I'm wondering if anyone has seen this problem. I have a 2005 F150 4.6L Romeo engine that had coolant in the lower intake manifold. I bought this truck with timing chain issues and have resolved those issues. On start up after replacing the intake manifold gaskets, it ran great with no issues. After a few minutes, steam started pouring out of the exhaust and that burning coolant smell. The coolant was in the intake port on the closed valves. No sign of external leakage anywhere else. I haven't taken it apart again but it is acting exactly the same. The intake is aluminum with the lower being plastic. Last time the intake was off I pressure tested the PCV fitting on the back since coolant flows through it. Anyone out there have a strange one like this? Seems like I get all the weird ones.

 

I would assume that the gasket didn't seat properly or you have a warped intake. A pressure tester might help you find the leak. Also, am I reading correctly when you say coolant is flowing through your PCV

 

Yes, the PCV fitting on the back of the intake has 2 small coolant lines going to it. 1 from the heater tube that runs under the intake and the other goes to the front of the intake next to the other heater hose. The PCV hose runs to the right valve cover. Based on the way it runs and the fact that there is no external leakage I have my doubts that it is the intake gasket. If I take it off again I will fabricate something to pressure test the manifold off the truck. Very strange!