Its not anything to do with the fact the vehicle is 4wd. The rear differential needs an additive added to the gear oil to keep the noise down. Go to any auto parts store and they will give you what you need. Also check the gear oil level it is probably low
A Geo Metro is a front wheel drive vehicle. When a squealing noise occurs when the wheel is turning, it can be an indication of damage to the CV joints.
Turning the steering wheel farthest left or right for a few seconds will cause a loud squealing.
The cause of the squealing sound is because you are turning the steering wheel completely to the right or left
check your wheel bearings
Probably a worn wheel bearing...have it looked at by a technician before it seizes.
Power Steering Fluid Or Power Steering Pump
if the pump has failed completely it will cause stiff turning, obviously not being assisted by power. if the pump is failing there may be a squealing sound when turned in either direction. This is not to be confused with the squealing made when turning the wheel to its limits.
Anytime I've ever heard a humming noise when turning the steering wheel on any vehicle,It has always been due to low power steering fluid
Many things can cause that, the simplest cause being lack of power steering fluid.
A bad bearing can cause can the front end of car to make a squeaking noise when turning steering wheel either direction. It can also be caused by bad suspension.
rear differential got lube? rear wheel bearings?
c/v axle is bad if its front wheel drive