Thanks, I will do another test on the Weekend and then see...
New VC seem to be very expensive, does ist make Sense to go for a used Transfer Case ? They are a around 300-400 Euros here in Germany...
Seized VC: means front and back axle are locked or also left/right ?

If the VC has seized it means the front and rear axles are locked together and will always turn at the same speed. The usual symptom is when you pull away from a standstill with the steering on full or near full lock one way or another, the front wheels will try to skip sideways. This is because the front axle should be turning at a different speed to the rear.

OK, so I chekced again. Jacked up one front wheel (Gear in P) and there is now way I can get it to turn in any way.
When I pull away with the steering full in one direction I do not get skipping wheels but a clunk noise front the front left (CV Joint?) and sometimes the TC kicking in, but that may be because it is not dry anywhere here...
What it does have is quite some free play so that at the circumference it´s about 10 cm (4 Inchens). Is taht normal ? Comes form the diff, right ?
So is the worst case scenario worn diff + broken CV joint + seized VC....?!?
I feel like Don Quichote with this car....

The free play is in the diff and is quite normal. When checking the Viscous Coupling, this is the process for doing it at the output shaft flange. Doing it at the raised front wheel will be the same but the angle will be different due to the diff ratio. This is from the Ashcroft Transmissions website.
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Viscous unit - rolling resistance Bench check NOTE: Testing should be carried out in an ambient of 20 deg C.

1) Secure the output shaft ... (this will be done by the gearbox being in Park or the Parking brake being on.

2) Apply a clockwise torque of 27 Nm to the (front propshaft) output flange nut. If no resistance to turn is felt, unit requires replacing.

3) If resistance to turn is felt, apply a clockwise torque of 20Nm to the (front propshaft) output flange nut for 1 minute, this should result in a rotation of approximately 25 deg - 30 deg. If no rotation or a greater force is required, unit requires replacing.

27 Nm = 20 lbf-ft 20 Nm = 15 lbf-ft
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If you've got slack in a CV joint that might be enough to allow the wheels to not skip.....

Just one though.

I would think that if in Park AND rear prop secured (handbrake or both rear wheels on the ground) you should not be able to move the front prop regardless of if VC is seized or not?

I kind of think it's possible to understand #18 so that no movement would mean VC is seized.

But I might be wrong of course, wouldn't be the first time.

th.

You will. The VC slips very slowly to allow the slight variation in speed between front and rear axles when cornering. If a wheel loses traction so the difference in speed between the two halves increases, then it locks. That avoids the need for a locking centre diff as it does it for you when required.

OK, I'll Check again on the Transfer Output Just to be Sure, have ti Take Out the proshaft anyway, now with a better tool....

OK, so took the propshaft out again (with the new tool, but that is only really useful on two of the four nuts), tried turning the nut on the transfer case output as described in the proper test method and there is no way I can move it. So I guess a replacement viscous coupling. Since I am getting a bit wayr which probelms the car will throw at me next I guess I will go for a used one fron the UK, as here in Germany you can only get used transfer cases....let´s see....
This car is like a tough Zen master......!

Was the gearbox in neutral when you checked?

th.

It won't matter, you are checking for movement between the front and rear propshaft outputs. So you want it to be in Park with both rear wheels on the ground and/or with the parking brake on. That way the rear output can't move and, if the viscous is good, you should be able to move it slowly. If it isn't possible to turn the front output while the rear is locked, the viscous is seized.

If you can move the front with rear and gearbox blocked then there is definately something wrong.

The transfer case is diff, and as with any other diff, if you can move one end with the other two blocked, something is wrong. The viscous coupling is there to provide diff lock.

As Ashcroft Transmissions put it:

"A common problem with the Range Rover BW transfer case is a “seized viscous coupling”. This can easily be identified by the effect it has on cornering, the tyres will “chirp” or “scrub”, as the vehicle is effectively permanently in diff lock. As a confirming check, put transfer case in “neutral”, handbrake on, jack up one front wheel and try to turn it, it should turn slowly with resistance, if locked solid the viscous coupling is seized, and will need changing before any damage to the diffs or CV joints occur."

They provide more detailed info in the technical part (as you quoted), here without any additions:

1) Secure the output shaft …

2) Apply a clockwise torque of 27 Nm to the (front propshaft) output flange nut. If no resistance to turn is felt, unit requires replacing.

3) If resistance to turn is felt, apply a clockwise torque of 20Nm to the (front propshaft) output flange nut for 1 minute, this should result in a rotation of approximately 25 deg – 30 deg. If no rotation or a greater force is required, unit requires replacing.

Note that in 1 they say output shaft (secured with handbrake or possibly both rear wheels on the ground and choked), not mentioning the gearbox.

th.

Yes, that is correct. If you look at how the transfer case works, direct drive from the gearbox goes the the rear output while the drive from there goes to the front via the viscous coupling. So you are only checking the bit between the two outputs.

It's quite common that people misunderstand how the bw transfer case works, there is a good diagram here:

https://www.4x4community.co.za/forum/showthread.php/249882-P38-Vibration/page2

And some discussions here on the other side

https://www.rangerovers.net/threads/p38-driving-with-rear-prop-shaft-only.356996/

The front drive goimg via the vc is misleading as it does not go through the vc itself, but the outer part of it.

th.

Mirafiori-Max wrote:

OK, so took the propshaft out again (with the new tool, but that is only really useful on two of the four nuts), ...
This car is like a tough Zen master......!

The tool is fine (and easier than a standard socket) on all four nuts if you just turn the prop shaft so it's at a sensible angle.

They way I did it was two left wheels off the ground (otherwise no chance to move the propshaft), Gearbox in P and handbrake on. Then turn on the front output of the TC.
Does that qualify ?!?

Yes, if you were able to turn the front output, the viscous is OK, if you couldn't, it's seized.

If the handbrake is holding and with gearbox in P it would only turn if the transfer case is broken.

th.

Ok, reading though everything again and understanding the diagram (and I think both Richard and Thorst are right in a way) I believe the way to test it is to put the transfercase into the "towing neutral". I did not do this, I put it in P+handbrake. Otherwise turning the front output as I did cannot possibly turn as front and rear are mechanically locked by the output from the TC to the centre diff. If the gear at number 9 of the diagram does not move, the other three cannot either, right?
I will try the same again with the Fuse in to put the TC in neutral. That should make all components inside the TC before the centre diff moveable...

Even when the TC is in neutral I cannot turn the front output. Both rear wheels on the ground. It does not turn independent of the rear one, it is as if they were connected. So it must be seized.

Mirafiori-Max wrote:

Even when the TC is in neutral I cannot turn the front output. Both rear wheels on the ground. It does not turn independent of the rear one, it is as if they were connected. So it must be seized.

Correct. Transfer neutral disengages the input from the gearbox. You simply need to lift one or both rear wheels, and then you can turn the front prop for easy access to the nuts with the correct tool.

My VC was quite stiff, but I could certainly move if fairly easily with socket & 2ft breaker bar. Very hard to turn with a standard ratchet though.