Both. The reservoir is the overflow. But in the event your radiator is low, your reservoir will back it up.
The radiator capacity for a 1998 Toyota Camry is two gallons. This includes coolant stored in the engine block and radiator.
There may be other reasons for the vehicle to be overheating but yes if you have let the reservoir run dry then it wont have suction to draw fluid back into the radiator so you will have to fill the radiator as well.
It should be on the bottom of the radiator.
Most likely because you have added to much coolant when it was cold.
Should be either at the bottom of radiator or at the rear lower section of radiator
You need to check coolant temperature sensor and the water pump.
Where is the radiator drain plug in a 1995 Toyota Camry
my 1993 Toyota Camry radiator had a hole in it it was overheating. I replaced the radiator. The car is still overheating where is the thermostat located. First, drain your coolant from the radiator. Find your lower radiator hose and follow it to the metal housing. This is the thermostat housing. Remove the 2 nuts with a 10mm wrench. Remove the thermostat and replace with new one and new gasket. Re-install and re-fill your radiator with new coolant. Drive the car with heater running. Allow the engine to cool and top off the radiator. Add coolant to the reservoir to halfway between Full and Low.
On the left side of the engine compartment there is the reservoir for the power steering fluid. Make sure that you do not put steering fluid in the radiator reservoir.
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Check the coolant reservoir in the engine compartment. There are marks to assist you with proper level. If it's empty you need to add coolant ASAP.
It should be at the bottom of the radiator plus there is at least in the engine block.