1995 960 Coolant gone/Temp gauge

[techedbob]

I was driving and car was starting to make noises, the a/c was running so I turned it off thinking that might be the problem. The car noises got louder and then oil light came on, pulled over and shut off car. I raised the hood and noticed that there was no coolant in the tank. The temp gauge was about half way up (usually where it is). I got about two gallons on water and put into to the tank. Started car and it ran find. This morning I went and got under the car to try to find the leak, there isn't any. (where did the water go). Also the car started fine. I did notice that the temp gauge was at the normal running position and then upon starting the gauge dropped to the cold position and then jumped right to it normal running position. I am confused on where the coolant might have gone and why the gauge jumped to the normal running position?

[regent]

The coolant could slowly go quite a few places: into transmission oil, engine oil (with immediate consequences), or out through exhaust or simply through a small leak in the rad or a hose into the air...
If you were able to put in 2 Gal. then the system was entirely empty. I would check for coolant in the engine oil; what about any unusual odor/color from the exhaust or unusual transmission behavior?

[techedbob]

I will check thanks

[lummert]

Temperature gauge doesn't work properly if the gauge sender isn't surrounded by coolant, as in the coolant is too low.

[difflock54]

Check for wet carpets around the heater core also.
One should notice a coolant smell if that is leaking.
Also check the coolant reservoir for cracks and its cap as the seals fail allowing coolant to leak out under pressure.