Lack of torque at front wheels

[zlumax]

First of all, greetings from Slovenia! Not a natural habitat of any Hummer, so support at local mechanical shops is virtually nonexistent. I've recently bought a 2006 H3, 3.5 i5, VIN 5GTDN136968246413. Not sure about the package, as it has heated leather seats (which i think are part of a lux package) and rear locker, which i thought are telltale sign of adventure package.

My problem is with the offroad ability/behaviour. While the rear locker works fine, i thought the traction controlled brakes apply brakes to the front spinning wheel, transfering torque to the wheel with grip. In some moderate offroading i did in the previous days i figured out the front wheel keeps spinning, without any torque transferered to the wheel on the ground.

I've done more tests today. It turns out, in some positions while in 4Low and rear locked, NONE of the front wheels are turning while both the back ones are spinning.
If i understand this correctly, 4LOW = middle differential locked = 50/50 front/rear distribution, so at least one of the front wheels should spin at all times, is that correct?

If that is the case, what can be the problem? In some wheel positions one or both of the front wheels spin, but in some positions i've caught the back two spinning and front two only twitching.
Initially i thought it might only be a traction control problem, now with observing a situation where none of the front wheels had any torque, i am not so sure anymore.

There are no messages pointing to the faulty TCS, stability is turned off as i shift into 4LOW. No dash messages pointing to any system, lights indicate successful engagement of 4High locked, next 4low and Rear locked.

I've tried searching the forums for some conclusive information on the topic, but were unable to find any, so any and all help would be much appreciated!

 

[zlumax]

Furter tests revealed that TCS system works as intended, and what is not working is locking the middle differential (in transfer case?). When going from 4Hi to 4Hi locked and to 4Low there is no problem, Transfer case shifts to low gears and all. There doesnt seem bo be any middle lock tho. Performing sharp turns produce no rubbing/skipping of any wheels and no binding felt in the stering wheel like i experienced in other four by fours.

Can the problem be caused only by a bad transfer case fork? Should i go on and order one before seeing what is inside the TC?
I have limited options and want to optimize the times the car will be at the shop, and i need to come with the knowledge beforehand as there is no specialists near me.

 

[alrock]

Welcome! Sorry about the issues and thanks for the good details and troubleshooting.

It sounds like you have both optional packages: Luxury and Adventure.

If the transfer case is going into 4 low, it's not likely the transfer case shift fork. The fork controls the modes, and it's changing modes, so it appears the fork is working well. Could there be a different issue in the transfer case? Yes, but it's not the most likely issue.

The traction control is not perfect. It will, to a point, apply brakes to a spinning wheel to keep power to a wheel with traction. This generally works only at low RPM/speed. To get it to engage, you'd be "stuck" with one wheel not getting traction. You'd keep on the accelerator with a light press while the wheel(s) spin, and a few seconds later the traction control will engage, But at a minimum you should see one front wheel spinning if the other three tires have traction and you should see them spinning if you were trying to power through something like sand.

The issue is likely with one of two systems: a broken CV axle at the front wheels, or a broken front differential. Inspect both front CVs for damage. For the front differential, I would recommend draining the oil and looking for metal in the oil. Better yet, if you can, pull off the front cover after draining and inspect it. Can you do these things yourself before taking into a shop? If not, I'd have them start there.

Similarly, I would go ahead and drain the transfer case to ensure the fluid is reddish and not silver like the Terminator. Also, look for the very obvious that the front propshaft is in place, is intact, and is spinning when the H3 is on a hoist and the vehicle is put into Drive. It should spin in any of the 4wd modes. If it is not, then you may have a transfer case issue. You could also verify this by attaching a GoPro underneath and going for a drive.

Fluids are 75W-90 for the differentials and Dexron VI for the transfer case. (Your owner's manual may say Dexron III but the tech manuals were later updated to say Dexron VI as Dexron VI had not yet been certified for the 2006 H3 when the manual was printed. It was later certified for Dexron VI.)

 

[alrock]

Actually, the more I think about it, I'm a bit stumped. If there was ZERO drive at the front wheels then the truck would not likely move forward at all in 4 high unlocked mode. Or maybe I'm over thinking it. Either way, I would definitely check those fluids for metal. It could be something else in the transfer case that's allowing it to get into 4 low but not transferring power to the front wheels.

 

[zlumax]

First of all, thank you so much for taking the time and writing all this, alrock!

I've optimistically already went forward and ordered the fork, but maybe in vain? Is locking the center diff and changing from high gears to low gears part of the same functionality, or same set of parts?

Concerning traction control, i've done more tests - we put the car on the lift and cycled trough the different modes (4hi, 4hi locked, 4low, back locked). Nothing behaved outside of what i expected it to. Granted, there was no load and that for certainly doesnt provide for the best testing environment, but holding one or the other of the front wheels consistently engaged traction control in all modes and torque was transfered to the stationary wheel via braking the spinning wheel. That makes me believe the front propshaft (it was indeed spinning in all the modes), as well as both CVs are OK? One of the inner CV sleeves is puking grease, that is something to be looked at for sure, but while trying to hold the wheel, to see how traction control behaved, there was torque on it for sure (some at least, enought to move a puny human trying to hold it down).

Together with these tests i've changed the front differential oil, expecting to see a festival of metal shavings - there was nothing. Good looking oil, fished in it with the magnet, nothing. That makes me believe front differential is OK, sadly wasnt able to look into it though.

If beforehand I didnt perform a few tight circles in the parking lot with (supposedly) 4hi locked and 4lo (locked?) without any binding or wheel skipping, all would lead me to believe everything is A-OK.

I have 2 liters of Dextron 6 ordered, which ill be able to drain and refill in the upcoming week. Apart from that i'm quite lost. 3 owners, 180000km and absolutely zero offroad kilometers on the truck before i got it, and i get it without a working offroad parts.. .