HEATER REPAIR I RECENTLY REPLACE BOTH MY RADIATOR AND THERMOSTAT TRYING TO RESOLVE THE HEATING PROBLEM WITH MY CADILLAC. TO MY SURPRISE THE HEAT STILL DOES NOT WORK PROPERLY. I DONT THINK IT IS THE HEATING CORE BECAUSE FROM MY PERSONAL EXPEIRENCE THAT NORMALLY MAKES A MESS ON THE FLOOR BOARD. MY TEMPERATURE RISES REALLY FAST ALSO. I CAN BE DRIVING AT 20 TO 30 MPH AND IT RUNS UP TO 240 OR 250'S REALLY QUICK. PRIOR TO MY HEATING PROBLEM I NEVER SEEN IT THAT HIGH. I REALLY NEED TO TAKE CARE OF THIS ISSUE AS QUICK AS POSSIBLE. I AM IN ALASKA NOW AND THE WINTERS HERE TAKE NO PRISONERS. ANY KIND OF INFORMATION OR ASSISTANCE YOU CAN PROVIDE WILL BE GREATLY APPRECIATED. THANK YOU FOR YOU TIME

Incorrect timing can also cause overheating along with bad radiator, bad pump, fan not working, bad thermostat, AC, inadequate lubrication, low coolant level, engine load as when towing, etc.
Until issue resolved put your heater on full blast and lower the window.

if I understand your problem the car is overheating with the A/C turned off? u may have a bad thermostat or a blockage in radiator. open the radiator cap when car is cold and start the engine. look into the radiator and see if fluid is flowing if its not that's good it means when engine is cold the thermostat is closed. after the car reaches normal operating temp the stat should open and the fluid flow through the radiator. if this is not the case then replace thermostat. if it passes this test then check the top radiator hose to see if its hot then check the bottom hose it should be about the same temp as the top. if it is cold or just warm then u most likely have a blockage in the radiator. if so u can replace it or have it redone at radiator shop. if radiator is ok then look at heater core. when the engine is warm u should have heat. u can use the hose test here as well. the two smaller hoses that go into firewall to heater should be hot when using the heat if not then there is a blockage in heater core.. hope this helps

water passes through the heater core VIA radiator if water is not heating up you will only feel slight heating or no heat possible cause is a bad thermostat water free flowing through radiator and engine not getting a chance to heat up enough. have radiator pressure check or just replace thermostat there cheep usually $8.00 to $15.00 you do have a Mercedes like Cadillac and Continentals parts cost more.

good luck, hope this helps (PTL)

Feel the 2 tubes at the firewall for the heater core. If they are not getting hot, the heater core needs to be flushed out or replaced. I had this problem with a 1990 Cadilac Deville, it was just a plugged up heater core.

Remember to install sealant after flushing out the system to prevent leaks.

i didn't see you last posting about your water pump but theres is a tiny radiator called a heater core. it has the same hot water running through it as your big radiator and engine have.so when you turn your thermostat to hot and kick on the fan the fan blows through the heater core and wallaa you have heat you probably need a thermostat.if you have no heat and it is overheating hear and there that's probably what you need.make sure you see if you filled the radiator up all the way when you changed the water pump.

check the oil level

1st check all hoses to the radiator. a hose that you can squeeze easily with little effort may be bad. Replace the 2 large hoses and the 2 hoses to the heater core. It also could be the radiator is clogged. If you remove the radiator and take it to a radiator shop they can clean it out for you for a reasonable price. If it is a plastic radiator you may have to replace it with a new one.

There is a blockage in the engine coolant path causing insufficient cooling. When the coolant flows, it removes the heat produced from engine combustion to radiator to cool. If there is no flow then the coolant becomes stagnant, therefore the heat is built up without being dissipated to nowhere hence the engine gets overheated. If this is not fixed then the heat will cause the head-gasket blown due the the metal expansion.
Repair at this stage becomes very expensive.
1- Take off the thermostat.
2- Put back the hose connection.
2- Run the engine and feel the upper hose to see if cooling flowing through it.
4- IF Yes. Run engine like this for few days, if no over heat , buy a new thermostat and put it back. Your problem is resolved.
5 IF No. You have a bad radiator. It clogs up so you don't feel the cooling flowing. Buy a new radiator, don't ever use a rebuilt one.
Good luck.

Hello,
The thermostat was a good choice however you should go to a service station and get a complete cooling system flush.
your heater core and or radiator could be clogged.

You probably just need to backflush your heater core. You can use a hose to flush it back and then forward. You'll be surprised at how much sludge and gunk will come out.