still cruzin

I know this has probably been hashed around a few times already!

I have a very small leak from my thermostat housing on my 67 350hp. I'm looking for the best gasket sealer? Has anyone used the permatex thermostat RTV silicone with good results?

Use it WITH a paper gasket? Or Without? Whats the best procedure?

I know it's best to just snug and not tighten to much. But do you apply and wait for it to set up a bit and then tighten, or tighten quickly?

I've always had good luck with just a paper gasket and a little adhesive, but this time its not working!

Bob

sixtysixtom

I use permatex super black on both sides of a fel-pro gasket. Never leaks. Let it set up for 24 hrs before you run the engine
66tom

Nowhere Man

I had a problem like that I had to get the manifold planned down on the housing oping along with the housing it self before it stopped. but a good RTV and a paper gasket should do the trick

Plasticman

Permatex makes a special RTV for thermostat housings, and it works. It is marked "Water Pump & Thermostat Housing RTV Silicone Gasket", and comes in a small (.5 oz) grey tube.

http://www.permatex.com/products/Aut...one_Gasket.htm

"Regular" RTV always seem to eventually leak, when used around coolant.

Plasticman

mikem350

The problem is not in the sealer, its that either surface is not completely flat...

Take the therm housing and rub it across a piece of 100 sandpaper (on a flat surface). Go back and forth like an X, and rotate around every 10 strokes. You will see a pattern where its not flat. Keep going till it all even.

Use a thin coat of ANY sealer you have, both sides of gasket, let dry b4 adding coolant. DONT overtighten!

Also if you ever use chrome plated parts...guaranteed they will leak

MikeM

Now you're talking about the real problem.

still cruzin

No Chrome here! All factory parts. I did the sandpaper trick before I installed it the first time, so I know everything is "flat" I'll try again and see what happens.
Thanks for the helpful comments!

Bob

MikeM

Okay, if everything is flat then take a sharp tool and run around the groove your thermostat sets in. Sometime crud build up in there and hold the thermostat up and cause a leak at the gasket.

Bear in mind, the factory used no sealer nor did they need any.

PS. If your attachment bolts aren't going into blind holes, use sealer on them to keep them from weeping coolant up the threads.

JohnZ

If the surfaces are flat, you don't need any sealers. GM has a great paper gasket with a silicone bead molded on both sides that's invisible and seals perfectly - #10105135.

midyearvette

if you feel you do need to use a sealer then this is the only stuff to use that works with antifreez

still cruzin

Thanks again!

65GGvert

That's the one that finally stopped my leak. I tried the Permatex water pump/thermo seal, but still got some seepage after heat up. The gasket above stopped it.

65ZR1

I have an original 2x4 manifold and thermostat housing. All I use is a thin coat of " The Right Stuff" ( cant remember who makes it) on the thermostat housing. No gasket. Simply put it on, assemble and tighten up the bolts. By the time Im done putting in the coolant it is dry and good to go. I have never had a single leak.

Tampa Jerry

If you are using an aluminum housing, check for any small cracks in the housing. My BB Chevelle had a very small leak and I tried all of the above to no avail. I changed out the housing and the leak stopped. I think that by torquing the housing bolts down, the crack became more pronounced. Jerry

Bill32

The Right Stuff is made by Permatex.

I've been using it a long time, I've thrown almost all the RTV I have.

TRS is what you see on new car oil pans, waterpunps,etc. where there are no gaskets being used.

I use it at the track on the transaxles when changing gear ratios, put it on the cover, tighten it up and drive immediately with no leaks, RTV will leak every time.

There's no waiting to skin up, no retorque like you do with RTV.

It doesn't leak at all on the china walls when you do your intakes.

It comes in a aerosol can but, if you can find it, it also comes in a tube to use with a regular caulk gun (works much better).

TRS just blows away RTV.

6T5RUSH

What JohnZ posted up is what I'm using. Purchased from Autozone for $8.00. No goop...no leaks. Here's a link:

http://www.autozone.com/autozone/par.../N-ixfelZ9pdkd



Jim
In God We Trust!

JohnZ

That's the thick blue plastic Fel-Pro gasket, which works fine, but it's highly visible when installed; the GM gasket I posted above is about 1/3 the cost, seals just as well, and isn't visible.

Plasticman

The Fel-Pro gasket has come down in price considerably. At one time, it was a $20 item! Now it is $7.99 (online quote from Advance Auto using FL zip code).

http://www.autozone.com/autozone/par...er=157141_0_0_

Plasticman

Redbird

On my 62s I use the over the counter gasket from O'Reilly's. Clean both surfaces and thread sealer on the bolts. Torque down & No leaks.