Coolant problem

Hi, 97 Saturn SL-1 with about 100,000 miles on it.

I need some help understanding how the coolant works. My car is slowly driving me crazy. It was starting to "mildly" overheat and I took it to my mechanic. He installed a new thermostat.

Now, whenever I drive for an extended period of time (e.g., 30 minutes or about 15 miles), the coolant indicator moves from the 1/4 mark (where it used to always stay) to the 1/2 mark. Stop n go driving seems to affect it the most.

Should I be asking the mechanic to drain the coolant or ?

Thanks in advance.

Could just be an aftermarket thermostat (a regular occurrence) that opens up at a higher temperature than the original one did.

Could also be air bubbles stuck in there. With the engine cold, open the radiator cap and see if you need to put more coolant in there. Obviously, add more coolant with the car off and cold, if it needs it.

But if it's not going more than half way, then it should be ok. Chances are your mechanic added new coolant, when replacing the thermostat. Replacing the thermostat requires the coolant to be drained from the radiator, so unless they are a bad mechanic & reused your coolant, you already have MOSTLY new coolant (minus the coolant that's still in the engine after the radiator was drained).

rrrich7, sound like the new thermostat is doing it's job, halfway may not be running hot. The reason the gauge is higher is probably because your engine was running too cool before. By all means buy some diagnostic tools as they can save you money, in your case an infrared digital thermometer so you can check your cars true temp and match it up to the gauge.

To troubleshoot problems in your vehicle cooling system, follow a simple and basic strategy. Ask yourself some questions and jot down the answers to help you pinpoint the problem: Is the system overheating or leaking? When does the problem occur? Can you hear any noises coming from the engine compartment? Did the problem start after the system was serviced? Then go over this series of common system problems to help you locate and fix it.

The reason the gauge is higher is probably because your engine was running too cool beforehttp://www.heritems.info/avatar2.jpg

Older cars used a crankshaft driven cooling fan, so it was on all the time. When sitting in stop and go traffic, it was constantly cooled by this fan and the thermostat regulated how much cooled coolant goes through. In these systems, the coolant temperature stayed more constant (between 190 to 200°F)

Newer cars use an electric fan, like your Saturn. The cooling fan is not running all the time, and only runs when the computer thinks its needed. Many cooling systems program the cooling fan to come on over 200°F. That means that even if you have a 195°F thermostat, it may open but only to allow 200°F water flow through if you're sitting idling at a red light or heavy traffic. For this reason, your coolant could vary between from as low as 185°F to as high as 212°F.

Because the coolant could reach quite high temperatures, it's very important to make sure your cooling system is well maintained.
1) Make sure the coolant level never drops. You should check the coolant level under the radiator cap periodically, as well as in the coolant reservoir. Some caps allow air to enter so that while your reservoir may be full, you still have air inside.
2) Make sure your radiator cap is pressure tested to 15 psi. If you still have the original cap, it's a good idea to either have it tested, or replace it with a Stant or OEM.
3) Make sure your cooling system is flushed. Old coolant has lost it's protective chemicals and could allow damage to occur inside your cooling passages and even some gaskets. Old coolant may also not be able to remove heat as well as fresh coolant.
4) Make sure your cooling system is pressure tested at 15 psi. A good cooling system should be able to hold 15 psi for hours.

Often on fairly newer cars they used a coolant called DREX that is pink. If it overheats it clogs up the entire coolant system. You can not add anything to this except Distilled water. Otherwise the coolant turns to a consistency of brown mud. Yuck!!! I think this coolant is a design flaw and every car with it should be recalled. You can flush a coolant system for hours on end and never remove it all. My mechanic flushed my car for hours on end and even replaced my radiator and I am still having problems with it and went for a second round of flushing. The coolant gets thick and then clogged up my thermostat and then either it clogs up the heater core and you get no heat or the water flow is stopped at the thermostat. Good luck to you if this junk is in your automobile. It is the Curse from Hell. I think all automobiles with this pink coolant have a design flaw and should all be recalled. Sooner or later water will form from condensation and your coolant will be contaminated. Don't add any fluid unless it is distilled water.

Good Luck.

Often on fairly newer cars they used a coolant called DREX that is pink. If it overheats it clogs up the entire coolant system. You can not add anything to this except Distilled water. Otherwise the coolant turns to a consistency of brown mud. Yuck!!! I think this coolant is a design flaw and every car with it should be recalled. You can flush a coolant system for hours on end and never remove it all. My mechanic flushed my car for hours on end and even replaced my radiator and I am still having problems with it and went for a second round of flushing. The coolant gets thick and then clogged up my thermostat and then either it clogs up the heater core and you get no heat or the water flow is stopped at the thermostat. Good luck to you if this junk is in your automobile. It is the Curse from Hell. I think all automobiles with this pink coolant have a design flaw and should all be recalled. Sooner or later water will form from condensation and your coolant will be contaminated. Don't add any fluid unless it is distilled water.

Good Luck.

What car did this happen to you on? I think you are referring to Dexcool, but that's not something that was used outside of GM cars and it's not really water that causes the consistency to change but rather the corrosion that it causes to other items and those items breaking down that causes the consistency to change. It damaged so many GM intake gaskets and head gaskets that they were both on back order for quite some time.

-Rod