The car whispering that its getting low on coolant

Well, this was my fault, not checking the level in the coolant recovery bottle for a couple of months. I really don't have any excuse, because last fall I pulled the bottle out and removed all the mineral buildup on the inside that prevented getting a good look at the level. So all I had to do was shine a flashlight down there and check it. Duh. Before, the only way to get a reading was to look at the bottle from under the car when I changed the oil, or put a long stick in the top after unscrewing the cap where the tube from the radiator goes in.

Anyway, I always watch the temp gauge closely. The needle remained right where it should be, but trouble was brewing, because the level in the bottle had gone to zero, and now the level in the radiator was down a little, but not enough to make things run hotter. So all appeared to be well, but it wasn't. The safety net (the excess fluid normally kept in the bottle) was gone. The next step would be a rise in temperature, which as long as it got caught, would be ok, but maybe inconvenient. I'm not even sure if the car has a warning light for high coolant temp, but I sure woudn't want to see THAT.

But the car was trying to tell me something, very quietly. I just didn't put it together, because the symptoms didn't remain. Like whispers in the night. The heat didn't seem to be quite hot enough once, but I slid the temp control a little further to the right, and then it was fine, but I remember thinking it was a little odd. Then, the fast idle valve malfunctioned and the car quit a couple of times on starting, but then it was ok. Finally (duh again), after I had turned it off and was sitting in it briefly, I heard the distinct sound of gurgling. Gurgling? Air bubbles? Time to look at the coolant! There you go.

Moral of the story....first, check the bottle more frequently. Second, lack of heat means there might be some air instead of water in the heater coil. Third, the fast idle valve will malfunction with that same air-instead-of-water combo. Fourth, gurgling means air.