2006 2.2L with 230,000+ miles. I'm going through coolant about 1 gallon every week (300 miles roughly). I had the oil tested and there is no coolant in the oil. There is not 1 drop on the garage floor after sitting all night. I'm guessing cracked head or head gasket although I'm not seeing the tell-tale 'white smoke' from exhaust at idle. The passenger side floorboard is dry so I don't think it's coming from the heater core, but I do "smell" the dexcool in the cabin and between fills I hear the sloshing sound of coolant at the dash.

What do you guys think? Next steps?

 

My guess would be head gasket/cracked head. Some part stores sell a tester that tests for combustion gases at the coolant fill cap. It would confirm an internal leak.

 

Here is the tester

 

I'd have a look at the spark plugs. I'm thinking it's burning it if it's not going in the oil..

 

X2 to the combustion gas test kit, and X2 to the plug check(look for one that looks suspiciously clean).

Plus, check your oil for a "chocolate milk" look and milky deposits at the top of the dipstick and under the oil fill cap.

And you might consider a compression test, plus pressure testing the cooling system.

 

If you are smelling coolant in the cabin, check the inside of the windows for a build-up of moisture, or what looks like smoke coming out of the heating vents on the dash. The floor will not necessarily be wet if the heater core is leaking - the moisture may be trapped inside the heater mechanism causing the sloshing sound you hear.

 

Or the sloshing/gurgling may be air entrained in the cooling system, it can be a "tell" when the coolant is low too.

 

True that 843de. When the heater core in my other car went last fall, at first I thought I had a fire in the dash with the "smoke" from the vents, and the smell was nasty!!!!!

 

I remember that, "The Revenge of The Avenger" incident, I bet your back is still sore from the under-dash contortions required to fix it.

 

A other less catastrophic guess is water pump. The weep hole is on the top inside a well, so the coolant tends to kind of dribble and steam off rather than drip on the floor.