Sealants and Gaskets 101

[spectre6000]

I'm the sort of guy that studies up on something before I mess with it. All theory, no experience. Usually that gets me exactly where I want to go, but sometimes there is a little more to it. Said another way, I can build a VW engine in my sleep... in THEORY. What I've discovered is sorely lacking in what I've read is just about any mention of sealants. Everything I read says something to the effect of "put a gasket there and bolt it up." The oil in my engine compartment begs to differ. Apparently there is supposed to be RTV on the gaskets for the generator stand and the fuel pump or something? Also o-rings, pipe sealant, indian head, loctite.... What are all these? What do they do exactly? What are their limitations and their strong suits? When are they used? Also, gasket kits often come with different types of paper (thick, thin and thinner), metal sandwich things with some sort of metallic composite, metallic composite, o-rings, etc. What are the differences between these? Uses, strengths, weaknesses, etc. School me!
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Jason Hopper

-'58 German Market Deluxe Beetle (in progress)
-'84 M1009 CUCV
-'81 K10
"Buy the best, cry once." -Gene Berg
"A cheap man will always buy the cheapest thing available, and then buys another one hoping for a better result, and then spends the rest of his life in misery complaining about it. A thrifty man will buy a good part once and never think about it again." -RockCrusher
"Don't feed the Shitty Parts Monster!" -Me

[mharney]

Forum search on "sealants" will give you some threads with a lot of discussion on this.

[spectre6000]

You would be correct. The reason for starting a thread about it is to get it all in one place in a cohesive and coherent format instead of a bunch of random mentions of "loctite" or "rtv" buried three pages into a thread.
_________________
Jason Hopper

-'58 German Market Deluxe Beetle (in progress)
-'84 M1009 CUCV
-'81 K10
"Buy the best, cry once." -Gene Berg
"A cheap man will always buy the cheapest thing available, and then buys another one hoping for a better result, and then spends the rest of his life in misery complaining about it. A thrifty man will buy a good part once and never think about it again." -RockCrusher
"Don't feed the Shitty Parts Monster!" -Me

[jfats808]

Instant gratification at its best. We cant simply make a sticky for every little detail imo. Doing your own searching on certain topics gets your feet wet and puts hair on your chest.
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2276 IDA's 86C 11-1 DD !
2017 48 Trijet DRLA's W125

[Dale M.]

Sigh....10,000 words already written and one can not find an answer.....

Dale
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All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[MConstable]

Sealants and gaskets are like assholes...everyone has one.
...wait a minute, I told it wrong...
Sealants and gaskets are like assholes, they keep the fluids where they belong
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1974 Thing

[Ian Godfrey]

Spectre
I am like you, lots of study, not many motors so I searched a lot, looking for which builders used what. These are some popular ones I found..... My apologies to anyone misquoted or left out.
I have settled on loctite 515 for dressing and 518 for cases. But a lot depends on the tolerances of the parts and the way you use the products and whether you are tearing down the engine often.

Case halfs
Curil T
Curil K2 “better” Jake Raby
Loctite:
510, High temp 400 degree (the only one) solvent resistant. Good for gasket dressing as well, similar to 574 but rigid. Red colour
515, flexible. Good for gasket dressing as well. Purple colour
518, more popular including Pat Downs. Flexible, special for aluminium. Easy to disassemble and clean up. Acetone is suggested as a cleaner (Use gloves) red colour
574, “Porsche sealant” fast cure, good for large gaps ‘semi rigid’. Orange colour
Permatex 3h ….very popular

“Use good sealants, like Curil K2, Curil T Loctite 518 and 574 as well as Dirko and Yamabond to name just a few” Jake Raby

Manifold to head
Porsche case sealant 574, with no gasket. Suggested by Pat Downs

NPT threads
Loctite:
565 higher strength
567 less strength but more Teflon so there is less galling for stainless/aluminium
Don’t use much, you don’t want Teflon in the oil system.
Loctite red nut lock or blue stud lock (blue is better when there is a bit of oil around) green is probably over kill (often needs heat to break free)

Barrels to case
Loctite: 518/ 515 sealant. Suggested by Mike Lawless
Curil T suggested by LN engineering

Oil pump to case
Silicone but very thin

If any one wants to add to this list or comment, feel free

[spectre6000]

Thank you Ian.

