HZJ75 Transfer case 4x4 doesn't engage (1 Viewer)

[AfricaPhil]

Good evening from Rwanda,


I am living in Central Africa since a couple of years and bought a landcruiser HZJ75 troop carrier a couple of months back, 1HZ of course, 1996 model.


The car has spent 300.000 Km on African roads and was fixed / maintained by local garages for her entire life. Meaning: The car was a complete mess when I bought it. But I am spending my weekends working on her and slowly getting somewhere.


But the 4X4 / transfer case is giving me headache big time.


When I bought her, the 4x4 did not work and hadn’t been used for ages. As there were heavier problems with the truck I did not see it as a focus until a couple of weekends back. What I found out since:


There is underpressure coming through the valves to the tubes connected to the Diaphragm Cylinder. After having cleaned it for 5 hours the Cylinder works. Meaning: if I dismount the cylinder from the transfer case and connect the tubes, I can see that the shift link lever moves from left to right according to pressing the 4x4 button in the cockpit. It moves very slowly though. Takes like a 30 seconds to completely move from 2x4 to 4x4 position (how long shall it take?).


But: If I mount the Diaphragm Cylinder to the transfer case it doesn’t move the Front Drive Shift Fork Shaft from 2x4 (meaning shaft in “inner” position) to 4x4 (meaning shaft coming out of the transfer case). If I manually move the shaft, it works and 4x4 engages. But it takes some force to move the Front Drive Shift Fork Shaft manually (hammer and chisel).


As the Diaphragm Cylinder moves very slowly / weak and the Front Drive Shift Fork Shaft doesn’t move easily, I am not surprised that it doesn’t work.


Question: What could be the reason? And what the solution?


Sorry: English is not my mother tongue! Hope you get what I am saying.


BTW: She changes from H to L, so that at least works.


Hope you guys can help!


Cheers


Philipp

 

[roscoFJ73]

Sounds like a lack of usage is the main problem, combined with a lack of vacuum. They should move in or out of 4x4 in a few seconds.
Check the vacuum lines back to vacuum pump on the front of the engine. You maybe better off replacing all the rubber hoses.
Maybe you could pressure test them in water and look for bubbles.
The vacuum pump doesn't usually cause problems

But it takes some force to move the Front Drive Shift Fork Shaft manually (hammer and chisel).

Spray it with lots of WD40 or something similar. Get all the rust and dirt off.
Does it change faster if you are moving?

 

[roscoFJ73]

But: If I mount the Diaphragm Cylinder to the transfer case it doesn’t move the Front Drive Shift Fork Shaft from 2x4 (meaning shaft in “inner” position) to 4x4 (meaning shaft coming out of the transfer case).

Try swapping the 2 hoses around. This will make the button on the dash work in reverse, but its good way to diagnose the problem. It could be one of the vacuum solenoids.

 

[AfricaPhil]

Many thanks for the answers.

Just a very simple question: Is it possible to change the 4x4 air (under pressure) system to a manual system? Meaning moving the Front Drive Shift Fork Shaft not through the air system by pushing the 4x4 button in the car, but by the transfer case stick? I know that older land cruisers were completely manual.

That would actually be my preferred option.

 

[GTSSportCoupe]

Many thanks for the answers.

Just a very simple question: Is it possible to change the 4x4 air (under pressure) system to a manual system? Meaning moving the Front Drive Shift Fork Shaft not through the air system by pushing the 4x4 button in the car, but by the transfer case stick? I know that older land cruisers were completely manual.

That would actually be my preferred option.

Yes, guys have done this. Check the 60 series section. The late 60 series had vacuum transfer case too, and they have documented swapping the vacuum actuator to a regular shifter.

 

[roscoFJ73]

Is it possible to change the 4x4 air (under pressure) system to a manual system?

Yes ,but the vacuum system is usually very reliable. Its usually the manual system that has trouble shifting into 4wd from lack of use.
IMO you are better off getting the vacuum system working. One advantage is you can shift into 4wd at a much higher speed