Changing Thermostat and using Sealer? - Ford Mustang Forum

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post #1 of 6 (permalink) Old 10-12-2012 Thread Starter
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Changing Thermostat and using Sealer?

So im going to be changing my 1988 302 thermostat and i noticed in a few videos on youtube of people replacing it. They use some sort of sealer on the housing that they put the gasket over once they've replaced and are ready to put everything back together. They use some sort of silicone? or rtv sealer?

So before i replace my thermostat, can anyone recommend the proper sealer i should use to seal this thing right please.

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post #2 of 6 (permalink) Old 10-12-2012
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permatex ultrablack rtv or "the right stuff". you dont even need a gasket with either of the two

1987 Notchback - N/A stock 302, TFS heads, Holley Systemax, FTI cam, Astro A5
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post #3 of 6 (permalink) Old 10-12-2012
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I didn't use any sealant, just the gasket. Made sure all surfaces were nice and clean first. Spray of gasket remover and a razor blade.

img 2
No leaks.

Anyways to actually answer your question, like need4spd said, Permatex ultra black RTV.
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post #4 of 6 (permalink) Old 10-12-2012
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Personally, I like to use the Permatex high heat RTV (The red stuff) buts thats just personal preference.

Also, specifically on the thermostat housing make sure its SUPER clean. This is a spot that loves to leak if you don't clean it up perfect.

1991 GT: Trick Flow Track Heat Heads, Trick Flow Stage 1 cam, Ported GT40 Intake, 1.6 Rockers, 24 lb. injectors, 190 LPH Fuel Pump, BBK 70mm TB, BBK Headers, Off-road H, Flowmasters, 3.73's, Eibach Springs, Hotchkis Control Arms, FRPP Alumuinum D/S

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post #5 of 6 (permalink) Old 10-12-2012
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If you use one don't use the other. It always works best with either just the gasket or just the rtv.

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post #6 of 6 (permalink) Old 10-12-2012
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Iv found what works the best is to yes clean the surface very well where the gasket lays. Be careful not to ruin the surface with sandpaper, razor blade, etc..very easy to make the surface uneven. If you look closly there are little levels where the thermo and gasket lay perfectly. Next take the smalliest amout possible of the gasket maker and put it on the lower intake where the gasket would lay. You only want to use it for the gasket to stick in place. You just want it sticky not globbed on or even a layer. Just sticky enough for the gasket to stay. If anything put three pin size dots of the goo. thats all you need. Then continue the rest of the procedure like you would normally. If its going to be cold where you live i would suggest not putting a 180 thermo in for the winter. Your car will never get up to running temp and winter. not good!!!! A lot of people make that mistake. The thermostat is a very cheap part like spak plugs but is very important to your motor like plugs!!!

98 merc mountaineer short block, E7 heads, b cam, 19lb. EV6 injectors, 75mm tb, 75mm EGR delete spacer, stock maf, screamin demon coil, ford racing 8.8mm. plug wires, autolite #25's, 3.73 rear, refurbed t-5 trans, steeda tri-ax shifter, stage 2 clutch kit, lakewood drag suspension, sve upper and lower control arms, v6 contour fan, bbk shorty headers, bbk catless x-pipe, flowmaster 40s to dumps, 3G 130 alt, welded and bolted subframe connectors
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