Zetor 14145 engine oil pressure

Hi lads
I've just rebuilt the 14145 engine after head gasket failure. It's got new main bearings and con rod bearings as well as an oil pump and relief valve.
When the tractor starts cold the oil pressure is just over 4 bar but when hot it drops to just over 2 bar.
Is this normal?
Does anyone have a 6 cylinder? If so what's the oil pressure at when the engine is hot?

those pressure's are ok [ 30-60 psi ]

where u are loosing pressure when hot is most likely from the camshaft bearings.