I have a 2001 Mercury Grand Marquis four door sedan. The last couple days steam has been rising out of my dashboard. And it has an order of radiator water. Then this morning I parked, kept the car running and removed the radiator cap. The water/coolant didn't explode out as if the engine was overheated. Instead the water/coolant looked mushy and it bubbled out, almost emptying the water/coolant container. I poured water into the water/coolant container and put the radiator cap back on. A few minutes later i removed the radiator cap and it bubbled out again. I refilled it and turned the engine off. That is where I am.

SOURCE: 1986 mercury grand marquis LS overheating

Sounds like the thermostat is stuck closed.
If the car is overheating, they will also hurt perfomance.

But after sitting 8 yrs, it's hard to say what else might be wrong.
Was it just sitting, and you threw some gas in it to get it running? Or did you go through the car first to do some maintenance? Like an oil change, flush the gast tank and carb and put in all fresh. Change the fuel filter? and the list goes on. A car sitting that long can develope some problems just from sitting. If you could list what you have and haven't done to the car before this would help.

SOURCE: Car will turn over good, but not start. car is getting fuel.

In the trunk there is an emergency fuel pump cutoff switch. Make sure it's turned off before you take it anywhere and spend money.

SOURCE: my 96 meunder the mercury grand marquis is running hot

A cracked Intake manifold. Check the manifold in two places, on the front cross over behind the alternator and the base of the heater hose connector on the rear of the passenger side.

SOURCE: coolant leak from upper radiator hose where it meets engine

thermistate housing is the place you refer to it fuction is to hold a thermastate to open and close water flow at 150 to 190 degree according to car spectif the thermaste sticks it causes overheating and can blow the thermastate gasget, the tole cost is about 30$ at most for the thermastate and gasget...now many other things can cause a car to over heat and cause a hose leak and somtimes it is simple to just tighten the hiose clamp at the thrmastate and problem sovled see a water leak causes the radiator to lose presure and thus with out a sealed tight water cooling system the boiling point of water is lower and thus the car over heats when in doubt stop by the local gas station and have a tech take a quick look as it could be simple as the hose clamp difficult as a therm,astate but do not let it go to warp a head gasket as this blown headgasket is what is the end results of running a car to hot

SOURCE: steam coming from engine

water always can be used but wont last very long. fulling it up with water could work for about 10 mins at most. but as soon as possible full it up with coolant to last much longer. since its boiling point is much higher.