Effects of vacuum on 4wd.

[scrubber3]

What are the repercussions of not having enough negative pressure(vacuum) on the four wheel drive system? What about a faulty vacuum actuator? Signs/symptoms? Gen 2 of course(95).

[Monterorider]

vacuum disengages front axle disconnect. So if you don't have vacuum you will have permanent 4WD. Smartly done by Mitsubishi since if you loose a tube in a bush you will have your 4WD system functioning. With center diff won't matter much on pavement.

[Monterorider]

Many moons ago I made a post about it in other forum How active track disconnect works

[scrubber3]

vacuum disengages front axle disconnect. So if you don't have vacuum you will have permanent 4WD. Smartly done by Mitsubishi since if you loose a tube in a bush you will have your 4WD system functioning. With center diff won't matter much on pavement.

So theoretically if I have manual front locking hubs, I can disengage this system without any ill effects?

What could be a cause of a sudden disengagement of the drive train when in any 4wd mode when applied a load to. It is not the transfer case, though this has caused the destruction of one transfer case already. 2wd is fine. When it disengages, it produces a horrible grinding noise. If I had an exploded view of the transfer case innards and where it ties into the transmission, I'd be fine to figure it out.

Any help is welcome and let me point out that my montero, even without 4wd is a beast off road. Granted the rear locker helped.

[Monterorider]

So theoretically if I have manual front locking hubs, I can disengage this system without any ill effects?

If you are careful about it. If you have your front wheels disconnected but engage 4Hi in transfer. All of the engine torque will travel vi viscous coupling to rear wheels. It wheel burn it out in no time which effectively will lock up your center differential and make your truck part-time 4wd only. How do you tell "disengagement of the drive train when in any 4wd mode" what do you mean by that

[Monterorider]

Here is some info I've posted on innards and workings of t-case internals

[scrubber3]

If you are careful about it. If you have your front wheels disconnected but engage 4Hi in transfer. All of the engine torque will travel vi viscous coupling to rear wheels. It wheel burn it out in no time which effectively will lock up your center differential and make your truck part-time 4wd only. How do you tell "disengagement of the drive train when in any 4wd mode" what do you mean by that

Upon shifting into any position other than 2wd and applying a "load" upon the drivetrain, there is a noticeable disconnection of the entire drivetrain and a grinding noise. The vehicle doesn't move and grinds until placed in neutral of course. Upon letting everything stop spinning, place into 2wd. Once that engages fully, I can apply all the load I desire without any ill effects. It shifts into 4wd and will act fine until I start up a hill or over rocks or give the accelerator a good push from stop. This is when it "comes out" and proceeds to grind and doesn't progress anymore.

I am under the impression that the vacuum/vacuum actuator may be responsible for this pending the vulnerable position of the actuator and the fact that when it happen the first time with the old transfer case I had just got through some major rocks and tree limbs. One limb which was responsible for tearing my new cv axle boot.

[LaOutbackTrail]

I'm interested to see what you guys conclude.

[Monterorider]

Are you shifting past 4Hi into 4Hl or 4Llc. Hubs engaged? If former sounds like your chain is broken, stretched or slips or some other t-case innards damaged. Gen 1s were know for chain issues but Gen 2 are pretty stout. People wheel it with 37's and low gearing. There is always a possibility of some hidden defect of course. Ask somebody to look under your truck when grinding happens. If front drive shaft spins then - it's front axle if not - t-case. If it's axle it could be broken diff. There is really not much to break in actuator.

[Monterorider]

it has got to move forward in 4Hlc or 4Llc because it's part time mode. So it tells me you are only engaging 4H. Put front on jack stands. spin wheels, listen for bad sounds from diff. Everything rotates as appropriate? Put in in 4H lower one side (or ask somebody to hold opposite wheel) . Transmission in N check when you spin driver's side wheel that drive shaft rotates. If it does listen for sounds in t-case.