4wd problems

Hi, I m new to the group and new to 4runners. I recently retired to Costa Rica, bought a 4wd 4runner and a house on a mountain side. It rains a lot and the driveway gets muddy so I need my 4wd in top shape. I recently got stuck in a friend's driveway and he had to pull me out with his Land Cruiser with the engine driven winch. He noticed that only one wheel was spinning, the right rear one.

I also hear a "boom" coming from the front right wheel area when in low 4 and stressing, such as coming down a big hill and using the low drive to keep me from racing down the hill.

How does 4wd work on my 90 4runner? I notice it seems to work whether the axle is locked out or not. Is it safe to shift into 4 when on the fly or is it necessary to stop, shift, and lock out.

 

Without looking at it, right off the bat I’d order 2 new axles and 2 front locking hubs for it. Start there and watch for anything obvious while your doing the work. It’s IFS so you don’t have to get out of the truck but you should come to a complete while engaging your 4 wheel drive.

Also check your front drive shaft for bad u joints. Well check em both while your under looking.

 

Did '90 use lockouts? The '93 I service is a vacuum CAD.

OP, I'd do some hands-on before spending any $.

First, visually inspect your CV's (rubber accordian boots) for any tears. If they're torn you'll get a horrible clicking in 4wd, especially when turning. Then look at u-joints on the front driveshaft. Give them a good shake and wiggle, there should be ZERO play.

Next, elevate front wheels and support the vehicle safely. In 2hi the front d/s should turn freely. In 4hi it should be locked in and will not turn by hand.

Now spin each front wheel. If you have a vacuum CAD the vehicle will need to be running. If you have lockouts, have them engaged. In 4hi it should cause the other front wheel to spin, possibly in the opposite direction. If it doesn't, something is not tying your CV's to your front differential - either CAD or a lockout.

The 4wd system has TWO distinct components and neither knows or cares what the either is doing:
1) the transfer case must POWER the front d/s - this is the lever on the floor
2) something must tie the front axles to the front differential.

Either one of the above can occur but until BOTH occur you don't get power to the front wheels.

You have open differentials so in the field in 4wd you should always get at least ONE front wheel and ONE rear wheel spinning, if stuck. If that occurs the system is working as intended. If you want more than that you need aftermarket parts like a differential locker or aggressive limited slip.

 

I was just kinda probing for info, the op isn’t really giving us much info. How long he’s had it, mileage, pictures etc. does he do his own wrenching ? That kinda thing.