I'm still trying to track down my coolant leak. (I've made like 4 posts about it ) Anyway there is no coolant on the ground but yet every day I have to put a good amount of coolant in my car. I drive to school which is 7 miles and when I go to leave in the afternoon my low coolant light is already on. No coolant is on the ground though. I hooked a pressure tester or whatever it's called to my radiator and pumped it to 18 pounds and it didn't loose any pressure. S I hardly ever use my air conditioner but today I turned it on and there was a strong scent of coolant. It was a pretty strong I was thinking heater core but my passenger side floorboard is dry and I lifted the carpet and it seems fine under there also. For as my coolant as i'm losing the carpet should be soaked if it's heater core. Also I filled my radiator up earlier tonight and I drove about a mile at the most before my low coolant light came on. I really don't even want to think about a blown head gasket. I'd rather try everything else first.
So what else could it be?

 

I read that the waterpump could be slightly leaking though the weep hole or something, then it burns off, which is why you don't find anything....and smells like it's coming from your heater core or AC.

I put in some stop leak (x2) and it stopped the smell for now (about 2000 miles so far) ...I'll probly need a new water pump later.

I wasn't crazy about the stop leak, because I don't know if it can degrade radiator cooling efficiency or not...but I had really had it with the fumes last winter, yuck!

Good luck!

 

If you smell coolant coming out the vents, it's usually from the heater core. The carpet does not have to be soaked for it to be seeping. I would take a look at it.