The Stovebolt Site Forums The Shop Area Engine Shop Looking for some general gasket guidelines

I would appreciate someone giving me some guidlines on gaskets. I'm replacing a few of them on my 235 and I'm still not sure how to decide whether or not to use gasket sealer. I have the service manual, but of course products have changed, and there are a myriad of things to choose from. Other threads in this forum talk about specific sealers or gaskets, but I guess I'd like to get some schoolin' on a more general level. For example, would you always use a sealer on cork gaskets? If so, do you always put it on both sides? Does your decision matter if the joint being sealed is subjected to pressure? Does it matter if the fluid being sealed is oil-based (engine oil) or water based (coolant)?

I know I'm probably thinking about things too much, but I'm trying to understand the thought process so I can make good decisions in the future, rather than asking a question for each and every situation I encounter, or relying 100% on guidance from a manual that is 50+ years old.

Right now I have a tube of Permatex RTV 26B (red), and I'm scratching my head... should I put it on my pushrod cover? Doesn't seem like it should be necessary. What about the timing cover gasket? Maybe, as it seems like that area would be under more pressure. And the oil pan? Hmm..

In cases where sealer is "optional", it seems like you gain the ability to stick the gasket for ease of installation at the price of having to scrape the mating surfaces clean if you have to remove it in the future.

Some engineer (or marketing person) decided that there was a specific need for a huge range of products: Example 1 Example 2, so perhaps I need to start reading up!

Somebody bring me in to the light!!

I personaly use as little gasket sealer as possible. If the surfaces to be sealed are clean and flat the gasket should seal it. On oil pan gaskets I use a dab of number 2 Permatex where the gaskets meet. Most of the old water pumps and thermostat housings that I work with are badly corroded and I use permatex on those also. I dont enjoy scraping gaskets off.
Cleon

I always use the old sealer that has been out for years called "Indian Head" I think. Has always sealed well for me and never had a leak. Comes in a bottle with a dauber.

Permatex #2 and perhaps High-Tack (or Indian Head, similar product), and Permatex Aviation Sealer, is all you need for these old trucks. They were recommended back when they were new, and really, nothing else that's come out is really any better. Don't use the RTV on the gaskets, though. That stuff is intended to replace gaskets, not be a sealer for them. Most cases, using it on a gasket will make it leak worse. Not saying RTV doesn't have its place, but used a s a gasket sealer is not one of them.

I gotta look next time I go into town, I haven't seen Indian Head gasket shellac for many many years. I used to be a staple around any garage for sticking a gasket to one side of something like a rocker or side cover.
Denny Graham
Sandwich, IL

I thought I saw it at Danville Auto Parts (my favorite flaps), I''m going there tomorrow to pick up a bearing for a pully removal tool, I'll check to see if it's still available.

Bill-

So it looks like the Aviation sealer is basically the same as #2. When would you use one over the other? Is the Aviation sealer basically "better" (and probably more expensive) #2?

I also gather that the "High Tack" would then be your general all-purpose gasket sealer that is used everywhere except for non critical places that have a high chance of being dissassembled in the future (valve cover, oil pan, pushrod cover).

Does that sound about right?

If it basically boils down to two products then I think I can live with that.

High-Tack and Aviation Sealer are similar, with Aviation Sealer being slightly thinner in viscocity, but stayin tackier longer. I like High-Tack on stuff like rocker covers and lifter covers, Aviation Sealer works nice on thin gaskets, like trans gaskets and thermostat housings. Seems that #2 si suggested more for threads in the manuals, Ifind that Fel-Pros Plia-Seal works about the same in that application. I do prefer Permatx High Temp Thread Sealent for plugs that go into coolant, though. As far as pricing, Aviation Sealer and High Tack are about the same, maybe a few cents one way or the other.

"Aviation Sealer" is a brush-on liquid that's sort of a poop-brown color, and it has very little "sticky" properties. High Tack is more of a glue than a sealer, designed to stick a gasket into place while the part is being positioned. I prefer a variation of aviation sealer called Permatex Super 300, which is almost black, and seals much better than 3-D, which is the regular aviation brush-on sealer. Super 300 was developed to seal aircraft fuel system parts exposed to 115/145 octane aviation gasoline, and it's remarkable stuff! I use it on steel shim head gaskets on race engines, not to seal compression, but to prevent hot coolant from seeping into places it doesn't belong. At oil pan corners where side gaskets meet front and rear pan seals, I like to use a dab of RTV to bridge the joint and prevent oil seeps. Ditto on small block V-8 intake manifold corners.
Jerry