Technical Sealing a thermostat housing.... opinions?

I had stripped threads in the manifold for the thermostat housing on my ‘37. I’ve installed a couple of helicoils and am ready to reassemble. I could use some advice.
I was planning on using the gasket in the photo below. The thermostat housing has a small crater in the mounting surface as seen below. Should I use the gasket and RTV, just RTV, or just the gasket?
Really don’t feel like taking this apart again. lol

Thanks in advance.

Allan

 

Normally I say that if the gasket is installed correctly you don't need sealer. But with imperfect surfaces I would use a THIN layer of rtv on both sides of the gasket. If it squeezes out the sides then you used too much.

 

Thanks.
Is that enough of an imperfection to warrant RTV?

 

RTV will work .... I’ve had real good luck withSEAL ALL , both sides of gasket , let set up a bit , put together. Don’t run until set up for an hour or two , patience.....

 

Don't over think it.......use the gasket with Permatex Aviation Form-A-Gasket liberally brushed on the thermostat surface and manifold surface. Never did understand the need for using slippery silicone gasket creation material (and hope it cures) along with a perfectly good gasket. Been using Permatex as mentioned with gaskets for almost 60yrs. Seldom has failed me. Can't count the number of jobs I have re-done that someone wanted to be high tech, so they smooshed on lots of cool colored, expensive silicone stuff and prayed to the curing gods for a good repair.

 

+1 for permatex but also make sure that housing is flat.

 

Hold some wet or dry sandpaper on a flat surface and move the housing over it to true up the surface first

 

My only comment is that chrome housings like those made from that 'metal' corrode from the inside out very quickly. It won't be long before pinholes appear in the chrome.

 

Could not make out the small spot,but as said above sand a little till you have a better surface.

 

if it were my car, I'd buy an aluminum or iron thermostat housing, and put that chrome pot metal one in the trash can, where it belongs.

But I'd also use Permatex Aviation gasket sealer on both sides of the gasket, with the new housing.

 

I've had good luck using RTV in these situations by costing the gasket with a thin layer, bolting the housing finger tight, go away from it for an hour, then snug it up. Don't over-tighten and as mentioned, don't overthink it. Millions have been done leak free.

 

ditch that POS and go with an aluminum one

https://www.oreillyauto.com/detail/...l-air?q=Thermostat+Housing/Water+Outlet&pos=0

 

With RTV, the amount that oozes out the outside goes to the inside. And will wind up in the intake, oil pump, oil pump screen, water pump, fuel pump, carb, or any other place you use it. Stick with Perma-tex.

 

Couple of things, as squirrel suggests loose that housing. I have been thru two of them, both developed pin ho;e leaks in the center of the housing. If you do user RTV or some other type of sealant, make sure it is totally dry, and use a heat gun if necessary. Assemble the unit and let it dry over night. It should seal, but use the housing that 36 suggests.

 

OK...... consensus is lose the chrome housing and go with this one that fortunately was sitting on a shelf.
So....... gasket, gasket and RTV, or RTV? lol

 

If it were me I'd true up the mating surface, as suggested, spread a very thin coat of RTV on the mating surface (just enough to hold the gasket in place), install the gasket and bolt it down. Don't overtighten.

 

RTV has uses on an engine, sealing gaskets is not one of them.

 

FWIW,
I used this on the paper gaskets on the backing plates when I replaced the rearend bearings and seals on my coupe
Chappy

20180929_201918 by Chappy444 posted Sep 29, 2018 at 8:19 PM

 

You're on the right track. Now get a piece of 180 sand paper, put it on a level surface (a piece of glass is ideal), and true the mating surface up some. Then getcha some of this:


Done.

 

Gasket with Permatex Form-A-Gasket brushed on each side.......keep it simple

 

my favorite

 

Use Summit gasket Sum-G2399 with no sealer.

 

^^^^ Mine too.... Only caution is don't use it everywhere. Great for thermostat housings, water pumps, oil pans, fuel pumps, OD of press-in seals, other smaller parts. Use it on valve covers and you may bend them if you ever need to remove them. Absolutely don't use this on most intakes for the same reason. The best stuff in the world for painting onto assembled battery terminals to prevent corrosion as long as everything is spotlessly clean.

If you want a RTV-like sealer, try Yamabond (available from any Yamaha dealer). This stuff 'flows' onto adjoining surfaces so it doesn't leave any 'strings' like RTV does. Seals matching machined/flat surfaces without a gasket. Disadvantage is it isn't 'heavy bodied' so it won't fill large gaps (like intake end seals) but works great where you can use it. Other downside is it definitely has a shelf life...

 

for intakes, i like this on the end gaskets on small block mopars. this is the only stuff i've used that never lets those PIA things walk

 

Right, the gasket IS the seal. Can also use gasket maker in lieu of a gasket.

 

I’ve always liked Permatex #2 for thermostat sealing.
Used with the gasket it works great.
https://www.amazon.ca/Permatex-80011-Form-Gasket-Sealant/dp/B000HBM6NG

 

Gasket maker doesn't need a gasket, which is the point init?

 

Those chrome housings almost always get warped a tiny bit in the chroming process and will almost always leak. As mentioned by others, do your self a favor and trash it.

 

I have never got those chrome housings to be leak free unless they have an O-ring.

 

In replaceing a thermostat on a Pontiac Fiero it came with a gasket and it leaked because the factory stamped a number on the machined surface of the head the factory used RTV.