Recently I repaired my intake manifold nipple/inlet that had broken off on my 2011 Crown Vic. Since then I’ve developed a small coolant leak on the other side where the gasket is seated which only leaks when I run the defroster.

The heater works fine. It blows hot. No coolant smell inside the cabin. And no leaks in the lines anywhere visible. Do you think the intake manifold gasket this is culprit causing the leak? Or could it be something like a heater control valve or heater core?

I don’t see the symptoms but then again I’m new to diagnostics. I’m thinking maybe when I run the defroster just enough pressure is put on that the intake manifold gasket to make it leak in that spot. That’s my theory. Just as temp fix I did use RTV sealant in the crevice of the leak. Any thoughts?

Also I searched and searched for a new OEM intake manifold. No one has them. Not even the dealerships. Only thing you can find is cheap after market parts like Dorman which are prone to gasket failure after 3 to 5 years. So I looked on Ebay and found an used OEM intake manifold that came off a 2009 Grand Marquis with 47k miles on it.

The part looks brand new. It even has the OEM fuel rail with injectors already on it which will save me the headache and time when I replace the intake manifold. I ordered it. It cost $150 which is an absolute steal for all of these parts. I also ordered Fel-Pro gaskets for $30.

Do you think it’s necessary to carb clean and change the o-rings on the injectors on this fuel rail with 47k miles on it?

Sorry to jam so many questions into one section. Just trying to learn and much as I can. Thanks