Sorry, it's me again.
Still got my head stuck in this engine.
Is it possible to have a leaking front main oil seal without any oil appearing on the belts or the casing behind the main pulley?

I am sure that is a stupid question, but my belts are dry and the front of the engine id bone dry!
It is definitely coming from above the oil-pan / sump and running down.
I am considering taking out the drive shaft to get a better view of the side of the engine.

 

If you didn't find oil on top of the engine, then the problem is not what I suggested. Definitely pursue the other things that others have suggested. Cleaning the engine is a good start.

 

FOUND IT.
There is a pan-head splined screw above the drive shaft mounting bracket with a copper washer - it was loose.

I found it by stuffing kitchen towel everywhere I could an watching (after removing the drive shaft and bracket) !!
Thanks everybody

 

That sounds like the main pressure feed line for the turbo. Good thing you caught that, it could have pumped all of your oil out of the engine in about 10 seconds.