Where'd my coolant go?

[Si|v3r72]

Suddenly yesterday my engine started running much hotter than normal. So first thing I checked was all the cooling system stuff: coolant level (was low, couldn't tell how low), tubes, connections. No leaks. Had the system flushed and filled in the spring.

I thought that maybe having filled the system in the spring, then not using the heater until this week caused my level to go down just enough to where it wasn't cooling properly. Turns out I was low by 3 quarts or so!

Is this change in level normal for just operating the heater for the first after a coolant fill?

[Ed]

I had a similar problem once. I would fill the radiator and after a couple of weeks it would be low again. It slowly got worse and I eventually found out that I had a warped head. The coolant was slowly leaking between cylinder #3&4. My exhaust was mostly steam and the car wasn't running properly.

I hope this isn't what has happened to you.

[Si|v3r72]

Well I just changed the oil & filter last weekend and there wasn't anything unusual about the old oil. The car runs fine. I topped off the coolant and the overheating problem went away.

I was just surprised that it took that much.

[2ManyZs]

It could have been just a lot of trapped air somewhere that caused the coolant drop. That's why it is always best to re-check your coolant level after any type of repair work where you have drained coolant out. Once you re-fill it it will trap air in the lines and it will take a while for it to make its way back to the radiator and be released.

Hopefully you don't have a leaking headgasket.:tapemouth

A leak down test would be one way to find out if you do or not.

Heaters are usually where any trapped air will reside, since the valve prevents any coolant from circulating when you are not using the heater it can stay in there all summer until you open the heater valve and circulate coolant.

Re-check your coolant level after a couple more drives and if the coolant level keeps dropping you have another problem.