low coolant light always on?

Question

i have a 95 oldsmobile surpreme and my low coolant light keeps coming off and on. sometimes it just stays on and sometimes it doesn't come off at all. I popped the hood and my overflow tank is full, so there fluid isn't leaking out. no visible drips or puddles on the ground when sitting for long periods. Could it be possible that the fluid isn't going from the overflow tank to the radiator, therefore the sensor is thinking the radiator is empty? I just filled the radiator the other day and it's still coming on (the light). any ideas?

by the way, where is the sensor so i can clean it or check it?

Answer 1

You mentioned you added fluid to the radiator the other day, which implies it was low. So when it cools, you need to look in the radiator again. The radiator can have a coolant level sensor as well, and will ost likely be about a third of the way down the side of the radiator under the filler cap.

If the overflow is still full, its obviously not getting pulled back in. Clean the radiator cap and where it goes in carefully with a rag. If the rubber is cracked, replace it. The hose could be old and cracked going to the overflow.

Or worse, you have a leak, and that is breaking the vacuum, preventing the overflow from keeping your radiator full (and why it was low in the first place). Look on the ground for leaks. Check your oil filler cap for foam and gunk that shouldn't be there if it is leaking at a head or manifold gasket.

Answer 2

It appears that you possibly have a bad sensor. Could also have a bad radiator cap. If the cap doesn't hold pressure then the water will go to the resivoir and not return back to the rad when the rad cools. Water heats and expands, cooling creats a vac in the rad pulling the water back in. If the radiator cap is not retaining pressure then it will not allow the vac either. Its not hard to test the cap and you can possibly get it done at an Auto Zone or other reputable auto parts store. It will be cheaper to replace the cap over the sensoe.
The level sensor should be in the radiator just below the the level of the upper hose on one side of the rad or the other possibly pointing to the engine and having two wires coming out of it. Hope I've given you some usefull info and would ask you to let me know. Thank you.

Answer 3

low coolant sensor is attached to the side or bottom of the same overflow tank. before replacing the sensor, make sure that your problem is not related to a false connection by moving the sensor cables while somebody else is watching at the dashboard for the light indicator. The sensor retails for $57 at advance auto-parts.

Answer 4

You may be right about the coolant not getting to the radiator, but it could also be a bad sensor (or sending unit). Sometimes the thermostat will stick and cause this problem. If I were you I would get it checked out very soon.

Answer 5

I had the same problem recently with my 96 Lumina. I had to replace the sensor...it wasn't cheap either. Now I don't have problems with the light coming on.

The sensor is in the radiator. Good Luck!

Answer 6

Check the radiator first to make sure it is full. Just because the reservoir is full does not mean the radiator is also. If you are low then there is your problem If it is full then replace the sensor.

Answer 7

the sensor sometimes sticks on these.you have to replace the sensor or very lightly tap next to the sensor to get the light off

Answer 8

have a mechanic install a new sensor and check the system.

Answer 9

replace the sensor....