Small Block Chevrolet Thermostat Housing

[c3po]

I got a new thermostat housing since I no longer go through emmisions, the new housing has a o-ring, should I still use a gasket. The place I got from said try it without, whereas another guy with the same thermostat housing said put the gasket on. I am leaning towards putting the gasket on.
The gasket is a GM part that is some sort of synthetic material that you put the gasket on dry, this guy who has it on his car, not sure what gasket he has, says to put a bead of silicone on both sides of the gasket.
Tell me if I am correct:
1) Put the gasket on
2) Put it on dry with no RTV Silicone
The manifold is an Edelbrock aluminum 2101, any help would be greatly appreciated as I plan on doing this tommorow.

 

[87sammy]

I would use the gasket with silicone on both sides.

 

[c3po]

If I put silicone on both sides does this mean :
1) If I change the thermostat I have to get another gasket
2) I have to let the silicone dry or cure for 24 hours.

 

[Saturn_Fan]

Originally Posted By: c3po
If I put silicone on both sides does this mean :
1) If I change the thermostat I have to get another gasket
2) I have to let the silicone dry or cure for 24 hours.


On my thermostat housing I used the OE gasket along with some of the permatex high temp RTV (it was orange) and let it cure for 24 hours. Never had a leak or a problem for the past 40K.

 

[Shannow]

If it's an axial O ring, it's indefatigable, radial O ring, wouldn't give you two bob for it.

Axial O-ring, set and forget.

 

[mechtech2]

The mating surfaces must be clean and corrosion free.
If so, then you can use the 'O' ring type. At this point, take the extra 20 seconds and smear some silicone RTV all over the 'O' ring, then assemble it. Dry time? For this, an hour or two before filling the coolant is OK.

 

[Saturn_Fan]

Originally Posted By: mechtech2
The mating surfaces must be clean and corrosion free.
If so, then you can use the 'O' ring type. At this point, take the extra 20 seconds and smear some silicone RTV all over the 'O' ring, then assemble it. Dry time? For this, an hour or two before filling the coolant is OK.


The RTV tube I used said to cure for 24 hours for best results, before exposing to heat, IIRC.

 

[c3po]

I did exactly what mechtech2 said, I called up the Mr. Gasket tech line and they recommended the RTV and said not to use a gasket. My tube of RTV said the cure time is 24 hours at 70 degrees, so since it is a little bit cooler than that at night I will let it cure 48 hours.

 

[Chris142]

Those chrome housings with the O-Ring never seal.

 

[c3po]

If that is the case then I will have to get an aluminum 1 if this 1 does not work.

 

[mechtech2]

I have used cases of RTV in various applications.
Yes, full cure is 24 hours, and is of course better if you have the time. Longer is better, especially with valve cover gaskets and differentials.
For a simple thermostat gasket, 1-2 hours has proved sufficient.
Let it set up before assembly 10 minutes first [exposed to air].

 

[c3po]

By the time I drive the car tommorow to test it out the car would have sat for 50 hours, I think this is more than sufficient, I could take it out tommorow, but I want to drive it after I get home from work, thanks Mechtech2.

 

[c3po]

I took the car out this afternoon for a 10 minute drive and no leaks, I will be going out tonite and report back. I am not going to JB Weld the crack in my old thermostat housing. This chrome housing with the O-Ring seems a lot more beefier in construction than my old 1, also that old thermostat housing was on there for 25 years, time to retire it.