Water warning light

what causes the water in my water resovoir to become hot

Are you actually expecting help from anyone here? Shockingly enough, people need to know what kind of car you have, how many miles are on it, under what conditions the problem occurs, whether you’ve done regular maintenance, and other details like that.

sorry new to your forum,it is a peugot 607 2.0 hdi,2003.It has done 65000 miles fully serviced,last serice at 63000 miles


Running the engine will cause it.
Heat is naturally produced by an internal combustion (fire inside!) engine. For the coolant to become hot is normal. When it becomes so hot that it boils out or overflows, that is not. Many things can cause overheating, a bad thermostat, low coolant, bad water pump, leaking hoses and gaskets, faulty cooling fan or radiator, belts, etc.

What is your coolant doing other than becoming hot?

Explain the warning light, please. Does it come on every time you drive or only when stopped and idling? You really don’t want to drive it if it is really overheating. That is what must be determined. Is it getting too hot or is the warning light giving false information?

If it is drivable, have your car’s codes scanned at Autozone or Advance for free and post the code(s) back here in number form like: PO123, etc.

Maybe somebody can give you a heads-up.

the engine warning light came on a few days ago I replenished the resovoir but the light still came on everytime I ran the engine it says radiator coolant level low. I checked the resovior but it was still full. The engine has never over heated. Today when I checked the resovior it was empty so I replend it and after I had ran the engine for 10 minutes 3 hours later when I checked the resovior it was still full but the water was warm.

If you are using WATER in the cooling system, rather than the required mix of water and antifreeze/coolant, that would cause the engine to run hotter than it is designed to do. And, since it is running hotter than normal, that water will boil away rapidly. If you continue to use just water in your cooling system, you will damage both the engine and the radiator.

The COOLANT is supposed to get hot. As the car runs, the COOLANT cycles through the entire cooling system, and uses the radiator to expel waste heat from the engine. Every underhood photo I can find suggests that this car uses a surge-tank system, and the cap to the tank is the pressure regulator. This means, the tank is not just a recovery tank, but an integral part of the cooling system. The coolant should be at temperature and pressure as the rest of the cooling system. You should let the car completely cool before removing the cap.

As stated by VDCdriver, I hope you are using manufacturer recommended coolant and not water. Straight water will cause the system to run hotter, and can lead to serious damage to the engine.

Has the car ever overheated? If not, the coolant loss is most likely from a leak. A hose leak is cheap and easy to fix. A radiator leak or surge tank leak is easy, but can be costly to fix. If it is inside the engine, it will neither be easy or cheap. Let your mechanic know, and he should know what to do.