It could be the radiator cap is lower than high point of the cooling system. In that case there may be a bleed plug at the top of the engine.
Probably an air-lock somewhere !
Usually there is a valve that you can open to let the air out .
because oil filled radiators transfer heat more effectiantly
Trapped air pocket.
The Bugatti Veyron has a total of ten radiators.3 heat exchangers for the air-to-liquid intercoolers.3 engine radiators.1 for the air conditioning system.1 transmission oil radiator.1 differential oil radiator.1 engine oil radiator.
Gas heated hot water radiators.
yes
Bleeding the air from them usually helps.
The acronym for Air Lock is A/L.
No radiators work best by allowing air flow to rise through them, a small fan will be better.
On/Off valves in radiators turned off or clogged Another possibility is an air bubble in the loop that services the radiators that are not heating. Correction is to bleed the loop.
That is for the air can flow through the radiator and cool the engine coolant down.