caddy overheats when heater is on

a couple of time when i ran the heater, the warning light said engine coolant hot. It doesn't do it all the time. I have notice that when i look at the coolant overflow tank, sometime the coolant will have came out
from the top cap where you fill it up at. Can someone tell me what cause this please. I am scared to run my heat and december is near.
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If the coolant was replaced or very low since last winter the problem may be from air trapped somewhere within the cooling system.
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On November 21, 2005 MeanMeana2424 wrote:
a couple of time when i ran the heater, the warning light said engine coolant hot. It doesn't do it all the time. I have notice that when i look at the coolant overflow tank, sometime the coolant will have came out from the top cap where you fill it up at. Can someone tell me what cause this please. I am scared to run my heat and december is near.
_____________________________________________________________________________
Hello Meana:
Your problem could be complex or quite simple depending on the diagnosis. What year is your Cadillac? If it is 1995 or earlier you will be able to find out the problem through your onboard diagnostics system which will provide error codes to troubleshoot your problem. If you own a later model (1996 to present models) then you will need to have an ASE mechanic to diagnose your codes.
If coolant is escaping through your overflow tank cap, then that means that it is bad and needs to be replaced. The primary purpose of this cap is to maintain even pressure in the coolant system. Without complete, even pressure, then the system will fail at other points. If you have a Northstar (NS) engine, then it is in your best interest to resolve your problem at the soonest possible time. Once your NS overheats then a multitude of problems could, and all of them are expensive, including the possibility of blowing your engine (head gaskets) which might then be necessary to replace your engine.
On the other hand, a new cap might solve all of your problems, and it does not cost much to replace. Purchase one soon. I hope this helps.
Peace,
Famous
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On November 21, 2005 MeanMeana2424 wrote:
a couple of time when i ran the heater, the warning light said engine coolant hot. It doesn't do it all the time. I have notice that when i look at the coolant overflow tank, sometime the coolant will have came out from the top cap where you fill it up at. Can someone tell me what cause this please. I am scared to run my heat and december is near.
_____________________________________________________________________________
Hello Meana:
Your problem could be complex or quite simple depending on the diagnosis. What year is your Cadillac? If it is 1995 or earlier you will be able to find out the problem through your onboard diagnostics system which will provide error codes to troubleshoot your problem. If you own a later model (1996 to present models) then you will need to have an ASE mechanic to diagnose your codes.
If coolant is escaping through your overflow tank cap, then that means that it is bad and needs to be replaced. The primary purpose of this cap is to maintain even pressure in the coolant system. Without complete, even pressure, then the system will fail at other points. If you have a Northstar (NS) engine, then it is in your best interest to resolve your problem at the soonest possible time. Once your NS overheats then a multitude of problems could, and all of them are expensive, including the possibility of blowing your engine (head gaskets) which might then be necessary to replace your engine.
On the other hand, a new cap might solve all of your problems, and it does not cost much to replace. Purchase one soon. I hope this helps.
Peace,
Famous
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Hello Meana:
This is an additional note to my previous posts to your original message. I would also advise you to take your car in to have a "pressure test" conducted on your coolant/heating system to see if there may be other leaks. This is the best diagnostic test for leaks, and can positively determine your car's problem. The test is not very expensive. Your local shop should be able to handle this procedure. Once the test is completed, then your shop should be able to provide you with the cost of labor and parts for any further work. If you cannot afford the work to be performed at this time, then tell your shop that you need to wait a while. They will then only charge you for the diagnostic "pressure test."
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I still need help, my I have had my radiator checked, my water pump checked, thermostat replaced and a pressure and block test done on my car. It still sometimes pops up with the message Engine Coolant Hot, and when you pop the hood the coolant overflow tank looks like old faithful. the only things that have been replaced is the thermostat twice, first time it was a 195 degree, it had the warning pop up a day after, next thermostat was 180 degree, and it was fine for 9 days, now the warning message popped up again. the mechanics are stumped. what else is left that can cause this problem? Any leads please help me? I don't know what else in my car to have checked. If it helps i drive a 94 sedan deville, and the problem is intermitten, it doesn't happen all the time. Please help.
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Looks like you need a different "mechanic"!
Likely culprit is the electric radiator fan motor or the switch (temp. sensor) that turns it on.
When it is hot, is the fan running? If not, does the fan run when you turn on the A/C?
It is hard to assess the condition of a radiator while still on the car. It is still possible that the radiator is (partially) blocked.
Good luck!
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Hello Meana:
I tend to agree with Ken about the radiator fan. Here is some information about how to troubleshoot this possible problem. "If the engine is overheating and the cooling fan is not coming on when the the engine temperature rises to an excessive level, unplug the fan motor electrical connector and connect the motor directly to the battery with fused jumper wires. If the fan does not come on, replace the motor. If the radiator motor is okay, but it is not coming on when the engine gets hot, one of the fan relays might be defective. There are three fan relays. A relay is used to control a circuit by turning it on and off in response to a control signal by the Powertrain Control Module (PCM). These control circuits are fairly complex, and checking them should be left to a dealer service department, or a independent Cadillac repair shop. If you live in San Diego County area, then I can recommend a local shop for you. Sometimes, the cooling fan system can be fixed by simply identifying and replacing a bad fuse and/or relay.
All 1992-1994 models equipped with Electronic Climate Control can display trouble codes, which can be used to diagnose engine and body components. Check your owners manual about how to access the Body Control Module (BCM) codes, which include those that cover heating, cooling and air conditioning. A problem with the engine cooling fan circuit will display a code. A problem with the Engine Coolant Temperature (ECT) will dispaly a code during ECM diagnostics.
I hope this helps. If your shop has failed to conduct any of the above tests, then I would seek another Cadillac repair mechanic.
Peace,
Famous
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