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Old 02-03-2021, 09:50 PM
71 T/A 71 T/A is offline
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Default Thermostat Housing Gasket - Which Sealer?

Do you all like using Permatex Ultra Blue, Black, Red or some other type sealant?
Have to buy some and was curious as to what you think is best.

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Old 02-03-2021, 10:25 PM
tom s tom s is offline
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I use Hylomar on the intake side.Tom

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Old 02-03-2021, 10:30 PM
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Permatex form a gasket.

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Old 02-03-2021, 10:30 PM
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Quote:
Originally Posted by 71 T/A View Post
Do you all like using Permatex Ultra Blue, Black, Red or some other type sealant? Have to buy some and was curious as to what you think is best.
NOT RTV SILICONE.

RTV Silicone is for REPLACING a gasket, (used instead of a gasket) not for application onto a gasket.

There's a dozen perfectly-good gasket sealers, including but not limited to Gasgacinch, High Tack, Copper Coat, Indian Head, Permatex #1, #2, and #3. Hylomar is top-shelf, but very expensive.

"Best"? I don't know. I don't really care. Any of the ones I've listed--and others as well--are entirely adequate. When it's my money, I lean toward Gasgacinch. In the applications that I've actually used 'em on, Gasgacinch does everything Hylomar does, at 1/10 the price. There may be other applications where Hylomar is required--aerospace, for example.

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Old 02-03-2021, 10:49 PM
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I changed to Hylomar because of the clean up.I found it to be non hardening and WAY more EZ to clean than any other I have used.FWIW,Tom

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Old 02-04-2021, 04:15 AM
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For ruff surfaces Permatex #3 Aviation works fine.
If the housing is bent you may need a new housing or make it flat.

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Old 02-04-2021, 08:48 AM
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Funny story: I was 16, and did some sort of cooling system repair that weekend. 1982 Monday winter morning; driving my 1968 LeMans to High school, and boom antifreeze steam erupts while 1/2 mile from the school.

Rather exciting for me to see the steam cloud. Upper hose blew off the Radiator inlet. Well lesson here: never apply RTV to radiator hose joints.

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Old 02-04-2021, 12:10 PM
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Quote:
Originally Posted by Jim Moshier View Post
Permatex form a gasket.
Ditto. I use the #2 here.

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Old 02-04-2021, 02:02 PM
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Never had a problem using permatex ultra black as a gasket dressing....and mostly what I have handy

https://cdn3.evostore.io/documents/f...82180_spec.pdf

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Old 02-04-2021, 03:38 PM
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Before you do anything .... lap the bottom of the housing on something very flat. Same with the intake side if you have a block of metal or something to use.

Most used housings have a bend at the bolt hole ears from years of over tightening. Some new ones have less than perfect machining. And I've seen some OEM intakes with pretty rough machining on the gasket surface.

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Old 02-04-2021, 03:59 PM
Mike Fowke Mike Fowke is offline
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I just replaced the thermostat gasket with Permatex Water Pump & Thermostat RTV Silicone Gasket Maker. The surfaces are a little rough, and the regular gasket was leaking into the bolt holes. Seems to have done the trick.

https://www.permatex.com/products/ga.../?locale=en_us

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Old 02-04-2021, 05:02 PM
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Ah! The old leakin at the bolt hole trick. m
sounds like the Housing has a hairline fracture at the Bolt tab. I had 1 leak through the fracture.

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Old 02-04-2021, 06:10 PM
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Quote:
Originally Posted by tom s View Post
I changed to Hylomar because of the clean up.I found it to be non hardening and WAY more EZ to clean than any other I have used.
Give Gasgacinch a try. I bet you'll like it. And, as I said--very inexpensive compared to Hylomar.

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Old 02-04-2021, 08:54 PM
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My 78 came from the factory no gasket silicone sealer.

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Old 02-05-2021, 02:07 AM
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Quote:
Originally Posted by Schurkey View Post
Give Gasgacinch a try. I bet you'll like it. And, as I said--very inexpensive compared to Hylomar.
They always used that and kept it in the storeroom when I worked on the Bus transportation side of the transit system here. As far as I know, it's still the go-to gasket sealer. No one EVER called that stuff by it's name...it was called 'Pretty Girl'.


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Old 02-05-2021, 06:16 AM
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Quote:
Originally Posted by mchell View Post
Never had a problem using permatex ultra black as a gasket dressing....and mostly what I have handy

https://cdn3.evostore.io/documents/f...82180_spec.pdf
Ultra Black for me too. I put a very thin coat on both sides of water pump gaskets, etc. Thin coat on one side if it's a valve cover or something that is likely to be removed. Never put anything on hose connections. Never even occurred to me. Kinda like people that I've seen put Teflon tape on flare fitting.

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Old 02-05-2021, 10:28 AM
78w72 78w72 is offline
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Quote:
Originally Posted by mchell View Post
Never had a problem using permatex ultra black as a gasket dressing....and mostly what I have handy

https://cdn3.evostore.io/documents/f...82180_spec.pdf
x3 on the ultra black, or ultra grey. ive used it on a few motors in the last 10 years or so & it works great & lasts a long time. i use it as a dressing on timing covers, valve covers, valley pans, etc. my machine shop also used it on my milodon oil pan that comes with the older style crappy 3 prong rubber "U" seal in the rear that would not seal after 2 tries. talked with mr P body & he suggested using the 1/4" cork gasket in that location & a liberal coat of ultra black... been holding great after 6 years & lots of street miles, drag strip runs & some dyno pulls. all other gaskets on 3 of my cars are leak free after 8-10 years too.

all the other products mentioned will work too but to claim (modern) RTV shouldnt be used on gaskets is not correct... as posted above, permatex says ultra black/grey can be used as a gasket dresser, meaning a light thin coat on both sides, especially for pitted surfaces.

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Old 02-05-2021, 10:38 AM
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Permatex Water Pump & Thermostat RTV Silicone Gasket Maker - works well

https://www.permatex.com/products/ga.../?locale=en_us

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Old 02-05-2021, 11:21 AM
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older style crappy 3 prong rubber "U" seal in the rear that would not seal after 2 tries. talked with mr P body & he suggested using the 1/4" cork gasket in that location & a liberal coat of ultra black
I drew the same conclusion on my own. Had those junk rubber rear pan seals split and leak. Use cork seal and Ultra Black and it will never leak a drop.

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Old 02-05-2021, 12:16 PM
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Quote:
Originally Posted by Skip Fix View Post
My 78 came from the factory no gasket silicone sealer.
LOL, I don't remember how my 77 came, from factory....maybe the non Eagle cars got no thermostat gaskets...

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