Haven't wheeled in a month or so, but we got snow the other day, so I wanted to use AWD. I felt a high rev off the start, and then the little beast launched (well, a 4D56 doesn't really launch, but I digress <img src="/forums/images/graemlins/smile.gif" alt="" /> ) with what felt like a slipping clutch, which makes me think its not locking.

Hubs are in locked mode, and it "feels" like its locked in 4loc, from my tests in the back alley the other night. Unless one of my hubs is not locking (I've got Aisin mannies on there), any suggestions as to where to start looking at the center vc diff unit? I have no "flashing 4wd light" syndrome, which is indicative of dirty solenoids and stuff. It goes in normal according to indicators, it just revs up as it very slowly starts off, as the vc bleeds off my engine's input - really feels like the hubs are unlocked... <img src="/forums/images/graemlins/confused.gif" alt="" />

Does the genII manually "lock" the vc for 4HLC and 4LLC when you select it on the t-case, even if active trac is not functioning, or have I missed the boat here? It certainly "feels" like 4hi is working.

BTW, 91 genII paj, 2.5TDi, 5sp, superselect/active trac, manual hubs, etc.

Phil

Phil, as far as I know yes; the center diff is mechanically locked when 4HLc or 4LLc
is selected. Of course, this then takes the viscous coupler on the center diff out of the equation.

Just one more thing: in my experience (based on some experiments with my old Gen 2) the viscous coupler does an amazing job of "locking" the center diff. It acts rapidly and solidly and does not slur at all. Also, viscous couplers normally fail to a state of almost complete lock-up. This is due to being overheated (e.g. By running different size wheels front and rear) and their internal plates distorting.

In the AWD mode, it should still drive off quite well even if the VCU had failed. I expect all your trail work has been in 4Low. This will not put a load on the VCU. This does not mean the PO was not hard on the transfer case before. Little hard for you to ask him.
If the CAD is not engaging you can confirm this by going into the Loc mode on the transfer, but as you write the lights say it is normal up there.

The 3000GT guys have been able to get their center VCU to puke the fluid out of the housing. It makes a major change to the gear oil but I never researched if the unit goes tight or opens with this failure.
The rally cars I work with can smoke the VCUs if they do allot of hand brake turns. Two drivers I worked with have repeatedly done so.
But then some people can break a crowbar in a sandbox.

VCU definitely goes to lock up on failure. It's extremely rare but I've heard of 1 or 2 failures on russian pajero club site. You can fail it by spinning your tires (or worse 1 tire) in 4H with diff unlocked for long time.

What do you need manual hubs for. I'd say one of them is possibly unlocked. I would check that quick otherwise it won't take long driving around to kill VCU thus to loose AWD. Once it fails you back to you regular part-time (which I guess is a good thing in a sense).

Phil this is the exact problem I've been having on and off for the past 10 months or so...except I have the flashing lights...when I let the clutch out I barely start rolling as if the clutch is slipping horribly. but I had a friend look and my front driveshaft is spinning. so I think my problem is my front diff actuator isn't engagine. and when I go to 4hi-LOC and 4lo-LOC, it drives fine but its still only the rear wheels powering the truck. I would check to see if when you launch from a stop in AWD if your front driveshaft is spinning super fast. you may have the same problem I do. and I can't figure out why my diff actuator isn't engaging

from my experience it sounds like your CAD unit being ghey,
i suggest eliminating is since you have manual hubs. you can do this by fabricating a replacement that is always engaged or buy a diff out of a gen 1 V6 or 2000-2004 montero sport, i used one out of a '04 sport.

The gen 1 is different being a low pinion. Your setup with the 04 diff may be the best way for the future.

I had forgotten about that, good looking out <img src="/forums/images/graemlins/kewl.gif" alt="" />

Alex, I put over 200kms on my truck most days, so if I can unlock my hubs and save a little wear on CVs during the summer months, that's a good thing.

Can't kill my VCU if I'm in 2wd. I'm not using it in AWD till I figure out what's going on. I did some more tests tonight, we got more snow, and it definitely feels like I'm not getting 4HLC or 4LLC either. Need to check the hubs. I recently had a seized caliper, which heated the hub - I wonder if it heated the grease enough to keep the hub's lock-ring from sliding up and down on its ramps?

If it wasn't so damn cold at the moment, I'd already have this gone through, but its much warmer to armchair wrench it at the moment, till the next chinook blows in (Monday its supposed to go from -21 up to 10*C.)

Thanks again for the diagnoses so far fellers. I'll report back.

Phil