At the risk of potentially repeating myself, since my first post is either still awaiting moderation approval, or was deleted…

I went to check the coolant level in my wife’* ’94 Camaro yesterday (cold motor), and when I opened the reservoir cap with the attached, funky plastic dipstick, I noticed it was completely full, a condition I have never seen before. As you know, the coolant dipstick has a series of cutouts near the bottom end to gauge the reservoir level. I asked my wife if she had filled/overfilled it, but she said ‘no’. I then popped the radiator cap, and saw that the radiator wasn’t even half full. This seems completely backwards to what I’m accustomed to. All my previous vehicles had the reverse situation: radiator full, and reservoir within a certain range, with plenty of room to spare.

Curious, I wanted to see if the system would “burp”, so I fired up the engine with the radiator cap off. After a few minutes, I could see the thermostat had opened, and the first tiny flow of coolant began. However, while the coolant level in the radiator very slowly began to rise, there was no “burp”, no drop in the level within the reservoir.

I allowed the motor to come up to operating temperature, and waited for the electric fan to kick in. By this time, the coolant level in the radiator still hadn’t reached the top, but the reservoir level hadn’t changed. Puzzled, I turned off the ignition, only to be witness the radiator starting to puke coolant out of the top. I’m guessing that, since the water pump was no longer circulating coolant, the residual heat caused the radiator to “burp”, and about a quart of antifreeze ended up on my garage floor. D’OH!

At any rate, can anyone help me understand what may be going on? I mean, the car runs fine and doesn’t overheat, but why on earth would the reservoir be completely full, while the radiator isn’t even half[/] full.

Thanks in advance.

Not sure what'* going on with your posts. I'll look into it. I responded to your other post with: Check the radiator cap. If the return plug isn't working right this can happen.