not necessarily. my sister's 90 corolla had a leaking hose and radiator. they made no puddle on the ground. a dye was put in her radiator to find the leaks. small one at a clamp on 1 hose and the radiator was weeping. leaks were not large enough to puddle on the ground but she lost enough coolant to make her guage go up and have to have antifreeze replaced. she now has a new hose and radiator. she was also getting alot of air in her heater core so her heat was spotty from the leaks. that has now stopped. air in the cooling system will make it idle rough also.