When are these things appropriate/inappropriate to use and how? Does every gasket get some sort of sealant? How do you decide which one? Both sides of the gasket or just one? On the gasket or the parts being sealed? Does every threaded thing get loctite? What about antiseize?
_________________
Jason Hopper

-'58 German Market Deluxe Beetle (in progress)
-'84 M1009 CUCV
-'81 K10
"Buy the best, cry once." -Gene Berg
"A cheap man will always buy the cheapest thing available, and then buys another one hoping for a better result, and then spends the rest of his life in misery complaining about it. A thrifty man will buy a good part once and never think about it again." -RockCrusher
"Don't feed the Shitty Parts Monster!" -Me

[jfats808]

These are one of those " you gotta pay to play" kinda deals. If you built an engine or even took one apart and rebuilt it then you would know what to use and not to use. Thing is you can find all your info about what OTHER people use by using the search function and all of 10 min. Sealants are like oils, lots of choices and lots of preference. Theory means sh-t if you cant apply it in a real world application. Get your feet wet.
_________________
2276 IDA's 86C 11-1 DD !
2017 48 Trijet DRLA's W125

[chrisflstf]

[akokarski]

search is good, but problem that I see in this particular case of question is that it's easy to miss an area that requires sealant. For instance lower cylinder head stud bolts. I don't think any manuals/books mention sealant in this area at all, but these do need to be sealed.

Just saying... I always wished there was a comprehensive sticky on this and different opinions on which sealant to use in which area.

Anton

[mharney]

[modok]

Problem is people don't agree.
Mechanic A says " vw didn't use any gasket sealant when ThEY built it, the engine requires no sealant"
Mechanic B says "silicone sealant can be used with, or in place of, paper gaskets"
Mechanic C says " only sealant you NEED is a nonhardening type sealer at the case halves, studs, and at the other metal to metal contacts that use no gasket"

Who is right? They are all in a way.
In reality mechanic C gets his way. He says "look I'm the boss so just do it like I tell you. And quit standing around, one bomb would get you all"
But he's got his own agenda too, got his reputation to maintain. Use a bunch of silicone people might think it's hack job and he's too cheap to buy a good gasket set. Carefully apply 20 different types of sealer to every little thing and the profit margin goes away.
What would you do?

[ralf]

-non vw use-
i used to use.. threebond (same as hondabond or yamabond) i think it is just repacked per mfg. lol

but i did notice when using them on honda valvecover gaskets (rubber)
after a day of running, prolly even half a day, when it gets heat and it cures, it makes the rubber gasket extremely brittle , tells me they dont like each other (threebond and rubber lol) and silicon hi temp just seems messy ,

til i found this sealant (the name escapes me now..il try to take a pic of it soon) which is also "grey" in color like threebond, but at operating temps and when fully cured, does not get hard like threebond (though threebond when cured isnt solid hard)

tried it on the rubber valve cover gasket (honda head) and the oem rubber seal didnt get hard at all.. plus the sealant isnt cooked so removing them from the rubber seems easier than threebond...

fastforward today.. i use it on the valvecover gaskets of my bug ,
and barrels , hasnt gotten hard after that... no leaks too..

also works great on case halfs, im curious if the permatex aviation one is grey.. this myt be of the same kind?


realized, living where i live... reading suggestions online of sealants, usually the suggestions are based on the availability to them locally.. meaning it aint local to me..

maybe thats what confuses some people, online stickies, and it aint available local to them LOL

HTH (will take a pic soon of the sealant im using)

[Jake Raby]

518 on cases doesn't have great longevity.. Meaning I have found it to start weeping at 50k because it won't flex. I favor K2 for cases.
Everyone has a different opinion. I use 7-9 sealants on my engines because no single sealant works well on all flanges and area of the engine.
What we build doesn't leak, not even with synthetic oil at 80k miles+.

Ask ten people and get ten different answers, I have zero tolerance for leaks of any sort. If it leaks it doesn't leave Aircooled Heaven.
_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

[spectre6000]

How about some generalities? I've never built an engine, but will be doing so in the near future (hence asking the question). I don't want want to throw a few thousand dollars down a hole for the experience of trying various gaskets and sealants. I know loctite is used when you don't want something to vibrate itself loose, but you don't use it if you ever want to get the thing off... You would use a sealant if you don't want something to leak I assume, but I know there's more to it than that. What does one look for in these things? When are they used (generally), what characteristics should be sought (heat ranges are clearly of concern, and apparently so too is pliability over time and potential chemical reactions with nearby materials). I know there are different types of sealants: silicone, Indian Head (I don't even know what this is to be honest, but I was given a partial bottle with a chuckle and a "use this on gaskets" with no explanation which gaskets or why or even what it was). I've got all the manuals and have purchased (and read cover to cover) every VW related book and most magazines carried at Barnes and Noble over the past few years (they change the regularly stocked books every few months or so), and at best there is a mention of using a sealant, but nothing about the sealants themselves. I'm looking for a base level primer on what they are, what they do, the types, the characteristics, dos and don'ts, etc. Specifics names and brands only help if they can be found (or if I know what they're supposed to do). Thanks to those who have chimed in.
_________________
Jason Hopper

