and will be putting power to your front diff at all times. Jack all four wheels off the ground trans in neutral. Spin a front wheel. If rears spin also you need to change your viscous coupling