Hi,
Servicing the 4.4 TDV8 last night and in the process of cleaning up dropped some degreaser on the serpentine belt which threw itself off on starting.
Ive been looking for a "how to" get it back on and will probably replace it for the effort.
Does anyone out there have a step by step for how I can go about this please?

By taking the drivers side air filter out I can get a socket on the nut above the tensioner which I had thought would open it up to allow the belt to go back on it however its obviously not the tensioner.

Help appreciated. Car immobile obviously.

Item 11 is the tensioner pulley. Put a socket on the hex nut cast as part of the tensioner housing, rotating it clockwise to allow the back of the belt to be slipped off/on the smooth pulley 9. You will need an extension on the socket handle to get enough leverage to pull and hold against the spring in the tensioner.

If you need the fan stretch belt of of the way to R&R the serpentine belt, there is no need to cut it as it can easily be run off with a screw-driver but will need a small clamp (I use a very small G-clamp) to clamp it to the crankshaft pulley to then rotate the crankshaft to run the belt back onto the fan pulley.

Thanks Graeme.
Not the easiest of jobs!

Traditionaly replacing the belt involves removing the fan and shroud to get enough access. If it's slipped off so easily it may also point to wear in the tensioner. 2012 TDV8 Vogue (L322)

Thanks JayGee,
You were spot on. It was the tensioner. It had lost its mojo and its resultant angle had only half the belt on the pulley.
Lucky it happened in the driveway.
New tensioner and pulley, serpentine and stretch belt installed. Good as new.
Thanks for the tips everyone.