I've got an '01 stock XJ. Had it for 4 years now, runs great, my everyday driver. I do standard maintenance but not all that regularly.

Anyway, my coolant continues to disappear. Not sure where it's going. No big puddles under the jeep (more to this I'll get to in a min), no sign of the head cracking (other than the lost coolant), power is fine. What could it be?

The one puddle I do consistently get under the jeep is almost under my heater core. I'm wondering if this is the culprit. However the water comes from what looks like a line stubbed out just above my oil filter. Not sure what this line is for but it bleeds out moisture. Any idea what this stubbed line is or where my coolant is going?

Coolant loss is about the amount of overflow tank every month.

Here's a pic of the stubbed line.