Spinning backwheels in 4-WD

If one hub is locked and the other is open, the differential will send the power to the open axle (path of least resistance) and not try to drive the wheel which is locked, therefore neither wheel turns as the diff just turns an open axle. To get roundthis you need a diff locker.

It’s the same problem if you have one wheel in the air, it spins with no drive to the other wheel.

Most likely you have a sticking hub or possibly a blocked vac line on one side.

I have had this before and when I checked both locked fine. Eventually both vac lines became blocked and I swapped to manual hubs, you now for sure when they are locked and they don’t fail.

Robin

wrote:

Thanks for the explanation. I don get this fully:

"If one hub goes click= 4wd engages and clack=4wd disengages, but not the other then there is probably a blockage in the pipes."

What will be the effekt on the car if only one hub "click"? I suspect that is what happens accoring to how it sounds.
 

The front axle will not drive- which seems to be your problem.