How low to activate low coolant warning?

[Austin83]

2008 GMC Sierra Z71 5.3 (38,000 miles), I noticed the coolant was a little below the coolant level. I squeezed the radiator hose and the level rose slightly to about 1" below the full level. At what point does the low coolant warning go off? Not, that I'm going to let it get to that point, but I had read that the coolant level warning was sensitive. I do my own maintenance, but I'll admit that I assumed the coolant level a little below the full mark was alright until looking through my manual this evening. My coolant level warning has never gone off, my engine temperature never gets above 210*, oil looks fine, no leaks, etc. I will have to take care of my coolant level after I get home and let the truck cool down. Any advice is greatly appreciated. Thanks.

[DaveH71]

The coolant warning lamp wont go off until the coolant is below that sensor on the reservoir. There's nothing wrong with the level being a little below the full mark, as long as you are sure there are no leaks anywhere just top it back off and continue on your way.

[jhm]

2008 GMC Sierra Z71 5.3 (38,000 miles), I noticed the coolant was a little below the coolant level. I squeezed the radiator hose and the level rose slightly to about 1" below the full level. At what point does the low coolant warning go off? Not, that I'm going to let it get to that point, but I had read that the coolant level warning was sensitive. I do my own maintenance, but I'll admit that I assumed the coolant level a little below the full mark was alright until looking through my manual this evening. My coolant level warning has never gone off, my engine temperature never gets above 210*, oil looks fine, no leaks, etc. I will have to take care of my coolant level after I get home and let the truck cool down. Any advice is greatly appreciated. Thanks.

You are right, the sensor is sensitive (does that make sense?) Mine used to turn on for no apparent reason, was not low at all. Now that it is older it dosen't do it anymore. Less sensitive I guess. Just check it when cold, should be at the COLD line.

[flyboyron]

I agree, make sure it is at the cold line when cold or when it expands and fills up it will be over full.

 

It shouldn't go down much if there are no leaks.