Dan: Did some research for you:
That bottle is called a “degas bottle”. The guy reported “with my bird, I had Hair line cracks in the bottle. They were not visible until the bottle was removed. “
Another owner said “I realized that the DeGas bottle was leaking at the threads because it was loose. I think I was at the gas station and was checking the PS and oil and may have loosened the Degas bottle top and realized it was under pressure and stopped. I think I just left it a little loose. So, I did remove the bottle and cleaned it up and put it back in after finding out it has no cracks. It has not leaked since. “
Another, I agree, The bottle seems to be a weak point on these cars. Several, mine included, have had theirs replaced due to the plastic cracking."
____________________________________________________________
Another potential for you: “There is a purge/bleeder valve behind the left front wheel well, when my
dual control valve that controls
A/C and heat for driver and passenger went a year ago and was replaced, I had a leak behind the left front wheel, when I returned to the dealer, that is what it was, the purge/bleeder valve wasn't tightened all the way after they refilled the water and coolant, at that time they replaced the valve as they stated they sometime will not seal completely after age. Just an idea of something to check”
“The heater "purge" valve on our '03 is on the firewall near the
master cylinder. A small rubber hose to nowhere. Has a plug in the end you can turn with your fingers or a screwdriver. It has scalloped edges and a screwdriver slot.. Check that to see if it’s wet. Make sure it's tight
Then to purge, bring car to operating temperature, set heat to 90, and carefully open valve to bleed air. Repeat until no more bubbles escape. There is a technical service bulletin with these instructions from a
shop manual, maybe on site.”
Finally, “I had a leak from the rear of the engine and nothing I did helped. So, I broke down and brought it to the dealer (NP Lincoln) and they found the problem easy enough. It was a hose/tube UNDER the
intake manifold. It only looked like it was dripping from the back of the engine. They had to take the manifold off, replace the tube/hose, then put new gaskets on the manifold. All told it was $850 I think if not a bit more...
parts was about $100. I don't think I would have fixed it myself even if I knew what it was. “