Won't seal at the bottom.

Tried rtv. Tried a few gaskets.

Tried a different tstat housing.

Wire wheel the housing clean so no left over gasket.

Any other suggestions?

 

Edge of the thermostat is in the recess on the head, gasket on the housing?

 

I have seen this happen many times. You might also want to run a straight edge on the t-stat housing and the block to make sure that it is even and you don't have any gaps.

 

Gasket on housing tstat in groove in block, yes.

I hope the head surface isn't warped, dunno why 2 housings would be warped.

I'm gonna try using rtv and gasket both and hope for the best I guess.

 

Yep, something has to be warped. I just did mine yesterday like butter....

 

I have seen them warped out of the box. Also, if they are over tightened can cause them to warp. When I put them on I put a thin layer of RTV on both sides of the gasket. Then I will wait a little while for the RTV to set up a little before installing it so it won't slip out of place.

 

^
Gasket I got from NAPA had self adhesive on one side, stuck that to the housing, little red RTV on the other side.

 

But don't forget to check the head mating surface for warp...ness.
And torqueing to spec?
Bolts ok?

If all else appears normal and has been checked, I'd saygasket +RTV (is what I did)and a proper seated thermostat
.
There is really not much else that could be causing the issue...

 

Try using a little RTV on both sides of the gasket.

 

Also, make sure you give it some time to set (see instructions on package for times) before you fill the cooling system.

 

Like scottmphoto said use a little on both sides. If it is the gasket that has the sticky side you need to make sure you peel the plastic stuff off.

When I did mine in my YJ not to long ago I bought a new thermostat housing, it was cheap and made things much easier. Another thing I do is use a tiny smudge of RTV to hold the thermostat in place around the edges.

I used the gasket with a thin layer of RTV on both sides then let it sit for about an hour to make sure it dried before I filled it.

I've seen where people don't get the thermostat seated correctly and bend or crack the housing. Its not quality metal and very easy to damage.

 

I had issues with mine sealing and found that Toyota FiPG works great. It's like super RTV. A thick coat of FiPG will seal up just about anything, just make sure both surfaces are dry.

I wouldn't put RTV on a gasket, personally. Paper gaskets and rubber seals/O-rings are intended to seal on their own. If the surfaces were perfect, a dry paper gasket would do just fine by itself.

Just my $.02

 

Yup, thin layer of RTV on both sides of the gasket. I use permatex grey, it works pretty well.
I also like to apply thread sealer to the bolts and snug them like a 1/4 of a turn after threading them in all the way.
Like said give it a hour or so to cure. Personally I'd let it sit over night .

 

ya biggest mistake is not letting the RTV half way cure before installing and the other mistake is only waiting a couple hours to start the truck... sticking RTV on both sides doesnt matter because the surface is suppose to sit flush... and it will depending on how hard you torque the bolts... i normally do that then let it sit over night...

and it is possible for them both to be cracked... i dont know if you got a brand new one but if there both used then its very possible and very common... i couldnt even see mine till it was on and torqued... finally saw where the water was coming from but still didnt see the crack...

 

I had to tq the **** out of my Tstat housing to get it to seal. paper gasket.