It seems like 4WD issues seem to come up when people need it the most, ie winter driving. The buttons get pressed and the system fails to engage correctly.

I have owned 4WD vehicles for over 25 years and to date have never had a problem. I am either lucky or what I do helps keep it working.

Here is all I do. At least once a month, when it is raining, I put it into 4WD for maybe a mile. I do this just to activate the system and make sure it works. I do try to use 4LO but only if I can find some mud or a gravel road to drive on for a bit.

When I first got my blazer it seemed sluggish engaging the 4WD and it was positively nasty going into and out of 4lo. I knew this wasn't right. After maybe 3 or 4 months of putting it into 4WD when I could I started to really notice a difference and now, two years later and 150K miles, all works like it should.

Does anybody have any maintenance tips that they do?

 

kinda reminds me of work, soon as the first cold day comes, everyone brings their car in complaining they have no heat. but yeah i think even the owners manual tells you to engage it occasionally. on the older trucks it with locking hubs they recommend you drive it with the hubs locked for a mile or so to lubricate everything in the front axle and transfercase.

im scared to mess with most 4wd's we get people bringing them in for winter check ups and id say about 1 out of every 5 older IFS trucks. something goes wrong, the 4wd doesnt disengage, or makes all sorts of noise, or throws a abs or 4wd light. so maybe its the same concept people dont want to mess with it til they need it by then its too late

 

NP1, NV233 2 speed selectable transfer case, (3 button switch): Change the fluid once a year, DexronVI fluid. Operate in 4HI and 4LO once a month. Do not operate on dry roads in 4HI or 4LO.

NP8, NV236 2 speed automatic transfer case, (4 button switch): Change the fluid once a year, GM Auto Track fluid ONLY. Operate in Auto, 4HI and 4LO once a month. Do not operate on dry roads in 4HI or 4LO.

With both transfer cases: make sure all four tires are inflated equally, and that they are the same size, and same brand, (circumference must be the same on all 4 tires). If a problem occurs you'll notice it, don't wait, fix it!

 

but what about the 2 button switches on first gens? :P

 

Better check the owners manual, not sure on the fluid, but probably DexronVI. Do not operate on dry roads in 4WD.

The NV136 Smartrac AWD, and the NV236 when in the "Auto" position, are the only cases with a clutch pack, and they can be driven on dry pavement in AWD/4WD.

 

I think you are right on the dex6 for the fluid. and as for operating 4wd on dry roads... never do that LOL! That is why I flipped out so much when it would not disengage.

what about fluid changes, how many miles. I might do it this spring/summer since I dont know the last time it was done anyways.

what does the front diff tank, and what about the rear diff?

I am 98% sure I have a g80 in there now from the previous owner, he said he put in a different rear end and rebuilt it ( there is a receipt somewhere in my pile stating it was rebuilt in 2010) But all I know is... both tires have power all the time in the rear (makes donuts extremely fun)

 

How many miles? Owners manual probably says 50K. Dexron VI is cheap, only takes a couple of quarts.... go ahead and splurge

Both differentials use 80W90 with no additives, (friction modifiers). G80? Both sides powered? Not equally, not unless something's wrong. G80 is limited slip. One wheel is powered, if it starts to slip, power is split between the two sides, and it can alternate side to side, (torque varies). GU6 is open, (always slips). Maybe they put in a posi-traction differential On posi traction differentials, both wheels are powered equally, that's why they tend to chatter around corners, but go like hell straight ahead. Gotta use friction modifiers in them to cut down on the chatter.

 

What transfercase is the one with the shifter on the floor? Fluid requirments? service interval?

Thanks. Good information. I got a supervisor with a 00 Bravada in the 2 years I have worked with him I asked him when he changes his due to me just buying a blazer... he said in the 7 years he has had it he never changed it.. its the awd or smart track.

 

Shifter on the floor is an NV231 and uses DexronVI. The Bravada has a NV136 single speed transfer case. It has a clutch pack and an oil pump inside. He's asking for trouble if it hasn't been changed. It takes a special fluid available only at a GM dealer. Should be changed at least once a year.

 

Richphotos, if both tires have power all the time it may have a spool or was welded to lock them together