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Which gaskets do you use sealant on for the engine? What type of sealant is best?

I'm particularly looking for an answer on the intake manifold gaskets as I'm about to put mine back on. I put the throttle body on without any sealant on the gaskets. Is that OK or should I take it back on and put sealant on?

I usually use a light film of permatex just for good measure and to hold the gasket in place while positioning,but dont take stuff apart to do it,its fine without.

I typically put the gaskets on dry. They've worked fine and don't leak. I've had the TB gasket on an off several times and still no leaks.

If you look at the stock subaru gaskets, one side will feel like it has an adhesive on it. When that heats up, the gasket will stick to that side of the part it's on.

Some of the Subaru gaskets are an adhesive type, and some are not. All the pinkish colored gaskets seem to be of that type, like transmission gaskets. I don't think the carbon gaskets have the adhesive though. I could be wrong.


I like to use the Permatex Copper Gasket Spray in certain places. I used it on my Cometic head gaskets. Ron at RAW Performance recommends it for his shortblocks.

I want to put it on the intake manifold gaskets for good measure and because they got a couple creases on them from taking the manifold off and putting it back on like 3 times but I'm just worried I might have to take it off again for something and then I'll need 4 new gaskets because of the phenolic spacers. Also, I don't know if those spacers will hold up to scraping with a gasket scraper.

If you think you might be removing the intake manifold again, I wouldn't use the sealant.

The only gasket I have used sealant on was a DOHC valve cover......just to make sure it wouldn't leak....since it's a bitch to replace.

I don't see why I would but then again when I first put it on I didn't think I would then either and I did a couple times after that.

Check this POSTon the USMB....useful info about seals, sealants and gaskets.

GL,
Td

Thanks again wtdash! This is quite interesting.

3. Intake manifold gaskets - The OEM gaskets are designed to go on dry. Using RTV sealant in place of the gaskets or in addition to them WILL cause a water leak into the intake as well as externally. If you feel that you must put something on the intake gaskets, or if you are stuck using aftermarket ones, put on a light coating of copper spray-on sealant.

I wonder why?

Silicone most likely doesn't bond to carbon gaskets that well.

Where is the water leak coming from? There's no water at the intake manifold mounting surface.

When you drive in the rain, there is water everywhere.

You should be able to hose the engine down with water and it will run fine. If not, you have issues.

That's what I was thinking he must mean.

kimokalihi wrote:Where is the water leak coming from? There's no water at the intake manifold mounting surface.

On the earlier EA series motors, which covers a lot of USMB posters, there is coolant in the manifold.