It might be a bad thermostat, or something worse, such as a blown head gasket/cracked head. Either of those scenarios will cause the cooling system to pressurized beyond it's specified capacity, and the pressure will force the coolant out of the reservoir.
Could be a hose leak, a radiator leak or a head gakket leak. The water in the reservoir will get "sucked" into the cooling system if the level get low. Look for water on the ground or signs of spray under the hood. If it's a head gasket, look for water dripping from the exhaust pipe on start-up and/or steam. That would indicate that water is getting into the combustion chamber.
It probably has a leak. Here's something to check - the radiator has a tube coming out to the reservoir, so when it gets hot and expands the coolant goes into the reservoir and should go back into the radiator when it cools, but if your reservoir has a crack and the coolant leaks out, well it's gone and can't go back into the radiator - this would cause a lot of loss of coolant.
If you have excessive bubbles coming from your radiator (remove the radiator cap only when the engine is cold) with the engine running, Then you have a blown head gasket. You may need to increase the idle speed a bit to see the exhaust gasses coming out. Fill the radiator to over full with water. An other cause is: the engine must be able to pull a vacuum on the reservoir hose to return the water to the engine as it cools. I have found that the plastic reservoir cap may have a hole or crack under the cap. Take the cap off with the hoses attached, clean it, then blow on the hose covering the other hose end to see if it leaks. It must not leak. If it does then water can fill the reservoir but not return to the engine.
You should try to avoid using a stop-leak product. All you'll do is gunk up your cooling system reducing cooling capacity and you'll never get that stuff out. If you have a radiator leak, remove it (usually just a matter of an electrical connector for fan(s) a couple of hose clamps and a couple of bolts holding the radiator in a bracket) and take it to a radiator repair shop. A little solder in the right place and you have a like-new radiator with full cooling capacity. If you've already added stop leak to the reservoir, remove the reservoir and rinse the stuff out. Coolant is drawn out of the reservoir when the engine is cooling down. Best case the hose from the reservoir to the radiator will get plugged. Worst case you could get a lump of sealant that might sit for hours congealing (remember the coolant isn't circulating) before the engine is started again. Cheers
It may appear to be coming from the radiator. A leak is a leak, and it can cause serious prolems inside your engine. It could be a house, a gasket, the water pump, or you may have missed a radiator leak. Over heating can cause this too, and that presents other problems. Lastly, your radiator cap may be failing. That's a cheap first step. Don't let this go for long, keep fluid in your system at all times.
How many 3s in 313433535333?
Is it true that one human year is equal to seven dog years?
How many fifths are in 6 tenths?
What is half of 74?
Who has won World Series both as a player and manager for the New York Yankees?
How do you spell water with 3 letters?
The more you take the more you leave behind what am I?
What Roman Numeral is xxx1x?
What is doomscrolling?
How did the Wiffle Ball get its name?
Do schools still teach cursive writing?
Can eggs break inside a chicken?
Why do books come out in hardback first?
What happens when a beehive gets too full?
What is the difference between an optometrist and an ophthalmologist?
How can you tell when someone's lying?
What are the advantages of stress interview?
Why the story entitled origin of fair complexion and fair hair?
Ano ang kahulugan ng iskolarling pagpapahayag?
What is a classified data spill or negligent discharge of classified information?
Ano ang papel na ginagampanan ng mga impormasyong ito sa mapa o sa globo?
Which of the following statements is true about storing classified documents?
When two pieces of cui or other unclassified information are posted online together?
What are the solutions to the crazy kiwi game?