Coolant issues just baffled an dumbfounded (SOLVED , its fords fault)

[ataw10]

I guess ill start here i have never in my life been so stumped for words on finding this issues this will be a long post so i have a 2003 mount , 4.0 sohc . stock engine nothing modified.i have been having terrible over heating issues.
Things i have checked an confirmed 100% working

radiator- flow rate tested 95% flow , tested with cold an hot as well as checked with my thermstat gun. no cold spots front or back.

water pump - checked flow rate is bassicly 100% , it was changed cuz i was runing out of ideas. so thats fine.

heater core -no clog it cant i just put a new one in anit even been able to use it cuz over heating

exhuaste flow- checked as well as ran open exhuast as a last resort no go still over heating!

the plastic thermostat housing on these things (god whos idea was that really???) - no clogs check inside an out seal is proper

engine coolant tempture sensor on thermastat housing - ohemed out an check , confirmed with tempture gun its accurate , as well as the boiling water coming out yea it works

unable or sure how to check coolant ports on the block , or how to clean them no idea proper name for them. so if you guys dont have ideas next guess

checked system for gasses from the headgasket possible leaking no gasses coming in

pressured tested system no leaks or loss even when overheaitng pressure remains steady it gets way to high so i shut off car to provent damage !

resovore cap has been replaced to rule that possible leaking pressure it was only $3 for a new one so i did it why not

made sure on every test to make sure air was removed so dont think its that.

the thermstat in the thermastat housing removed from it place in boiling water it opens an closes

my only solution that has worked for me an i have zero idea why ! is dont keep the thermostat in the , thermostat housing. I leave it out after 10mins its gets up to normal operating tempture . (im worried about this because this isnt normal !) i am trying to find the culprut because running it without a thermostat is just avoiding the main issue however with it getting up to temp blowing hot air from heater perfectly an no running issues should i be concerned? or just say screw it no thermostat an keep on going.

i almost forgot i have drained oil 3 times as doing my test to figure out what wrong an checking for coolant in it nope , clean as a whistle.

 

[ataw10]

if you got other forums i can possible post to find resouces or such . to countuine my hunt to fix this darn engine i am all ears <#

 

[ataw10]

i have found the soultion an you can blame ford !

to anyone who is reading this an you got in to the issues i did 1st remove the thermostat from the plastic housing. put cap on run car if stops over heating good on to step 2
step2 check vacuum hose that goes to the heater inlet port has not fallin off or been damaged.
step 3 turn heat on make sure it works

if all are good to go congrats you have found your issue

its the plastic housing that ford made mostlikely the inside of it deformed that was my issue thermostat couldent open because the plastic metaled

throw it away go online spend $50 get a metal one forget about this happening again. mines fixed

WHOS IDEA WAS IT TO USE PLASTIC FOR THE GOD DARN THERMASTAT HOUSING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[ataw10]

this is the secound time the thermastat housing has failed me in less than year do not GET PLASTIC AS A REPLACEMENT JUST DON'T SEROUSLY DONT !

 

[J.Rovirosa]

The second Ford OEM housing on mine (new gaskets/orings and thermostat also) has probably 10-15k on it and appears to have a small leak at the seams again. The top of the housing where the thermostat sits appears to be warped and doesn't sit completely flush to the body of the housing. Never been overheated, cooling system otherwise seems fine. Aside from this just being a piss-poor design, I'm guessing the cooling system may be pressurizing with exhaust gas, which I'd think the coolant tank cap would relieve. Unless the cap itself is faulty and maybe not relieving normal system pressure.

 

[TechGuru]

RockAuto sells the metal outlets.

More Information for SKP SK121259

www.rockauto.com

Install your own Motorcraft thermostat and temperature sensor. Don't use the chinese ones that come with it.

 

[J.Rovirosa]

Going to throw in a vote for the Simmons aluminum t-stat housing; nicely made, one piece, and they shipped it really fast.