The front wheels are engaged with a thermal engagement system. (forgive, I can't think of the exact name) The way the device works is a small charge of gas sits inside a cyclinder, and in front of a heating element. when the gas is heated it builds pressure in the cylinder, and pushes a small plunger forward, and engages the clutch. It's possible that the plunger is failing to completely disengage. They don't usually fail like that. Usually they lose the gas charge, or the heating element dies, and fail to engage. If the front dif is only partially engaged, or nearly engaged it will sound like someone who's just learning to shift in a standard trans. Lots of hard gear grinding. As an easy test you can unscrew the thermal actuator about half way, and then try driving it around. Or you can take it out completely, as long as you have something to plug the hole with, like the temporary rubber freeze plugs. Otherwise you'll lose diff heavy gear oil.
If you find that the actuator is faulty you'll have to replace it, and this may be a better alternative.
http://www.4x4posi-lok.com/app_chevy-k.html
I recently made a perm-lok (bottom of webpage) out of my old thermal actuator, metal tent spike, a large rubber eraser, and 3 set screws. If I ever find the time, I'll post a tutorial. Of course, if enough people ask about it, I may post it sooner....
Hope this helps you.
If you find that the actuator is faulty you'll have to replace it, and this may be a better alternative.
http://www.4x4posi-lok.com/app_chevy-k.html
I recently made a perm-lok (bottom of webpage) out of my old thermal actuator, metal tent spike, a large rubber eraser, and 3 set screws. If I ever find the time, I'll post a tutorial. Of course, if enough people ask about it, I may post it sooner....
Hope this helps you.
