this odour may be because it is newly fitted or you didn't fit it properly
try the head gasket.
It is there to stop the fluids and compression from leaking out.
Damage. Hole. Perished gasket. Incorrectly fitted. Corrosion.
there arnt any hoses coming from the head gasket
If fumes are coming into a car it is most likely not going to be coming from a head gasket. The more likely places will be a blown exhaust gasket, exhaust doughnut, or some other type of exhaust leak.
the head gasket needs replaced.
If it has been fitted correctly then there should be no problem.
All head gaskets are located between the engine block & the cylinder head. In theory you do not need a head gasket if the head and block are perfectly machined but in practice, a gasket is normally fitted as the cost of such engineering would not be cost effective Best wishes
Replace the thermostat gasket.
Pretty much has to be a blown head gasket.
You may have a blown head gasket.
there is no water mixed with the oil but have antifreeze coming out of the exhaust