GU/ Y61 GR SE RD28T shut down

[Telemark]

So i have this RD28T, this morning i went out to start up the GU to unfreeze it before i go to work, but after a few minutes it stops, and now it won't start at all, i'm not sure what it is, but i know it has been leaking oil for some while, so it might be loss of oil pressure. What do i do? And if the engine is completely fu**ed, how hard is it go get a GQ 2.8 in it? Thanks for answers

[Wine_maker]

If it stops suddenly, without any noticeable unusual sounds, first of all, you should check the timing belt.
It's placed under the black cover in front of the engine and it is mounted by 4 or 5 bolts, so it will be easy to check.