What does it mean when you keep smelling the coolant but see no leak?

Most modern radiators serve two purposes: to cool the engine, and to cool automatic Transmission Fluid. Coolant can get anywhere it touches, and a few places it doesn't. Coolant can get into the engine's combustion chambers. You'll note white exhaust smoke if that's the case. Coolant can get into the crankcase. You'll note your engine oil has a milky appearance if this is the case. Coolant can get into the automatic transmission. You'll note your ATF has a milky pink color if that's the case. In short, it doesn't mean anything definite. It could be any of the three things listed above, as long as you're SURE it's not leaking. Watch for leaks not only on the ground, but in the engine compartment, too. Also, keep the radiator level full ... see if you can tell how much coolant is being lost. If you have coolant in your engine oil or ATF, GET THIS FIXED NOW ... your engine is at risk. You want this coolant loss to be a leak, trust me.