Okay, I'm a klutz. I've changed a lot of thermostats over the years, and this is the first time I ever had a housing break. This is on my 1985 F150, 4.9.
I have no idea what I did wrong. I could see no tabs or anything on the thermostat that may have cocked it off of alignment. The manual says to turn the thermostat clockwise in the housing, and it will click in place? Well, I could neither hear, nor feel any click, and saw nothing that looked like it would make a mechanical lock. I'm lost.
Anyway, I will have to track down a new housing, and my second question, what is the name of the part that holds the heat sensor unit that is attached to the housing? I tried turning out the old one with a pipe wrench and a vise, and it will not move a bit. SO, I will need one of those, also.
Any help or suggestions are very welcome!

 

Hey ric yes that happens ,i do belive your talking about breaking your coolant housing, the coolant temperature switch is what it is called . It sends a signal to your computer(feedback carbuerator).All work together. The housing is what they call pot metal(or i do )and you can find one from a autoparts salvage yard. Try soaking the threads pbblaster , kroil, wd 40.Sounds like when you installed the housing the thermo, got out of line and when you tighetened it , pressure broke it .Always remember use an anti seize on parts like that , Anti seize can be used on alot of our truck parts .Over the years i believe some thermostats had a sticky gasket to help hold that part in place Good luck TR

 

If the thermostat slides down, out of place, it will crack when you tighten it down.

Compressor Works/Water Outlet (814976) | 1985 Ford F150 1/2 ton P/U 2WD 6 Cylinders Y 4.9L 1BL | AutoZone.com

Duralast/Coolant Temperature Sensor (SU201) | 1985 Ford F150 1/2 ton P/U 2WD 6 Cylinders Y 4.9L 1BL | AutoZone.com

 

Sorry for the bad picture. What I'm asking about, is the part sticking out on the right. I've got Kroil soaking it, but it has made no impression yet.

 

The thermostat housing can be purchased at most any auto parts store. Last time I picked one up (about 5 years ago), it was $15. They almost always break in the same spot. Just be sure to wire brush your head clean and down to bare metal, or it'll just break again and again.

As for the port that sticks off the side, that, as far as I know, is NOT for sale. I always had to remove mine and move it to the next thermostat housing. (I broke a few before I learned how to install them right).

When you torque them down, go in increments of 3 - 5 lbs per side until you add up to the total (which I think is about 15 - 18 ft/lbs) or it can break from one side being torqued down more than the other.

 

Thanks for the replies. I don't know what the previous owner used to seal this part on, but it is tenacious. I am going to try some heat, and if that doesn't work, off to the scrap yard I go.
Which brings up the question, what kind of thread sealer SHOULD be used on these?

 

When I did mine, I think I just used regular teflon tape.

 

Okay, got 'er fixed today, I don't see anything leaking. I had to take a torch to the connection to break things free. Thanks for your input~!

 

Good. For future readers, the housing I bought from Auto Zone was unusable, holes positioned wrong! Got a good one from O'Reillys. I learned you must use a tacky gasket sealer to hold the thermostat in place while you tighten the housing down. The aftermarket housings dont have that internal notch business that the factory one had.

 

I found mine at Napa, under $11.
I found it was much easier to get things in position with the hoses removed.