-'58 German Market Deluxe Beetle (in progress)
-'84 M1009 CUCV
-'81 K10
"Buy the best, cry once." -Gene Berg
"A cheap man will always buy the cheapest thing available, and then buys another one hoping for a better result, and then spends the rest of his life in misery complaining about it. A thrifty man will buy a good part once and never think about it again." -RockCrusher
"Don't feed the Shitty Parts Monster!" -Me

[andk5591]

I have a book that I believe was put out by Hot Vws or VW Trends that I this is called VW performance engine building or something to that effect. Anyway, there were various builders featured on build ups and I t each one had their own preference for sealers (or lack of) for the various stages of engine builds.

This gets into "there is no right answer" territory. People like Jake, AJ, Art at ACE and on and on have found something that works for them and they stick to it. For me - between Permatex Right Stuff and Aviation sealer I am covered (and not with oil)

If you did a search, you will find a multitude of suggestions and most of them work. And as was said earlier, this has been cover many times and I was surprised that Jake even bothered to chime in, since he and other have answered this before many times.
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There's more, but not keeping them...

[spectre6000]

I don't want to know which ones to use, I want to know what they are and WHEN they are used in general terms. Here are some examples:

The metal sandwich gaskets are used for exhaust manifolds because ______
and carbs manifolds because _____.

The red/blue/cream colored paper gaskets are different because they ______ and are used where _____ and _____ are connected.

Loctite makes things not unscrew from vibrations and should never be used _____.

Silicon sealants do ______ well but suck at ______ and are typically used to _________

Specifics are more or less limited by cost and availability, knowing the general details can help me make my own decisions versus just doing what pick-a-lugnut is using.
_________________
Jason Hopper

-'58 German Market Deluxe Beetle (in progress)
-'84 M1009 CUCV
-'81 K10
"Buy the best, cry once." -Gene Berg
"A cheap man will always buy the cheapest thing available, and then buys another one hoping for a better result, and then spends the rest of his life in misery complaining about it. A thrifty man will buy a good part once and never think about it again." -RockCrusher
"Don't feed the Shitty Parts Monster!" -Me

[modok]

I get ya, but it's hard to know where to start.
I would say there are three main types of sealant
Hardening/adhesive
Non hardening/flange sealant
Silicone/"gasket in a can"

The first type gets hard and glues things together. Locktite is a great example. It permanently adheres to surfaces and gets rock hard. You might throw in epoxy too, but epoxy is not for small gaps.

The second type is mostly sticky goops, like plumbers putty or chewing gum, except for small gaps not kitchen sinks. These are sticky goo that never dry out and fill gaps, but never actually harden. It remains a putty like consistency so as parts move and shift it can move with them.

Silicone is it's own category because it is a little of both, it does cure and adhere to parts, but it is also quite flexible. It is the best of both or the worst of both depending on your point of view.

So lets say for example we have a pipe fitting. Believe it or not pipe thread can be sealed with any of the above types of sealant. Really.

So first off locktite, not the brand the STUFF. If used in small gaps on clean shiny metal locktite is super strong. Instead of tightening the fitting to make it seal I can apply locktite, tighten it snug, and let the locktite do it's thing. The locktite will "tighten" the fitting FOR me! If I have a 90degree fitting that must point a particular direction this is handy. Wait a minute, do I even need threads anymore? Nope. If I have a hole to plug I can make a slightly tapered pin that fits the hole, then I rough up the surface and clean everthing. Then apply locktite, stick it in and PRESTO. Instant leak free plug. Locktite is used as a sealant on core plugs and oil galley plugs by Cummins. Ford/International uses it to seal the injector tubes in the heads of all those diesel pickups everbody likes these days.
But to use a sealant that hardens like this the parts must be solid. it can't be used on joints that move or flex even a little bit. If you try to seal the case with locktite threadlocker it will break up and turn to powder as the case halves shift and flex. Thus the reason for type #2, non hardening sealant.

Using a nonhardening sealant on pipe thread is handy if you need to remove the plug from time to time. Since certain types of sealer never harden the cleanup is easy, or perhaps not needed at all. Just apply a bit more and that's that. You might call teflon a nonhardening sealer, that brown aviation sealant goop is another common example, it does have thinner in it to make it easy to apply, once the thinner evaporates what is left is kinda like chewing gum or dried maple syrup. Easy to work with.
You could loosen the fitting and then tighten it again and the sealer will just move with the fitting and keep it sealed. Can't so that with silicone or locktite.

