hi there new to the forum.i changed my thermostat on my 61 f85 w/215 lastnight.i couldnt test it last night so i waited till morning .i used the proper gasket not glue.do these have a habit of warping? im leaking antifreeze from the bottom of the thermostat housing im guessing,and its running down the valley to the back of the motor. anything else i should look for??

thanx

 

well that seems much less urgent than the title indicated....but i always use high temp RTV silicone with the gasket, a small bead on both sides. i put a small bead around the opening on the manifold itself, then lay the gasket on top of the silicone (don't push it down, just lay it on, straight), then i put a small bead on the bottom of the thermostat housing itself, and then lay the housing on top of the gasket.

so it's stacked like this:

housing
silicone
gasket
silicone
manifold

don't push down on the housing to compress the silicone, just lay it all together and lightly apply a little pressure just to make sure it is all sealed. allow to dry 24hours, then go back and tighten down the screws. thermo housings are touchy, leak easily if not re-installed correctly. this is how i've had the best luck....in my experience, just the gasket itself will not work very well.

 

Is that an aluminum thermostat housing?
If so, it could be warped or deformed around the bolt holes by overtightening. Put a piece of emery paper on a hard flat surface and rub the housing's gasket surface over it. If it's not flat, that should be obvious when you look at the pattern left. Continue sanding until the surface has an even finish.

 

What he said. Also, verify that there isn't corrosion around the sealing surface on the manifold and that the clamps on the bypass hose are properly tightened. In fact, there can be corrosion on the barb for the bypass hose, causing a leak there as well.

 

And the two attaching bolts run through into the water jacket so they need sealer on the threads also...

 

Unfortunately, I can vouch for that.

 

Sealant good on both sides of gasket! (I use permatex #2 but RTV good, too.) Clean surfaces with alcohol before applying sealer. And do not overtighten. Use a torque wrench.
I actually go 5lbs under, allowing a little more should I do have a leak, which so far I havent.

 

fixed it .the tiny crevice were the thermostat sits was caked ,therefor not seating rite

thanks guys