97 Malibu Low Coolant Light

Low collant light warning and chime comes on shortly after start-up and stays on for about a minute then goes out. Dealer can't find any problems but thinks it might be a faulty float in the coolant reservoir and nothing to worry about. Anyone have any suggestions?

Have you needed to add coolant from time to time and, if so, how often?

Never had to add coolant other than a small periodic top up at minimum once a year.

How does the oil look when you change it out? White residue/mist/smoke coming out of the tailpipe once the block is up to temp?

Sorry if this is a double post. Oil and emissions are normal. Head gaskets check out OK so I know that's not the problem. Still tend to think it'a a sensing or sending unit problem.

Mine has done that in the past when the coolant level was a bit low. It goes off after a few min of driving.

Always went away after I topped up.

If I let it persist for too long, it would stay on.

A float? um, NO. At the front of your overflow tank, bottom right is the connector for the coolant level. It's a electrical "normally on" circuit. When the coolant level drops below the sensor, the circuit is broken and the chimes/lamp get enabled. It does tell me that I wouldn't trust that dealer to pump my tires.:screwy:
It sounds like at some point your tank was filled up too much with coolant. It was forced out the overflow tube when the engine got up to temp and you've been "low" ever since? If your tank is as opaque as mine, it would be hard to tell the proper level.
I will caution you that I was adding small amounts every so often for about one year to replace the phantom coolant that had to be going somewhere...
then my intake gasket went about 5k after that. So keep an eye out for black "globs" or other dark discoloration in your tank, and the dipstick for the milky white. That means you've got a job ahead of you.

Since I just replaced my water pump today...place a piece of clean cardboard under the engine. See if there's any orange on it the next time you go out. I discovered a small leak at the gasket for the water pump. Too small to see. It was the smell that gave it away and led me to the leak. The water pump is under a black "cover" that the serpentine belt turns it with. It also allows leaking coolant to drip onto it and deflect it back to the block etc. so it was a devil to find. And, that black pulley shell is a devil to get off!

Bottom line is that stuff is going somewhere, it just doesn't evaporate.

Hope that helps.