occasionally it is known as "that piece of ****", or similar phrases 
.
.
Datatek
Well-Known Member
VCU Viscous Coupling Unit (NOT centre differential, sorry Ant) Jack one front wheel, you should, with a considerable amount of effort, be able to turn it. If it doesn't turn the VCU is seized which will cause transmission wind up
aerofabrique
Active Member
it might be stating the obvious but all your tyres are the same size and you don't have any flat spots on your front ns caused by either standing too long or heavy braking and locking up caused by say..towing?
Brake caliper pins are free and working not causing them to seize on?
No play in the shocks and bushes and mounts on both front shocks are secure?
Brake caliper pins are free and working not causing them to seize on?
No play in the shocks and bushes and mounts on both front shocks are secure?
Datatek
Well-Known Member
Datatek
Well-Known Member
A bit of free movement front to back is normal, it should continue to turn after the slack is taken up but it will be very hard. Yes box in neutral but you can leave the handbrake on.
But doesn't it act like a Centre Diff without actually being one!!VCU Viscous Coupling Unit (NOT centre differential, sorry Ant) Jack one front wheel, you should, with a considerable amount of effort, be able to turn it. If it doesn't turn the VCU is seized which will cause transmission wind up
(And I did decypher it as the Viscous Coupling Unit
)
Datatek
Well-Known Member
But doesn't it act like a Centre Diff without actually being one!!
(And I did decypher it as the Viscous Coupling Unit
Nope, it acts as a centre diff lock on the P38 which has a proper centre diff, unlike the Xtrail for example which uses a VCU instead of a centre diff
Oh feck yeah - as soon as I read the first 6 words it dawned on me - I am such a ****...!!!Nope, it acts as a centre diff lock on the P38 which has a proper centre diff, unlike the Xtrail for example which uses a VCU instead of a centre diff
If it won't move at all beyond the natural slack take up - the VCU has seized, this will cause the 4 wheels to try an rotate at the same speed and cause scrubbing and jerky when trying to turn corners....
That would mean a new VCU is required - ££
If it turns really slowly with a good amount of effort the VCU is probably fine.....
I am not sure if a seized VCU would cause oscilating up-down movements at the front end though...!!
That would mean a new VCU is required - ££
If it turns really slowly with a good amount of effort the VCU is probably fine.....
I am not sure if a seized VCU would cause oscilating up-down movements at the front end though...!!
It's a steady pressure you need to test it. Removing front prop and going steady should be ok.
Datatek
Well-Known Member
Only guessing, but depending on load distribution, I reckon a seized VCU could cause bouncing as the transmission unwinds over minor bumps in the road.
