The cooling systems of diesel and gasoline engines fulfill the same purpose and are very similar in terms of operation and composition of their parts. However, both maintain a big difference and it is the method of cooling the coolant. 

And it is that gasoline engines use a fan to cool the coolant , unlike diesel engines, which perform cooling through the ducts that come out of the radiator and heat exchanger

Thus, the elements of the cooling system of a diesel engine are more resistant than those of gasoline , since they withstand more pressure and temperature.