Using red RTV gasket maker instead of a real gasket when replacing thermostat?

Status
Not open for further replies.
Joined
Nov 11, 2018
Messages
89
Location
Canada eh
Hi all,

I have some left over Permatex High-Temp Red RTV Silicone gasket maker when I replacing the rear diff cover few years back. Now I'm going to replac the thermostat and just want to know if I can use this stuff as a gasket for the housing. On the package and the website it's "recommended for thermostat housings" but I just wanna double check to make sure. The vehicle is a 95 Chevy k1500 with the 5.7 v8



Here's the link:
https://www.permatex.com/products/g...matex-high-temp-red-rtv-silicone-gasket/
 
Last edited:
Not a problem. Make sure your bead size is what they spec and follow the directions. Make sure the surfaces are totally clean.
smile.gif
 
Last edited:
Clean both parts so that there is no oil. Put your goo on and finger tighten the bolts. Let it sit a few hours then final tighten them and add your coolant.

Works well. Many new cars dont use a gasket for things like this. Just goo as you described.
 
Originally Posted by Kestas
I prefer to make my own thermostat housing gaskets.

Thats pretty cool! Share how you do it!
 
I've made thermostat housing gaskets out of the cardboard box the thermostat came in. You cut the box a bit larger than the housing. Take a small ball peen hammer and lightly tap out the cardboard while holding it to the housing. This gives you the perfect outline to trim by.
 
It's rather easy. Trace the thermostat housing on gasket material and cut. Gasket material doesn't have to be anything fancy. You can use thick paper material sometimes used in packaging or even milk carton material.

Beats running down to the store and paying 50 cents.
 
You could use the cardboard box to make the gasket, and then keep some Indian Head shellac on hand to waterproof the paper before using it as a gasket.
 
It'll work - as long as the silicone is still dispensable and it "kicks". No Dex-Cool or "all makes all models" coolant of course...
 
I did make a gasket for an integrated thermostat housing (plastic so) bolting on aluminium engine. Using red silicone. I tightened right after applying and filled the circuit 2 hours later and went for a drive. It's been 7 months and 7000 miles and no leak so far!
 
If a gasket is available I'd buy one and use it, if not I'd make one. The RTV gasket maker I'd use a last resort. Opinions vary.
 
Originally Posted by Kestas
It's rather easy. Trace the thermostat housing on gasket material and cut. Gasket material doesn't have to be anything fancy. You can use thick paper material sometimes used in packaging or even milk carton material.

Beats running down to the store and paying 50 cents.


What material do you use?

And yes, you bring a really good point.
 
Use both, just a smear of red or black. Used red on my 95 GMC two years ago and no problem. On intake manifolds where gaskets can squirm out of place I use RTV on the manifold side and let it setup for 20 minutes before setting in place.
 
Originally Posted by das_peikko
Use the Ultra Black instead. Butter both mating surfaces. Wipe off the squeeze-out. Give it a full 24 hour cure.

Good way to clog water passages.

RTV should only be used when specifically called for by the repair procedure, and it should be used sparingly.

Hacks glob it on and call it "good enough."
 
Don't use RTV. It seals better than gaskets, but the risk of little pieces breaking off and clogging passages is much higher. Everyone thinks they can apply RTV perfectly...but they can't.
 
You have an actual flat gasket that is solely for the thermostat housing? None of my cars do, all of them have a round rubber gasket that fits onto the thermostat and seals both the housing and the thermostat against the head. In that type of application you wouldn't ever use RTV.
 
Status
Not open for further replies.
Back
Top