Wife's car, Car runs fine, no codes, etc, it's an oil drinker (doesn't look like it burns, plugs are super clean), now looks like a coolant drinker, may 2007 MCS Coupe. 40k miles. Had water pump replaced 8mo ago at about 35k miles due to leak that got progressively worse. Had full system flush then, so was full at the time.

Now coolant is down to min level, I have poked around, watched under car, ran for a while then let sit w/o AC on and I don't see any drops or obvious leaks. Oil color is normal, nothing odd there, and ODB codes show normal operating. Given the length of time I'm thinking it's the thermostat housing with a very slow leak that is just burning up as it leaks, not dripping on ground. I need to get up in there and see if I can find it...

Thoughts? Any other places to check out?

 

Thermostat housing is a good start.

 

shine a flash just below the housing, mine had dried coolant just below it on the engine.

 

Def check the thermostat that is the most common leak.

Also recheck the water pump, you had it done long enough ago that it may be on of the leaky plastic pumps. We now have a ne aluminum pump that should last much longer
http://www.waymotorworks.com/water-p...8-r59-r60.html