Broken thermostat housing bolt

[shane10]

Hi all, I recently noticed a slight leak in the lower thermostat housing of my 2002 ford explorer. Went to the dealer for all the parts, no problem. Disconnected all the hoses and sensors, removed the top housing without a problem.
When it came to the lower t-stat housing, 2 of the 3 bolts came off with little resistance. The third however had a severely rounded bolt head, grabbed the bolt extractor socket, which proceeded to DESTROY the remaining stub with nothing left to grab onto, i decided to remove the entire bolt head to allow me to pull the housing off and deal with the remaining bolt.
The bolt itself doesn't thread into the housing, it is smooth with a threaded bottom that screws into the engine (not sure what part), so I was thinking in removing the entire bolt head i would be able to just slide it up and off. NOT THE CASE. I am able to get a little wiggle to left and right, but when i lift, nothing happens.
I was thinking of getting an easy out extractor, but after reading about many negative comments, and the fact the bolt is 5/16 (small) decided against it for now.
I have been working at it for hours, sprayed with PB blaster many times, wiggle to try and break lose, no luck.
Any suggestions on how to remove the bolt? And as to why the housing won't lift, even though it is not truly threaded onto anything.
Thanks
EDIT: I have a new upper/lower t-stat housing waiting to be installed, so not worried about damage to the housing during bolt removal, I will break the existing one to BITS if I have to

 

[Number4]

The lower housing has three tabs that "click" into the block as I recall. Are you sure it isn't these three tabs giving you resistance? How hard have you tried pulling up? lol at the bottom of your replacement piece.

 

[shane10]

It may be, i've tried pulling upward pretty hard, there's not much room to work with to get lift.
Maybe ill try wedging sometime under the bottom of the housing to lift free/break those tabs.
Thanks

 

[swshawaii]

Sounds like the broken bolt is seized in the pressed in metal sleeve. Take a look at the new housing and you'll see.

Don't gouge the sealing surface if you pry. I'd break it apart with a cold chisel, small hammer, and safety glasses. GL

 

[shane10]

Any idea how to un-seize it? As i've said it has received many sprays from the PB Blaster with sufficient time to soak already.
I'm able to move it to left and right as much as the assembly allows me before hitting the alternator (left) and engine (right).

 

[shane10]

Fixed

UPDATE: Was able to remove the housing from bolt with about 3 hours of elbow grease, rocking back and forth, cutting some of the housing to make clearance to lift, and countless douses of PB Blaster.
I have gotten rid of the giant pain in my ass, and am ready for reassembly.
Thanks for the help!

 

[LoKo498]

Does anyone know what size bolt these are? Maybe I can buy them from the Fastenal store.

 

[swshawaii]

^ V6 SOHC? If so, M6 x 74mm sound correct? Have a removed bolt to match at Fastenal?

Thermostat Housing & Related Parts for 2002 Ford Explorer