Silicone can also be used on pipe thread. I have seen it done several times in applications that require extreme chemical and heat resistance. The problem with silicone is it does not seal or hold as strong as locktite, nor is it easy to clean up like the nonhardening goop. It adheres to the surface so you have to scrape or brush or blast the dang stuff off again and it sucks. Silicone does adhere to surfaces and remain flexible, take it or leave it that's what it does.

So there you go, a whole page about sealing pipe thread.

[djkeev]

So, you want opinions on what to seal and to know what is used on a rebuild??

The # 1 problem with silicone in an air cooled VW engine is that the engines lack an OIL FILTER.

The best the factory did is to install a dome made up of metal "window" screen through which most oil must pass. Not all of these screens have the same size openings, many are damaged and compromised, some aren't even there any longer!

Silicone is most often misapplied using the "more is of course better" mentality.
As a result there is massive oozing of the product both on the outside as well as the inside of the case.
Silicone also "hardens", no longer a liquid but becomes a squishy blob of solid material.

If any one of these squishy blobs breaks off and makes it's way to the oil pick up tube and is sucked up through the pump and forced into the oil galley, it can do horrendous damage. These opening aren't large and some (such as the # 4 main bearing) are reduced down to a minuscule size. Most of the oil passaged end at solid metal like a crank bearing journal or a lifter.
The silicone blob gets stuck in these places and clogs up the system starving that rotating or moving part of oil.
What is the result? A spun bearing, a seized lifter, whatever, none of it good.

Why take that risk? Sure if you put the "perfect" amount of silicone on the case seam you CAN make it work but let's be honest, most people don't know what the perfect amount is and use way too much of the stuff because they for sure don't want a leak!! There is NO way of knowing how much squeezed into the case and will form a blob that can dislodge and can ruin your engine.

There is also concern that silicone can only be compressed so far leaving a thin layer of sealer. When depending upon bearing crush to hold the mains in place, that thousand of an inch can also play into engine failure as well. The non hardening sealers are little more than sticky water and squish out almost entirely to bare metal.

Hence the use of non hardening sealers. They don't form artery clogging blobs that break off and destroy your engine.
What type you use is up to you and your research.

Silicone will also break its seal if moved even a tiny bit. Many people use it for sealing the cylinders to the case but IF you pull a head off for some reason you've now got to pull the cylinders and reseal that joint.

I don't use silicone on an ACVW engine at in an ANY location. I do use it on water pumpers in certain limited spots.
I use the Permatex aircraft sealer for the case seam.
I use Halomar for the cylinder to case seal
Most gaskets I put in dry with no sealant at all. They most often seal just fine and don't leave a mess behind to clean up. The valve covers need the good cork gasket that seals well. You remove it so frequently that using a sealer just makes adjusting the valves all that much harder to do!
Honestly, I just built a 1600 and wish I used some sealer on the oil pump gaskets, a little weeping is going on there. I'll pull it off and fix that soon, probably use my non hardening Halomar.
I use a dab of Permatex or Halomar on the case studs and under the head washers and on the threads to prevent oil weeping along the threads and causing a leak.
The metal gaskets on the exhaust and intake manifolds go on dry. Keep extras on hand for service work for they can't be reused and still seal properly. I keep an entire overhaul gasket kit on the shelf for service work.

Put nothing on the pushrod tube seals but do make sure they are stretched to the proper length and do put the seam UP just in case a seam should fail.
Put nothing on the oil cooler seals, again, why risk plugging an oil passage?

Something of note that is rarely mentioned when doing engine service work is the use of copper nuts on all exhaust connections. Without these the ferrous metal nuts WILL rust to the stud and will at best remove the stud from the head, at worst break off upon removal attempts. The nut will also rust and lose it's hex size so it becomes a project to remove when the time comes for no wrench properly fits it any longer.

Educate yourself, do what YOU think is best to use on any given application.

About new cases being assembled dry in Germany? I think that based on the wording in the Bentley service manuals they expected a sealant to be present that needed to be cleaned off before reassembly.

"Use a non-corrosive solvent to remove all traces of old sealing compound from joining faces"

later on it says.....

"Spread an even film of sealing compound on joining faces of the crankcase halves."

They don't specify what that sealer is!! Plus, technology on sealers has advanced significantly since the 60's. Even with that technology surge, stay away from silicones. If you have installed an oil filter, it's not such a big deal for any particles, suck as a silicone blob, will be trapped in the filter.

Anyway, enough of my 2 cents!!!!
Dave
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