1973 Land Rover Series 3 oil coming up threw the breather cap sides

Check engine breather / PCV valve is venting o.k and not restricted as if blocked it will build up excessive back pressure . If not that may be internal engine problems

Thank you
I have cleaned out the gauge mesh
The hose coming off the breather cap is sucking
BUT the oil is not going up the base as it should

If you are blowing blue smoke also it's likely to be wear on the bores / piston rings

White smoke

White smoke can occur on a diesel when either there is an injector fault , engine coolant is entering the combustion chamber, or worn, pistons or other components . If coolant it will usually pressurise the cooling system .