4WD issue

[05goatls2]

Hey guys, tried searching before asking, but my 4H doesn't work on my 93 Yukon. I THINK 4L works, I can hear a metallic sound clanking when I shift and it feels like its working, but when I shift to 4H nothing happens. What could it be? Thanks

 

[SunlitComet]

4hi can be quiet like. do you get and engagement light in either mode?

 

[05goatls2]

No, I don't get a light in either mode. Would this light be on the dash? My shifter is an old school floor shifter. In 4L when I actually drive, I hear a whirring while I drive coming from the front. Is that normal?

 

[05goatls2]

UPDATE: Replaced the 4WD actuator and now it works! I actually have a light indicating I'm in 4WD on the floor shifter. I can definitely feel it in 4HI/4LO. Who knows how long this 4WD hasn't worked.

Here's my next set of questions. What're some things I should do to make sure my front differential components are ready for offroading? What I'm getting at, is should I grease or lubricate anything, maybe replace the fluid? I'm a FWD newb at best. I just don't want to get too excited, go to the beach to test it all out and mess something up because I jumped the gun.

 

[SunlitComet]

sorry i forgot your post. grease anything with zerk fitting but do not blow out any ones that got rubber seals that are already puffed out and stiff.change out you axle fluids before you go if you don't know its condition. if you get deep in water then inspect the fluids afterwards.

 

[Donnie Yukonie]

what sun said
also check for leaks , u joint life , tow hooks ect..
ALSO DONT GO ALONE and make sure you bring at least two types of recovery equpment I.E tow straps
and if your new take it easy on you and your truck first time offroaders are keen for accidents and breaks , use common sense and a little brains and you will have fun
stay safe

 

[05goatls2]

Changed the differential fluid, at first I thought i accidentally loosed the oil pan because of how dark the oil was!!

Seems to be a bit smoother, however I still hear that loud whine in 4LO while I'm accelerating. Any ideas? Is it the ring gear?