I have a 2003 Ford taurus. I keep on losing a lot of the coolant out of the resevoir cap. It percolates, then I lose it. I've replaced the cap twice. The first time it looked like the cap was broken, ok problem fixed. Then I get a second cap, and it happens again last night, now the cap won't screw properly and looks possibly damaged. My car doesn't overheat. Do I need to spend more money on a better cap?

3 ways of loosing the coolant/water search for leak -hole in radiator,hoses at connections or damaged,water pump,heater core and hoses //blown head gasket coolant being burnt will show white smoke out tail pipe ,oil will show milky cocoa color ---//transmission oil cooler lines have internal damage in radiator and transmission has fluid draining

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.

run fault codes and find out which sensors are faulty. The loss of power indicates that it is in limp home mode . Check oil level and coolant level at the radiator cap.

try to run the engine while the cup is removed, and check if there are any bubbles formed, it could be that the cylinder head gasket is burnt

Check with the auto parts store to see what the fuel sensor looks like, It should be accessible and I have seen those go on the smaller chevys like aveo.
Look up on internet replacing gas recirculation sensor on google

you should have the cooling system pressure tested and inspected for a leak that may only show up under pressure.it could be a slow leak from the water pump,frost plug,head gasket which wouldn`t show up in the oil,heater core.it sounds like a small leak but this is the best way to start to find it.

Sounds to me like a blown head gasket. Even if your vehicle is not warmed up, if your reserve tank is boiling fluid out of it when the engine is cool, it's most likely losing compression from it all going to your reserve tank. And thats why it's fluids coming out of your reserve tank. BUT, if your radiator is clogged then the same thing could happen. So i would start out cheap before you have to replace a HG. Thanks, James Booth been a mechanic for 6 years

I have a 1993 Taurus GL V6 3.0L..I"am experiencing a loss of power. Hesitates on acceleration Only when It's cold.When is get hot it runs very good. I have Replace Spark Plugs Cap & rotor were change air filter & fuel filter & TPS/EGR..... & it has a rebuilt ENG in it...this could be a sensor. But which one could it Be?

What Can This Be?

its vapor locking try leaving the fuel cap alittle lose
if that works then replace the cap or just leave it a little lose

You will overheat the engine if losing coolant.Firstly replace the cap with a new one,Is the engine temperature normal when you stop ? If its over temperature it will still blow out coolant. Check the radiator for blockage of the tubes & ensure the fan belts and water pump are in good order. Worst case is a blown head gasket can test for combustion gases in the coolant