Thread: 300 Tdi NO oil pressure ??

Hoping someone has had this problem before and it was something simple

300 Tdi (in def 130) had just driven 25kms from town home to farm all seamed fine (good even)
switched engine off 15 mins later restarted to go out (warm start obviously)
oil pressure light stays on?? ??? (never seen that before) and YES it was full of oil (I had actually just checked it)
turn off engine, think a while, think maybe oil pressure sender ??
muck about in shed, find some fittings and oil pressure gauge, remove sender and hook up gauge
restart end NO oil pressure (nada, nothing, zip zero) gauge doesn't move off bottom stop ?

Call friend (LR mechanic) with trailer, to take car back to his workshop
trying to think of possible causes? maybe oil pick up broken ?? remove sump nope (bugger) all looks ok
can't think of any thing else simple that could just happen without any warning??

any clues??

looking for help
thanks
Jase

PS possibly related, I don't think so (but worth mentioning anyway)
I had just picked car up from my mate (LR mechanic) in town and had driven home (the 25kms above)
he had just had the head off cause it did a head gasket, while he had it there I also had him do timing belt cause it was also
almost due, I was thinking if it could be to do with oil pump drive but he didn't remove the bottom timing gear so I can't see how
he could have disturbed it ??

any clues

thanks
J

pressure relief valve stuck open with a bit of debris from the head job ?