Losing coolant and water noise in dash of 2005 equinox

1. The radiator cap if working correctly it will release pressure in the system provided the cap you have is the correct pressure setting. If you are having a problem with pressure then replace the cap with a new radiator cap with the correct pressure setting. Do not use a cap with a pressure setting other than the original equipment pressure spec. So you do not go to the parts store and buy any radiator cap on the shelf that fits because they come with different pressure ratings and some of these will be totally unsuitable for your car.

2. If the pressure valve is stuck in the "old" cap the pressure release system will not work.

3. Overheating
Air pockets in the cooling system can definitely cause overheating and can retard coolant flow through the system. If you are draining the radiator to replace the coolant or replacing the radiator you need to follow the correct procedures for bleeding air out of the system for that particular engine after coolant refilling. Some engines have bleeder screws on the cooling system to assist in the air bleeding procedure and some don't.

There are various causes for overheating so don't assume it will necessarily be solved by bleeding any remaining air from the cooling system and replacing the radiator cap with one that works.

Other causes can be...........
1. Faulty cooling system thermostat. (Replace the Thermostat)
2. Faulty water pump, especially if the impellers have corroded away or have disintegrated in the case of those design genius water pumps with plastic impellers. (Replace the water pump)

3. Cooling fans not working and if so the cause needs to be tracked. Check that your fans are kicking in. If the engine is overheating the fans should be running because they will switch on when the coolant reaches a specific temp and well before the coolant gets excessively hot.

4. A partial blockage in the coolant passages inside the engine but not in the radiator if you have a new one. If the coolant is not changed at the required intervals(frequently the case with many owners) or is over diluted with water you can get a build up of debris. If products like stop leak have been used in the system this can create similar problems with partial blockages inside the engine coolant passages.

5. A compression leak into the cooling system.
If you have bled air from the system and have continuous air bubbles in the cooling system I would suspect a compression leak. In that event a basic leak down test will show if you have compression gasses leaking into the cooling system and from which cylinder(s). The spark plug is removed and compressed air is forced into the cylinder via the spark plug fitting and air bubbles will show up in the coolant of there is a leak into the cooling system.
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Have the problem with overheating addressed immediately. Running the engine with an overheat condition will cause expensive engine damage many times the cost of fixing the overheating issue.

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Depends on where the coolant is going.
If it is an external leak it could be a leaking water pump. If there are no external leaks and you are loosing coolant, it could be a blown head gasket. Especially if the engine has already overheated once.
A sticking thermostat would cause the engine to overheat and then loose coolant from the overflow tank. But not until it overheats.

all cars do that when , the engine coolant is low
the heater core is full of AF coolant
if it makes noise , its got air there. (bad)
so with car dead cold.

take off the radiator cap, oops the coolant is low.
do the service on the car and this will not happen.
do not trust the side expansion tank, and for sure never let it run dry of this will happen.

If the t/stat fails in the closed position an overheat will result. I have had a brand new one fail a week after I put it it. Rare but does happen. Have you checked the rad hose, is it warm, hot, or cold during the overheat condition? Is the coolant actually flowing through the system? When its cold (after sitting overnight) remove the rad cap, look at the fluid level...normal? If so start the car and let it run with the cap off..feel the rad hose soon as it starts to get hot look in the rad (be careful if your system has a vapor lock it may spit the air out, best to have a face shield on just in case!)..is the coolant flowing? It should start flowing at some point. If not the t/stat is stuck closed or the water pump is broken/seized.

Add coolant. Find the leak and repair it. You won't have heat when the coolant is low.

it sounds like you have a major air pocket. there is a vacuum system that works rather well when filling up a cooling system

thermostat

You have a coolant leak somewhere on your motor. Your coolant is low and you are hearing the air pocket being pushed through the system.

A thrmostat that does not open and close would cause these very symptoms. Since it does not allow coolant to flow through the system, it will make the engine overheat. Since it won't allow the "heated" coolant to pass by your fan, the heat will continually blow cold air.

Stop driving the car immediately, becuase the next step will be some blown gaskets - especially head gasket. Other possible reasons can be as follows:-- It could be just low on coolant.
if it is then add coolant...
with low coolant the water pump can not move enough coolant to supply hot coolant to the heating system . also if its low the motor will over heat fast..... If the system is full then you may have other problems.. such as
1) bad thermostat
2) bad radiator cap ( not holding pressure so it will leak coolant)
3) blown head gasket .
4) bad heater core (leaking coolant out.. check the floor board under the dash on the passenger side.)
5) bad hose or clamp. Thanks. Keep updated for any more query. You can rate this solution and show your appreciation.

Check the water coolant level because some of the hot water goes into the heater radiator behind the dash. Seems you have air in the system.