Originally Posted by nowthenkia
Thank you for your suggestions
How can air be admitted into the water system when the water system is under pressure?
You are losing coolant under pressure - air is being sucked back in to equalize the system / the displaced coolant,
Suggest you re-check the thermostat first, pull the thermostat, heat some water to > the opening temp., and place the thermostat in the hot water to make sure it is opening fully and evenly.
Gloves are recommended, kitchen tongs are handy to remove the thermostat and check it..
When cool, reinstall, making sure the metal (spring) portion of the thermostat is in the direction of the heat source (motor).. The thermostat s/b marked w/ direction of coolant flow, the spring portion that opens the thermostat should be pointing towards the motor.
You have (2) radiator caps (old and new), compare the Open PSI and make sure it matches what the system is rated for..
** Re-check the radiator, get a flow test done like Dr. Bob suggested,
** Purchase an InfraRed (IR) thermometer so you can more accurately determine:
The temp. at the thermostat outlet (where the top radiator hose connects to the motor),
The temp at the top radiator hose inlet,
The temp at the bottom radiator hose outlet.
You stated above the heater core was disconnected, where the (2) hoses going to the heater core (plugged) or properly (bypassed) ?
** If plugged and NOT bypassed, you may have omitted coolant from the engine, install a proper bypass using some hose connectors and a length of heater hose ASAP..
After you have verified the thermostat / that the system / hoses are hooked up or bypassed properly, place a piece of carboard under the vehicle, and run the vehicle until hot, this may take up to 1 hour or more.. Use the IR thermometer to closely monitor the temp at the thermostat outlet, DO NOT RELY ON THE TEMP GAUGE ON THE DASHBOARD.. Shut off, let cool some, and check the carboard for any coolant -> start tracing to find the leak.
Does your vehicle have an electric fan? Is it working properly?
If equipped w/ a diagnostic port, consider purchasing a scanner so you can see the real-time value of the engine coolant temp. sensor and compare the value against the IR thermometer reading at the thermostat housing..
Make sure you are purging all air out of the system when refilling coolant, this involves running the motor with the radiator cap off until hot / thermostat open, and topping off the coolant level in the radiator.. Shut the vehicle off, Make sure the overflow/expansion tank is filled to the MIN level, and squeeze the top radiator hose (wearing gloves/hand protection) to "burp" the system / force any trapped air into the radiator.. Top off w/ coolant as needed.
If the vehicle is overheating after (x) miles of driving, warm up the vehicle, drive 1/2 that distance, park, let the motor / cooling system cool down, and check the expansion tank level / and the radiator level.. Top off and try again.. (See above, trapped air in system),
If there is an air purge valve at the thermostat housiing, open it slowly to release any trapped air, close, and top off the radiator and expansion tank to the MIN level w/ coolant,
If no joy above..
*If the flow test on the radiator is good, consider the water pump suspect..
*If you do not have a service manual, consider getting one: I wouldn't be working on my vehicle without one.