16.8mpg from a P38?? Hmmm....

A long breaker bar should do it if you used the torq wrench ignor clicking at full tension and carry on if you can turn wheel it's fine but it will feel very stiff

NikTheGeek said:

Ok, done a VCU check. Well..... it depends what you mean by a lot of effort. I'm only a 10 stone weakling but I couldn't move the wheel with my hands or even with the supplied wheel wrench. I could if I stood on the wheel wrench, but it would only move a little. When I put my torque wrench on it, I could move it then but even on its maximum setting (140lbs) it was clicking to say I was over-torquing. But at least I could move it.

That ok? Or not...

Nik

Click to expand...

If the wheel actually turns with a constant pressure the VCU is OK

Datatek said:

If the wheel actually turns with a constant pressure the VCU is OK

Click to expand...

Nope, tried again. It doesn't. With 140lbs I can turn it a few inches, but it won't keep turning. After a few inches I can't turn it any more.

Assuming I can find the part (which seems surprisingly hard) is it DIY'able?

tnx

Nik

140 lbs isn't that much in the greater scheme of things. I wouldn't write it off yet but Wammers, SaintV8 or Datatek are probably the best for knowing how much force it will require.

Borg Warner Transfer Box Testing (VCU)

To test the VCU (Viscous coupling unit) in a Borg Warner transfer box, the following test should be carried out:

1. Apply the hand brake
2. Jack up one front wheel
3. Using a torque wrench apply 60 lb/ft of torque to a wheel nut
4. The wheel should rotate through 90° in 60 seconds
5. If it will not rotate the VCU is siezed
6. If it turns freely most likely the diff is damaged or a half shaft is broken - probably caused by a siezed VCU

Ok, lets assume that the VCU is knackered and this is causing my poor MPG. There's a simple way of testing it: remove the prop shaft so it's rear wheel drive only - if things improve a lot, then I know I need the VCU done. Other symptoms I have that forums say could be the VCU are a shake at 50-60mph that feels like the wheels are out of balance and the brakes squeaking like they are on, but only when reversing.

Anyway, how do I disconnect the prop shaft? I assume it's an easy and quick job, but any pointers?

I do hate not having a book to look up.

tnx

Nik

good idea - better to be safe than sorry .

Test for VCU. Apply 20 pounds feet to output shaft of VCU for one minute. Flange should turn 90 degrees in that time. So if you do it at the wheel apply 70.8 pound feet to the centre drive shaft nut for one minute, in that time wheel should turn 25 degrees. Trying to turn VCU too quickly with too much force will cause it to lock. 20 lb ft x 3.54 (diff ratio) gives 70.8 lb ft. 90 degrees / 3.54 gives 25 degrees of wheel movement to move output flange 90 degrees. Simples.

Wambo - that is a lot different from what i found

From our friends at Ashcroft....





You can either do this test on the bench or in the car with the handbrake on and one front wheel lifted.
Viscous unit - rolling resistance Bench check NOTE: Testing should be carried out in an ambient of 20 degC.
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? - 30?. If no rotation or a greater force is required, unit requires replacing.
27 Nm = 20 lbf-ft 20 Nm = 15 lbf-ft
Installation Instructions

How to fit a viscous coupling unit
1) Remove front prop shaft
2) Drain oil from transfer box
3) Support gearbox and remove right hand gearbox mount
4) Remove bolt holding Viscous Coupling housing to transfer box
5) Rotate, to break silicone, and remove Viscous Coupling housing
6) Remove flange nut and flange and press out Viscous Coupling
7) Clean all joint faces
8) Replace Viscous Coupling and reassemble in reverse order

I can turn the front wheel on mine just by gripping the tyre and keeping a constant force on it, but I'm pretty strong.

Datatek said:

I can turn the front wheel on mine just by gripping the tyre and keeping a constant force on it, but I'm pretty strong.

Click to expand...

Had another go. If I turn it in the direction it would turn when going forward, I can turn it by sitting on my torque wrench (feet still on the floor). It does turn and starts to get easier once its going.

Where I was going wrong before was turning it the other way AND turning it too hard and fast and it didn't move. Turn it slowly and it does move - but its still quite hard to move and required me to sit on it - but like I said, not my whole weight, just resting my bum on it...

So I reckon its working. The question is, is it past its useful life and should I replace it anyway?

Cheers all

Nik

The Mad Hat Man said:

Land Rover Owner • View topic - Borg Warner Transfer Box Testing (VCU)

Click to expand...

That method would mean the output shaft turning 318.6 degrees in a minute. Don't think you should take much notice of that one. The VCU would have to be totally knackered for that to happen.

NikTheGeek said:

Had another go. If I turn it in the direction it would turn when going forward, I can turn it by sitting on my torque wrench (feet still on the floor). It does turn and starts to get easier once its going.

Where I was going wrong before was turning it the other way AND turning it too hard and fast and it didn't move. Turn it slowly and it does move - but its still quite hard to move and required me to sit on it - but like I said, not my whole weight, just resting my bum on it...

So I reckon its working. The question is, is it past its useful life and should I replace it anyway?

Cheers all

Nik

Click to expand...

If it's turning it is ok.

NikTheGeek said:

Ok, lets assume that the VCU is knackered and this is causing my poor MPG. There's a simple way of testing it: remove the prop shaft so it's rear wheel drive only - if things improve a lot, then I know I need the VCU done. Other symptoms I have that forums say could be the VCU are a shake at 50-60mph that feels like the wheels are out of balance and the brakes squeaking like they are on, but only when reversing.

Anyway, how do I disconnect the prop shaft? I assume it's an easy and quick job, but any pointers?

I do hate not having a book to look up.

tnx

Nik

Click to expand...

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NikTheGeek said:

Ok, lets assume that the VCU is knackered and this is causing my poor MPG. There's a simple way of testing it: remove the prop shaft so it's rear wheel drive only - if things improve a lot, then I know I need the VCU done. Other symptoms I have that forums say could be the VCU are a shake at 50-60mph that feels like the wheels are out of balance and the brakes squeaking like they are on, but only when reversing.

Anyway, how do I disconnect the prop shaft? I assume it's an easy and quick job, but any pointers?

I do hate not having a book to look up.

tnx

Nik

Click to expand...

geez if you can't take a simple tube with 8 bolts off best get help.

When had my v8 the mpg on the trip would never rise above 13. even when i calculated i was actuallt getting 15. And the average speed never went above 26 no matter how long was on motorway etc after reset it.

greenslade said:

Thanks for this thread - it is making me feel a whole lot better about running a 4.6 V8 lol

Click to expand...

My thoughts exactly.

JamesBB said:

My thoughts exactly.

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Don't feel too smug, if your 4.6 was doing the same cycle you would be in single figures. Consumption depends on duty cycles and the topography of where you live.