aris_unlimited

About 10 months back I got stuck in about 1/2 an inch of water that was sitting on top of some packed down snow. Front tires wouldn't spin at all. I did put it in 4wd after being stuck and I was told that I needed to go into 4wd and drive the suv for a bit before it actually kicked in, so I figured that was the problem.

Fast forward to a couple days ago. Went down some gravel packed area to hang out with friends. Friends all left and I stayed for a bit to admire the nature around the lake we were at. Go to leave and I notice it is digging down into the gravel rather than go over it, it's a pretty heavy vehicle after all so I didn't worry about it. Put it in 4wd and proceeded on my way. Drove it all told probably about 100 yards before I hit a deep patch of gravel. And the Tahoe just sank there was no getting it out. So I looked and the front wheels weren't even spinning at all! Ended up calling a relative to bring my 97 Dakota 4x4 (manual 5.2 V8) out to hopefully pull me free. Using the Dakota it took some doing but I was able to yank the heavy Tahoe out of the rut.

The Dakota performed flawlessly. I shifted into 4wd right when I needed it and it worked right away, none of this driving around crap before it would work. Made me love that little truck a bit more lol. Anyways back to the Tahoe.

Got the Tahoe yanked out and got it back on the road. And here came the next bit of annoyance. Put the Tahoe in N to shift out of 4lo back to 2hi, and according to all the lights it worked. But after a bit it became obvious that the 4lo had never disengaged. Now the front wheels never had power to them to begin with, but it was geared really low in the back now lol. So stopped the Tahoe, turned it off and turned it back on. Then put it back in N switched to 4lo again. Waited for the lights to say it was in 4lo. Then switched it back to 2hi. Worked this time and we were able to go home.

My main problem here is the front wheels not wanting to work 1/2 the time. I have been able to check and successfully have the front wheels working under their own power before, but it seems like when I really need it they just don't work. This suv has a habit of getting stuck in the snow around here too, because it does not want to engage the front wheels. I have really aggressive tires on it and it seems like they are going to waste because 1/2 of them don't get the chance to dig lol.

Anyways here are the mods, just in case someone is worried that that could be the reasoning. 31" tires, 2" leveling kit in the front (just a spacer), headers, flowmaster super 40 muffler, and I used a tuner to adjust the speedo for the oversized tires.

So basically hoping some people on here might have an idea why the front wheels don't work 1/2 the time, and maybe an idea on how to get the front wheels to engage immediately rather than have to drive it for a bit for them to work.

73shark

Don't have access to mine right now but what does your owners manual say)

SWHouston

I'm just going to take a wild guess here...

Sounds like your Transfer Case and Front Diff are sorta crudded/shellaced up. You might try a Fluid change on both. Once you do, you need to (just on dry surface) do several changes into 4hi and 4lo, and run it several hundred yards in each. Lots of times things just get gooped up, and doing several changes with fresh Fluid gets the system free to transfer.

aris_unlimited

Well I actually took it to the dealer today. It has been giving me fits for a year now, and I haven't been able to figure it out. So I bit the bullet and paid for the diagnostic fee. Turns out something is wrong internally on the front diff. It is jammed up and not allowing the gears to come together and activate 4wd. Not sure exactly what is wrong, because the minimum price they had (assuming it was a quick repair) was $400 for labor to drop the diff and crack it open, and then put it back. It could also have needed a complete overhaul, who knows. So I paid my diagnostic fee of $100 (which didn't really tell me a whole lot) and figured it is time to trade it in.

Tahoe was living on borrowed time anyways I figure. I never liked the 4wd systems in GM vehicles ever since they went to the electronic setups.

SWHouston

The more you tell about it, the more I think your Front Differential and Transfer Case are just shellaced up. A change of Fluid, will do wonders, but slow to transfer at first. Once you get it change once, don't quit there ! Do it several times where the fresh Fluid is circulated and cleaning up the sliders where it will shift properly.

Here's a "Rolling" Transfer procedure you might try after new Fluid and it starts changing to 4WD-hi.

Place Transmission in 4WD-Hi.
Accelerate Vehicle to just over 5 MPH.
Shift to Neutral Gear while moving.
As forward motion drops just below 5 MPH, Press 4WD-Lo button.
Transfer to Lo should take place within 10-20 seconds.

Other Information...
In some instances, you may have to use this "rolling" procedure to initially change into 4WD-Hi.
You many hear a respectable"clunk" upon transfer. (that's normal Chevy )
You may need to try the above procedure several times, for extremely sluggish Cases.
This procedure can be use for transfer in either direction (Lo-Hi/Hi-Lo).
This procedure should be done on Pavement or Hard Dirt, to allow the Vehicle to roll for a sufficient length of time.

Fluid Changes for the Transfer Case should be every 25K miles for severe use, and every 50K miles for normal use.
Exercising the 4WD-Lo function, should be performed at least once per Month, and driven at least 1 mile in 4WD-Lo to allow Lubrication to circulate.
Use AutoTrak II (or equivalent) for Fluid Changes (about 2 qts).

retsub

Maybe take it to Chapmans ask about a BG flush for it before doing any of the big repairs. *BW*

aris_unlimited

I suppose I should have put this bit of info in earlier. Year and a half ago, I had to change out one of the seals because it was leaking. Had to drain the fluid when I did that and give it all new fluid, so the front diff has fairly fresh fluid in it. And yes the 4wd worked after I did that, so it wasn't something I did.

I actually changed all the fluids, at the same time. So the transfer case is fine on fluid too. Also I can definitely tell the transfer case is working, and the actuator in the front diff is working according to the tech at chevy. The problem is (and he tried doing this manually) is the gears won't come together. His theory is that the fork in the front end is bad, but it could be a lot worse and I'm not going to sink more money into a car that might or might not fix it.

I have had 2 Chevy's since they switched to the electronic 4wd systems and both of those cars have had 4wd problems. Maybe Chevy's are just unlucky for me, either way I'm not going to waste more time and money on it finding out.