Coolant light on

[taxidermist]

I have a 2000 intrigue w/ 125000 mi the coolant light comes on and stays for a little bit then goes off? the coolant is full and also the temp needle goes from middle to high then back to middle then up again?




Thanks for any help
Rob

[Ruley73]

Sounds like either a bad thermostat or a faulty coolant temp sensor. I'm not sure how hard either of these are to replace. The thermostat is located on the serpentine belt side of the engine where the radiator hose goes on the 3.5L. You may need to go to the dealer to get the thermostat. I'm not sure where the coolant temp sensor is located on the engine. On most GM cars they are located somewhere on the intake mainfold. Any autoparts decent autoparts store should have this sensor in stock for under $30.

[JTrujillo86]

The coolant level sensor on most GM cars is on the underside of the surge tank. You can purchse this for, like Ruley73 said, about $30.00. You need to drain the coolant and remove the surge tank. Turn the tank over and unclip the sensor. Then unplug the black cord from the sensor. The other sensor should just slip right in. Before you put the surge tank back into the car, plug the black cord into the new sensor.

Jeremy

[JTrujillo86]

BTW, there is only one bolt that you need to unscrew at the bottom of the surge tank. After unbolting the tank, I think that there is a little lip on the tank that slids into the fender that you just need to manuver out.

Jeremy

[paulkramer]

You guys are talking about different things....coolant level sensor or coolant temp. sensor? Either way, either one can be replaced as needed. Depends on which coolant light is coming on.

[taxidermist]

Coolant level light I belive is the light I am talking about.

[paulkramer]

Coolant level light...if that's the case, there is a sensor on the side of the radiator (on the plastic tank, believe driver's side on a '98 3800) that I replaced on my '98 when I had similar problem. Cost either $30 or $60 from dealer (I know, big difference, I just can't remember which!) It's an easy job, except of course for the darn coolant that leaks out if you don't drain some out first. There's a little retaining clip - remove that (and of course the electrical connector!), pull the sensor out, installation is the reverse of removal.

[Ruley73]

I was actually talking about the coolant TEMPERATURE sensor. A bad coolant LEVEL sensor probably wouldn't cause your temp needle to move like it does. It only reads the presence of coolant, not it's temperature. so I doubt this is your problem. I would check for air and/or a leak in the cooling system before replacing any parts. The air in the cooling system will cause both sensors to give intermittent readings because of the intermittent presence of coolant. Of course, check the coolant level for yourself and make sure it really is or is not full. Either of the two sensors can trigger a service code. If your "Service Engine Soon" light is on, get the car scanned somewhere and see what codes come up. Although, it is also possible that they won't. If that light dosn't come on, no codes are stored and none would come up if you got the car scanned. If no codes are present, I doubt any of your sensors are bad.

I thought about this a bit more and realized that there are a few more possibilities....

Your cooling system is almost due for a flush if it has never been done. The Dexcool antifreeze is notorious for breaking down and sludging up before it's recommended change interval at 5 years or 150K miles, whichever comes first. If you have an early 2000 model (which would actually have been built in mid to late 1999 - check your manufacturer date on the driver's door to verify this) this would be right on par. I would probably do a coolant flush and fill no matter what. It may not be causing your problem, but your car is (or almost) due for it anyways so you really ain't out much. If you do this yourself, only use Havoline or genuine GM Goodwrench Dex-Cool antifreeze, not Prestone (or any other stuff for that mater). They are both GM Dex-Cool approved. However, I've heard from some people in the know that the Prestone formula is not the same as the Havoline formula and is inferior to it. If you even look in your owner's manual, it says to only use GM Goodwrench DEX-COOL or Havoline DEX-COOL coolant. It does not say "or equivalant" like it does for the other fluids and lubes.

One last thing that could be your problem is a bad coolant reservoir cap. It may not be holding pressure. The lack of pressure will drastically lower the boiling point of the coolant and cause steam to form in the cooling system. Steam is air and it will cause intermittent readings from both sensors, thus causing the coolant light to blink and the temp gauge to fluctuate. Check and see if it is boiling over (past the cap).

I had this problem on a '95 Saturn SC2 I once had. It boiled over all the time even with properly mixed antifreeze. I replaced the thermostat and that didn't help. I replaced the cap and replenished the antifreeze and didn't have any trouble since.

I hope you found this helpful and maybe educational.

[taxidermist]

Yes I did thank you very much. I am going to have it flushed and get a new cap and start there.


Thanks!