A160 W168 2001 Model (petrol) - Oil pump not pushing up to head / rockers

Hey guys...I am at a total dead end... In short my A160 broke a timing chain...So moral of story is...Cylinder head to be skimmed, new valves was put in, new oil pump (and was primed with new o-ring in it), new tappet on lifters were replaced...(luckely pistons was all still ok). So after re-assembling of engine the car started but way too loud and almost sound like a diesel...I then noticed that oil does not reach the cam/lifters and the new oil filter stays dry...So the oil pump is not pushing oil up the tube to the cam area.... How do I prime Oil pump without taking out the engine again or is there something else that I'm missing? The oil engine light does go off in the car after a few seconds after car is started. I hope someone understands all this and can give me some valuable advice what I could do.