My 2000 Cadillac Deville northstar motor is overheating and loosing coolant. I've changed thermostat twice?

The 1st time I changed the thermostat and added coolant, it didn't overheat for approx. 2 weeks. Then I had to put another thermostat in(thought this one didnt work) and put the cooldex antifreeze in as manual requested %26amp; it didn't overheat for another 2 weeks. Now nothing is working and I can't drive it from frequent overheating, Can someone help me and let me know what could be wrong with my car??
My 2000 Cadillac Deville northstar motor is overheating and loosing coolant. I've changed thermostat twice?
Best thing to do is to have the coolant system pressure tested,as well as the cap.The majority of the time it can be found that way.After the pressure test,If a leak is not detected Then you need to do what they call a block test.A block test kit you can buy at a aftermarket auto parts store.A block test is where you have the cap off of the radiator and put a tube in it to measure to see if any exhaust fumes are coming through your coolant passages. (blown head gasket ETC)
My 2000 Cadillac Deville northstar motor is overheating and loosing coolant. I've changed thermostat twice?
Radiator caps are a couple of bucks. You can try that. Rare, but caps lose their sealing ability.



If you added windshield washer fluid to the cooling system, that causes suds and overflow.



More than likely a blocked radiator core. Ask a radiator shop the charge if you pull the radiator or the charge if they pull it for a pressure check.



If you smell antifreeze in the passenger compartment through the defrost, that points to head gasket. Have the cylinders compression checked. Blown head also pumps oil out your exhaust. Your tailpipe will be black instead of gray.



On a different car, the last option is what I paid for after the mechanic misdiagnosed the first three repairs and charged me anyway.
Changing the thermostat doesn't really do much, they rarely go bad. If you still think it is the thermostat, remove the thing, you can run an engine without one. But I don't think it's your problem. Did you have a lot of miles on the vehicle? It could be a head gasket as someone else mentioned. It could also be they the radiator. After a lot of miles they don't work as efficiently as when new. You have all the same conditions that I had in my Mustang years back. I replaced the head gasket, radiator cap, and took out the thermostat and it still overheated. They problem turned out to be the radiator. gl
water pump radiator or blown head gasket id look for white lines on the radiator that would show leaks as the steam dries it stains the radiator or hoses or near the water pump if it blows white steam from exhaust you have bad head gasket

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