New coolant thermostat housing question

[Lukas2009]

I've ordered a new upper and lower thermostat housing, thermostat and o-rings.
Everything original by Motorcraft.
When I press them together by hand there still is a huge gap between the upper and lower housing.
Maybe someone here who already replaced a cracked housing can tell me if this is normal or not.

 

[thebrakeman]

Seems like the 3 bolts will compress the rubber seal on the thermostat itself. It needs to be a compression fit to get a good seal, right?
Remove the thermostat, and put the 2 housings-pieces together. I'll bet they sit flat.

 

[Dag06XLT]

The bolt have very low torque spec so use a torque wrench to get a proper seal. Your top picture shows the rusted screw too tight and smashed down which will warp the housing. The seal is around the thermostat not the outside by the screw holes so a small gap is fine there. Did mine 9k miles ago and no leaks.

 

[Lukas2009]

Yes, the rubber o-ring on the thermostat is what will seal the housing.
Without the o-ring and thermostat the housing-pieces sit flat together.

The old housing on the picture is the first one and had never been replaced before.
And that is what makes me wonder. If I would torque the housing like Ford did, then we are not talking about ”low torque“.
It has to be 10 Nm (89 lb-in) for the cover and 12 Nm (9 lb-ft) for the housing.
In my opinion too low to get such a small gap like shown on the picture of my old housing, where Ford torqued the cover.

 

[thebrakeman]

Yeah, it's not a stretch to think that the original item was overtorqued.

 

[SoCal2V]

Do as suggested above regarding assembly of the upper and lower pieces. If the gap still bothers you then use a light amount of black rtv sealant around the outside of the t-stat for added peace of mind.

 

[MotorCityFats13]

one option is to drill out all the bolts that use the inserts, get longer bolts and nuts this way when you tighten them down you compress all 3 layers of the housing and nut just the top to the middle and run the risk of splitting them apart.....no matter what you can rule out the housing ever splitting again

 

[Lukas2009]

You are absolutly right. I've read about this in another thread and will use the bolts and nuts method.

It will look like this:

 

[MotorCityFats13]

when I bought mine it was already leaking so i replaced it in the first week... problem was it was cold out so I just swapped in the awesome $15 ebay special....now 14 months after that repair I can see white residue on the top and all around the temp sensors.... Im not getting the same steam from the grill with the split one but my coolant is dropping from max hot to cold every 2-3 weeks.... not sure if its the o-ring around the sensor or the housing but I really should do the bolt trick now that weather is warming up.... I try to tell as many people that I can about this little fix but still have not done it myself.... kind of makes me look bad when I am showing people what you do to prevent the dreaded splitting