RTV vs. gasket sealant

[JHZR2]

Hi,

Doing a valve cover gasket job hopefully real quick, and noticed that the manual said to use sealant with the (rubber) gasket in a few spots.

Looking online, most of the time people seem to indicate use of RTV for this.

I have a tube of Permatex super high-tack gasket sealant (97B).

Is one better than the other? Seems that the naming of mine means that it is ideal, but again, so many seem to advocate use of RTV.

Suggestions?

Thanks!

 

[mechtech2]

Silicone RTV IS a gasket sealant.

On valve covers, many factories use a bit of RTV at the corners, or half moon seals .
RTV is great for this. Get a good automotive one. Clean off the oil and let it cure before starting.
How long? Temperature is a factor. If the car is winter cold, as long as possible, up to a day. In summer I still like a few hours.

 

[JHZR2]

but what if I have 97B in my shop? good enough? the same?

 

[Oil Changer]

Your 97B is an excellent choice. Even better since it is already paid for and at hand.

Permatex makes a dedicated product, but I wouldn't waste the time/money since you have something that will work.

http://www.permatex.com/products/Automot...nt_Dressing.htm

 

[The_Eric]

Use RTV. High Tack seems to work better with paper type or close fit applications.

 

[morris]

i had a friend that worked for fel-pro. they would NOT warranty a valve cover gasket if rtv was used on it. they recommended a product like " Permatex super high-tack gasket sealant (97B)." i have used permatex #2 for decades it all ways works.

 

[The_Eric]

Originally Posted By: morris
i had a friend that worked for fel-pro. they would NOT warranty a valve cover gasket if rtv was used on it. they recommended a product like " Permatex super high-tack gasket sealant (97B)." i have used permatex #2 for decades it all ways works.


In some cases, they specify you use it, in fact they even supply it with certain kits.

 

[JHZR2]

I did the job with the gasket sealant.

I put some on the half-moon area on the head, it was freezing cold (literally) out, figured Id need to give some time for it to tack up - it turned tacky, and then started becoming non-tacky much sooner than I had planned. Hope I didnt screw that up...

 

[JHZR2]

Started the car today. Not sure if it was me, the cold, or something else, but it seems that I got 50 rpm of idle speed.

My idle was about 50 RPM low. After cleaning the IACV and its connections, etc., all idle issues stopped but it still looked a tiny bit low. Time will tell if that was the case.

The idle was always very smooth, but sometimes sensitive to load changes. These engines are sensitive to vacuum, pull the oil filler cap or dipstick and the engine will stall...

Since I used gasket sealant and not RTV, and since it wasnt as tacky as Id had liked, anything I should keep an eye out for, besides the usual oil leaking out, that would be indicative of an issue?

 

[JHZR2]

No dice - idle still at 650ish. Rock solid and smooth, so guess nothing changed...

 

[cchase]

Gasket sealant IS RTV... RTV stands for "room temperature vulcanization".

 

[JHZR2]

OK, that helps... But then why does permatex sell 97B, versus all its RTV variants?

I can certainly understand varieties for certain applications, like gear oil, where the material needs to stand up. But to have RTV, AND all these other things too? Seems like so many redundant items, each must have its best use...

 

[mechanicx]

Gasket sealant is RTV but is best for holding a gasket in place and helping it seal as its namesake is. It is not suitable to take the place of gasket maker RTV where you use it in place of gasket or to seal the area between two gaskets. I think that's the main thing. You can get away with using gasket maker on a gasket if spread thin and evenly but you can't use gasket sealer in lieu of a gasket. Of the two usually it's best to use the sealer on a gasket like you did.

 

[morris]

which cases? i started working on cars in 1965, be fore we even had RTV. i have only use permatex #2, it has NEVER failed me. end of story.

 

[JHZR2]

Originally Posted By: mechanicx
Gasket sealant is RTV but is best for holding a gasket in place and helping it seal as its namesake is. It is not suitable to take the place of gasket maker RTV where you use it in place of gasket or to seal the area between two gaskets. I think that's the main thing. You can get away with using gasket maker on a gasket if spread thin and evenly but you can't use gasket sealer in lieu of a gasket. Of the two usually it's best to use the sealer on a gasket like you did.


Great stuff, thanks!

The only spot where it is required is the half-moon seals that are part of the VC gasket in the back. That is where I used it, as well as around the bolt holes, as there was evidence of something having been used there on the old gasket.

the half moon is not two gaskets, just a spot where a big chunk of rubber fills a metal void.

Sounds like my product was the right choice. Hopefully my technique was OK.

Thanks again.

 

[mechtech2]

Permatex #2 is great, but not with rubber type gaskets.
[They were kinda rare years ago].
Silicone RTV is the new King.

 

[JHZR2]

Permatex #2 is not what I used. I used high tack gasket sealer. #2 is Form-A-Gasket Sealant.

Or are they really the same?

 

[SZR48207]

Apologies for resurrecting this VERY old thread, but it asks the exact question I have in mind.

If Permatex Form-a-Gasket Sealant #2 is not RTV, then what is it?


I have both Permatex black RTV and the #2. I know that the RTV can be used to make gaskets if I can't just buy a factory cut gasket.

I don't think the #2 can be used to make a gasket as it has a much different texture/composition. It almost smells like Shellac.


Is #2 a "historical" product from a time when gaskets needed to be given a coating in order to work properly? I have used bare modern paper type gaskets for a very long time and haven't had leaks.

 

[das_peikko]

Originally Posted By: Reddy45
If Permatex Form-a-Gasket Sealant #2 is not RTV, then what is it?


Whatever it is, it can only be broken down with hydraulic brake fluid. It's very effective in treating cork and paper gaskets making them oil and waterproof. Gasoline takes a long time to break it down.

 

[Lubener]

Originally Posted By: JHZR2
Hi,

Doing a valve cover gasket job hopefully real quick, and noticed that the manual said to use sealant with the (rubber) gasket in a few spots.

Looking online, most of the time people seem to indicate use of RTV for this.

I have a tube of Permatex super high-tack gasket sealant (97B).

Is one better than the other? Seems that the naming of mine means that it is ideal, but again, so many seem to advocate use of RTV.

Suggestions?

Thanks!

Don't pay attention to what the manual states, ask someone from the gasket maker if they suggest a sealant to be applied to their gasket.Personally, I would never use RTV on the surface of any gasket,only the joints.Rubber should have nothing on them, cork or paper, I use permatex 2.