Losing Coolant

I was just wondering if anybody could help with this issue (maybe the water pump is on its way out? Though there are no leaks I see)

I got my 94 Caprice Lt1 9C1 in summer of 2007. I have put around 2800 miles on it since then. This happened twice so far.

I noticed that the temperature (which usually stays around 1/3) went above half, and up to just below 2/3. When I checked my coolant resevoir, the coolant was near empty. I bought the premixed coolant and filled it up.

It went back down to 1/3. Then about 1800 miles later, the same thing happened. Filled it back up, and now its fine. Maybe I didn't check hard enough for any leaks but didn't notice anything.

I do hear a bit of a noise while the engine is running (its a consistent type noise with a bit of squeeking I think).

Any possible suggestions?

Like you said, you wernt sure the first time so fill the jug and keep an eye on it for a week every day.
as for the noise, check your belts for starters.

Sounds like you're either burning it, or losing it into the engine oil.

If you want to check your water pump using the "stick" method, just place a piece of wood against it and the other to your ear and listen for excessive uneven noise. I piece of broom handle, dowel or firring strip will do. Listen to other things like the alternator so you can tell the difference between bearing sounds.

But I doubt it is the water pump, usually they are catastrophic spontaneous geysers preceded by an ungodly "no stick required to hear" bearing noise.

Look for small parasitic leaks like hose connections at the radiator, the petcock for seepage, heater control valve, thermostat housing. Install a new radiator cap.

If nothing shows up, I would dump a tube of Solder Seal radiator sealer into the radiator and keep an eye on it. If it still leaks, have the cooling system static pressure tested next.

Bob