Coolant leak from top - 2005 Mercury Grand Marquis

Strange but do you think a hose has a pin hole that is spraying coolant up?
check the inner hood for over spray.
Clean the engine then drive it & look for more obscure places that might be wet.

So the level keeps dropping in the reservoir? If you have to keep adding coolant to the reservoir, the system is leaking or losing coolant somewhere. Have the system pressure tested to find the leak. Is the reservoir itself leaking? When the level gets low enough, first the reservoir will go dry, then the radiator level will start to drop.
Here's how the reservoir works: coolant is under pressure from the radiator cap seal. As coolant heats up from hot engine, it expands, and pressure forces the radiator cap seal up, coolant is forced into the reservoir-remember the hot mark on the reservoir? When car is shut off, coolant contracts, creating a vacuum in top of radiator. This vacuum works to suction coolant back from reservoir into the radiator, keeping the radiator topped up, and coolant should now be at the lower cold mark on the reservoir. It is a closed, sealed system. The only loss of coolant will be a very small amount of evaporation from the reservoir. If coolant level keeps dropping, there is a leak somewhere.

IF YOU GOT TOO MUCH WATER IN COOLANT SYSTEM AND DONT HAVE 50 / 50 MIXTURE OF ANTIFREEZE AND WATER. WATER WILL EVAPORATE BOIL AWAY.CHECK FOR COOLANT LEAKS LOOK AT TOP AND BOTTOM RADIATOR HOSES LEAKS, CHECK FOR COOLANT LEAKS AROUND BOTH RADIATOR CONTAINER AND RADIATOR CORES LEAKING. CHECK WATER PUMP WEEP HOLE. IF LEAKING WATER NEED REPLACING, CHECK ENGINE CRANKCASE ANTIFREEZE WILL LEAK IN CRANK CASE OR LEAK IN THE INTAKE GASKET COOLANT WILL BURN WITH FUEL.MANY THINGS WILL CAUSE COOLANT LOST.

CAR OVERHEATING FIRST CHECK FOR LOW COOLANT IN THE RADIATOR COOLANT OVERFLOW JUG.IF COOLANT LEVEL IN OVERFLOW JUG LOW REFILL ADD COOLANT BACK TO THE FULL COLD MARK.PUT RADAITOR CAP ON COOLANT OVERFLOW JUG START ENGINE LET IT IDLE UNTIL IT OPERATING TEMPERATURE.MAKE SURE TOP RADIATOR HOSE GETTING HOT WHILE ENGINE WARM UP.IF TOP RADIATOR HOSE DONT GET HOT WHILE ENGINE IDLING YOUR THERMOSTAT COULD BE STUCK CLOSE CAUSING CAR TO OVERHEAT.IF TOP HOSE IS GETTING HOT.CHECK FOR COOLANT LEAKS CHECK TOP RADIATOR HOSE AND BOTTOM RADIATOR HOSE FOR LEAKS.CHECK FOR LEAKS AT THE RADIATOR CORES AND PLASTIC SIDE CONTAINERS.IF ALL IS GOOD ENGINE OVERHEATING WHILE IN A LONG TRAFFIC LINE, COOLANT FANS NOT COMING ON.COULD HAVE FAULTY ENGINE COOLANT TEMPERATURE SENSOR OR BLOWN COOLING FAN FUSE OR RELAY.COULD HAVE PCM FAULT.MAKE COOLING FAN ELECTRICAL CONNECTORS AND WIRING NOT DAMAGE OR BROKEN.

TO FIX COOLANT LEAK.YOU HAVE TO LOCATE IT.BEST TIME FIND COOLANT LEAK WAIT UNTIL MORNING.ADD COOLANT UNTIL COOLANT LEVEL IN RADIATOR CORRECT. START THE ENGINE LET IDLE UNTIL START GETTING HOT.THEN TURN OFF ENGINE.COOLANT PRESSURE WILL PUSH COOLANT OUT WHERE LEAKS ARE.CHECK TOP RADIATOR HOSE AND BOTTOM RADIATOR HOSE.CHECK AROUND RADIATOR LOOK DOWN BELOW COOLANT FAN AREA BEHIND RADIATOR.LOOK FOR LEAKS AT RADIATOR CORES AND SIDE CONTAINERS.CHECK FOR COOLANT LEAKS AROUND WATER PUMP GASKET OR WEEP HOLE.CHECK FOR COOLANT LEAKS AROUND HEATER HOSES AND HEATER CORE.CHECK ENGINE CRANKCASE FOR COOLANT LEAKS.

ENGINE NOT GOING TO START IF GET TOO HOT FIRST THING I WOULD REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP THEN ADD COOLANT UNTIL COOLANT LEVEL CORRECT THATS WHEN THERMOSTAT OPEN UP AND TOP HOSE HOT.CHECK FOR LEAKING RADIATOR HOSES CHECK TOP RADIATOR HOSE CHECK BOTTOM RADIATOR HOSE.CHECK FOR LEAKS AROUND THE RADIATOR LOOK DOWN BELOW COOLANTS FANS CHECK FOR LEAKS AT RADIATOR CORES OR LEAKS AT THE RADIATOR PLASTIC SIDE CONTAINERS. CHECK FOR LEAKS AT WATER PUMP WEEP HOLE AND CHECK FOR LEAKS AT THE HEATER HOSES AROUND ENGINE BLOCK TO THE HEATER CORE HOSES. THERE IS A REASON CAR OVERHEAT.IF CAR OVERHEAT WHILE DRIVING YOU HAVE FAULTY THERMOSTAT OR LEAKING OUT COOLANT OR BLOWN HEAD GASKET.IF ENGINE OVER HEAT WHILE SITTING DURING A LONG IDLING PERIOD.YOU COULD HAVE FAULTY COOLANT TEMPERATURE SENSOR OR FAULTY COOLING FAN FUSE OR RELAY.HOT WIRE COOLANT TO SEE IF IT RUNS IF NO REPLACE FAN MOTOR. IF YES FAN MOTOR COULD HAVE FAULTY WIRE OR PCM FAILURE. CHECK ENGINE CRANKCASE IF OIL LOOKS LIKE MILK SHAKE ENGINE HEAD GASKET LEAKING.

Most of the time when I see coolant leaking at the rear/top of the 3400 engine, beneath the throttle plate area, it's usually coming from the intake gaskets. There is a coolant cross-over passage at the rear of both heads and as time passes the gasket will sometimes split along the sides of this passage and coolant will begin to leak out. It can be tough to see clearly whats going on in this area well enough to pinpoint the exact source of the leak so it may take a bit of time to find it. Often with an intake gasket leak the coolant will puddle on top of the block then drip down the rear side of the engine and drip off of the pan or transmission bell housing. Hope this helps you find your problem!

There is a metal coolant crossover tube with 5 gaskets 2 hoses and a thermostat above the transaxle anyone or all of these could be leaking

Use liquid soap on top of the coolant line, starting from the coolant tank hose, so to determine where the leak is coming from.

My coolant leaked out and on top there is a large hard plastic container, I had to replace it, that stopped my coolant leak.