Whats going on with this low coolant light

**ladyb** · 07-06-2008, 08:19 AM

I need some help with my 1999 buick century. Ever since I replaced the original water pump with a aftermarket one, the low coolant light comes on and stays on until the thermostat opens, then it will stay off. The coolant level is never low. I have been told there may be air in the system. My question is what is the best way to bleed the air out.

**njlimbaugh** · 07-06-2008, 07:41 PM

If you've driven the car any distance at all it has bled itself. When working with the cooling system I always fill it as high as it will go, then run the engine until it reaches operating temperature and the thermostat opens. If in doubt, keep an hand on the upper radiator hose (watch out for the fan!) When the hose gets too hot to handle the thermostat has opened. At this point you will probably notice the coolant level going down which means the air is being expelled. Add coolant until the level stops receding. It's full.

**Gray Whiskers** · 08-08-2008, 05:53 AM

I had the same thing happen on my 98 park ave. You must bleed the air out. There should be a small brass screw on top the thermosate cover. Open it and run the RPM'S up after the engine is hot. You will see the air come out. You have to give it some time. Do it a few times.Make sure your overflow tank is topped off so when the engine cools down it will suck coolant back into the rad. Hope this helps you out.

**Tom Gallagher** · 08-10-2008, 06:50 AM

I know that this is summer and a lot of people forget to turn on the heater which expands the volume of coolant. Just a thought. It could be a common oversight. Air could be trapped in the heater core.

**petty** · 08-14-2008, 07:21 PM

It was really possible that the problem is on the air in the system. Try tapping the reservoir to remove trapped air bubbles from the low coolant sensor. Is the electric cooling fan working? As far as I know, there were valves in the cooling system that releases the trapped air from your engine.

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**series40special** · 08-15-2008, 04:12 AM

Very important to check the intake manifold gaskets,leaking is a very
common problem with the 3100-3400-3800 V6 motors. Look underneath
by the oil filter and a/c compressor. If there is dried coolant or oily residue
underneath,especially by the oil pan,it's leaking.