98 saturn sc1
karpaul
09-20-2007, 08:17 PM
car has new thermastat,1.9 litre auto,temp gauge stays at 1/4 cool,as you drive and come to a stop,it boils over out of the coolant fill bottle,do not know if fans come on while you drive or when you get and leave and a sensor makes them come on
denisond3
09-22-2007, 11:09 AM
I can think of a few things that might cause the symptoms you have. First though: The fans should start whenever the engine is running and the coolant temperature sensor tells the PCM (the brain) that things are too warm. Also, if your car has a.c. (and its still working), the fan would likely run whenever it is on. And when the defroster is on. Anyway, starting with the easiest....
1. If your coolant recovery cap were loose or gone bad - the system would be likely to boil whenever you came to a stop. This is because the hot water in the head would boil at normal air pressure. While you are driving it is moving through the head, and be less likely to boil. The cap can be tested, or replaced. It would be a good idea to do a pressure check of the cooling system too.
2. A coolant mixture that wasnt right. It should be about 50% antifreeze, and 50% water. It will overheat if its just water - and maybe overheat if its just pure antifreeze. (Antifreeze has a high boiling point, but doesnt conduct heat as well as water.)
3. There are hoses that let the coolant flow through the heater until the car is warmed up, when the thermostat directs the flow through the radiator. Flow through the heater 'loop' is therefore necessary until the engine is fully warm. Otherwise you would have some hot spots in the engine block and head.
4. The gauge on the dashboard might not be correct. I think all Saturns use 2 coolant sensors. One for the PCM to monitor the engine temperature, the other for the gauge on the dashboard. They seem to be a common item to deteriorate. If the sensor for the gauge were wrong, you might still have overheating in the motor. If the sensor for the PCM is wrong, it may not turn the cooling fan on when it should. The sensors arent expensive, I got one of each for under $16. They look much alike but are different parts. The connectors are slightly different. On our 92 SL2 both of them are located on the side of the engine head that is right over the bellhousing of the transmission. They may be hard to see until the air inlet duct and wires and hoses have been moved.
5. Worst problem: A head gasket starting to leak. While driving alaong the leak would let steam be blown into the cooling system, which will displace water at the coolant recovery tank. A compression check might show this up as low compression in one or two cylinders. Did you replace the thermostat because the system overheated substantially? The overheating can result in the head being warped, and a head gasket failure can happen the next day - or not show up until months later; by losing water from the cooling system for instance. Sometimes (not always) water will show up in the oil due to a head gasket failing. It would look like chocolate pudding mixed with the oil - easy to see on the dipstick. Sometimes (not always) oil will show up in the coolant due to a failing head gasket - as lots of scummy gray muck in the coolant recovery bottle.
If air is getting into the cooling system from a bad head gasket, the steam/air bubbles would show up as bubbles in the coolant overflow bottle - even if the water werent boiling. When its fully warm, the water temperature in the engine head is 200f anyway.
6. The radiator could have lost its cooling efficiency, and be partly blocked. This is not common on a car only 9 years old, but could be the result of a head gasket that is failing. Gummy oily crud gets into the cooling fluid and finishes up on the cooler surfaces - in the radiator. If the a.c. condenser is dirty, filled with bugs and leaf bits - that can cut down on air flow into the radiator. On a Saturn the spoilers and air deflectors that are under the car are more important than on older cars - to help keep good airflow through the radiator in hot weather.
Im not saying your problem has to be one of the above - they are just the ones I can think of this moment.
1. If your coolant recovery cap were loose or gone bad - the system would be likely to boil whenever you came to a stop. This is because the hot water in the head would boil at normal air pressure. While you are driving it is moving through the head, and be less likely to boil. The cap can be tested, or replaced. It would be a good idea to do a pressure check of the cooling system too.
2. A coolant mixture that wasnt right. It should be about 50% antifreeze, and 50% water. It will overheat if its just water - and maybe overheat if its just pure antifreeze. (Antifreeze has a high boiling point, but doesnt conduct heat as well as water.)
3. There are hoses that let the coolant flow through the heater until the car is warmed up, when the thermostat directs the flow through the radiator. Flow through the heater 'loop' is therefore necessary until the engine is fully warm. Otherwise you would have some hot spots in the engine block and head.
4. The gauge on the dashboard might not be correct. I think all Saturns use 2 coolant sensors. One for the PCM to monitor the engine temperature, the other for the gauge on the dashboard. They seem to be a common item to deteriorate. If the sensor for the gauge were wrong, you might still have overheating in the motor. If the sensor for the PCM is wrong, it may not turn the cooling fan on when it should. The sensors arent expensive, I got one of each for under $16. They look much alike but are different parts. The connectors are slightly different. On our 92 SL2 both of them are located on the side of the engine head that is right over the bellhousing of the transmission. They may be hard to see until the air inlet duct and wires and hoses have been moved.
5. Worst problem: A head gasket starting to leak. While driving alaong the leak would let steam be blown into the cooling system, which will displace water at the coolant recovery tank. A compression check might show this up as low compression in one or two cylinders. Did you replace the thermostat because the system overheated substantially? The overheating can result in the head being warped, and a head gasket failure can happen the next day - or not show up until months later; by losing water from the cooling system for instance. Sometimes (not always) water will show up in the oil due to a head gasket failing. It would look like chocolate pudding mixed with the oil - easy to see on the dipstick. Sometimes (not always) oil will show up in the coolant due to a failing head gasket - as lots of scummy gray muck in the coolant recovery bottle.
If air is getting into the cooling system from a bad head gasket, the steam/air bubbles would show up as bubbles in the coolant overflow bottle - even if the water werent boiling. When its fully warm, the water temperature in the engine head is 200f anyway.
6. The radiator could have lost its cooling efficiency, and be partly blocked. This is not common on a car only 9 years old, but could be the result of a head gasket that is failing. Gummy oily crud gets into the cooling fluid and finishes up on the cooler surfaces - in the radiator. If the a.c. condenser is dirty, filled with bugs and leaf bits - that can cut down on air flow into the radiator. On a Saturn the spoilers and air deflectors that are under the car are more important than on older cars - to help keep good airflow through the radiator in hot weather.
Im not saying your problem has to be one of the above - they are just the ones I can think of this moment.
sierrap615
09-28-2007, 01:21 AM
most likey its a bad cap. meaning the coolant will boil at the reliativily low temp of 212F. the fan is set to kick in at 220F so without a properly working cap, its very unlikely to turn on.
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