Update: found thread w/answer. '11 Overheating and coolant leaking from BELOW thermostat housing!

[hawkman71]

My 2011 Exped 5.4L is overheating. it's now my 17yo's daily driver. He lives at home. Was going to replace the thermostat but first wanted to diagnose.

I started the vehicle and watched it warm up. It took quite a while before the fans came on. The gauge showed temp a little past halfway. Took it for a drive and as soon as we got going, the temp climbed fast until it maxed out. Then the temp warning light came on. We stopped and I found that the top radiator hose was indeed hot. (It was cold prior to leaving the house, with the fans running and engine hot.) Note that while driving, and the temp gauge maxed out, I turned on the heat in the cabin at max with max fan speed. The air was not hot.

Got home, turned it off, popped the hood, and heard hissing and bubbling coming from the engine bay. I looked and the coolant is leaking from BELOW THE THERMOSTAT HOUSING. (see photo).

At the moment, I'm considering replacing the thermostat to see what the effect is. However, I don't truly know what's going on. I feel the leak is at the gasket below the thermostat housing. Thus, it has been comprimised and therefore needs replacing.

Is there a chance that the thermostat is almost non-functional, causing pressure buildup below it - on the engine side?

Any help or suggestions would be appreciated. Thanks so much for looking.

Photo: The coolant is coming out near the GREEN LINE.



I believe the leaking is where Part #12 meets the gasket, number 13 (right-hand #13)




Terminology: there seems to be conflicting info online as to what the parts are called. I call the piece above thermostat the water outlet. The piece that the thermostat is nested in is called the thermostat housing. However, I've also seen it called the water bypass pipe.

 

[hawkman71]

Gosh, sorry guys. I found a thread here that explains it. I had opened it in a new tab but failed to get to it before posting.
Here's the link: Coolant leak under thermostat housing?

 

[bloodhound]

Gosh, sorry guys. I found a thread here that explains it. I had opened it in a new tab but failed to get to it before posting.
Here's the link: Coolant leak under thermostat housing?

Yup, pretty common. Replace the thermostat 0-ring and should be good. Though the coolant crossover O-rings are probably right behind it on failing, I would recommend doing those too.

 

[2012XLT]

I just paid a shop $1700 to do this exact fix on my 2012. There is a way to do it without removing the intake manifold - there is a video on youtube about how to file down the edge of some component to allow the pipe to clear it be removed without removing the intake. The shop would not do it that way. Recommend you research it to same some cost.

 

[2012XLT]

Here's the video I referenced - https://www.youtube.com/watch?v=2lUM9n2b4mQ. If the link doesn't work just search for "

Ford 5.4L 3 Valve Coolant Crossover Gaskets, Both Replaced -The easy way"​

 

[bloodhound]

I just paid a shop $1700 to do this exact fix on my 2012. There is a way to do it without removing the intake manifold

I hate to say it but you got taken on that one. The intake absolutely does not need to come off, and nothing needs to be filed down. I did mine myself, it took less than 2 hours total.