I have a 1990 929 Mazda: Temp Gauge Isse on 1990 Mazda 929

It seems to be "overheating" and "burning fluid" out of the radiator. The overflow is fine but I have to add to the radiator and I do not see a leak ANYWHERE. The pressure is fine, and the cap was just changed and the thermostate is one year old and the water pump is two years old. I even changed the fan clutch. I cannot find a drop leaking anywhere.

Asked by for the 1990 Mazda 929