Hey guys, due to a recent act of large pry-bar vandalism, I had to replace the radiator in my 1996 ssei. The replacement was smooth and nothing leaks. I am running pure water in it for now, but will change well before it gets cold again. I allowed it to warm up the backed off the bleed screw on the thermostat housing to bleed it while it idled. The fluid after nearly 2 months of running looks perfect, no change in level and the oil looks as it should too, only problem is the low coolant sensor on the gauge cluster pops on for much of my driving. I check the fluid at least 2 times a week feeling freaked out about it. Any ideas why this sensor thing is happening after I changed the radiator? I did make sure the low coolant sensor is connected correctly also.

Being a sensor, they can fail. Some have issues with them gunking slightly and not reading properly, some they go bad. You can unplug it if you are good about checking. Since most cars don't have the sensor, it'* not a required system.

I would advise putting the antifreeze back in. When used at recomended mixture 50/50 it not only does it lower the freezing point but also raises the boiling point (which may be cause of your low coolant light as maybe water is just steam not liquid) Lastly antifreeze is a rust inhibitor. Using water for 6 months cannot be healthy for your cooling system. Thae water and the oxygen in the water will contribute to much internal rust.

Just curious, I have the same coolant level light on all the time and my coolant is full, air bled, and reservoir level good. This light does not go off however, and I am wondering if the sensor is in the reservoir or on side of radiator (I think I saw electrical connector on passenger side)? I did hear they can get gummed up or stick so I would like to either clean it or just replace it, the dummy light is annoying.
Thanks

Couple of things here.

First: It is usually recommended that if there is an issue similar in nature as yours, however not addressed recently, we usually create a new topic, and you can link to the old one, indicating the similarities

Second: The coolant level sensor is on the radiator side tank, passenger side, between the transmission cooler lines (What you likely saw). Usually if it is an annoyance, the sensor can usually be replaced, or simply unplugged if you don't want to deal with it.

cool sounds good, I just read that in another thread so I will check it out.

Thanks