Q: Overheating car no leaks

The cooling system, including the radiator pressure cap, should be pressure tested to determine if there is a leak. Leaks can be outwardly visible (external) as well as hidden (internal) in a circumstance for example where the cylinder head gasket(s) or intake manifold gasket (in some applications) is leaking. In addition to a leak, your car should also be evaluated for overheating. It is possible, for example, to have a stuck closed thermostat that causes the engine to overheat and a consequence is pressure rises in the cooling system, the radiator pressure cap opens while driving, and so much coolant is expelled into the overflow reservoir that it flows through the overflow tube onto the ground when you are driving. Eventually, the coolant gets low enough that it doesn’t leak out further in this fashion and so you think there’s no leak when you stop and park the car. In this scenario (stuck thermostat), maybe there isn’t a leak but the car is overheating and that will damage the engine. The best thing to do is request an overheating diagnostic and the responding certified mechanic will check for leaks as well as investigate the overheating possibility.