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how do you RTV?

2K views 30 replies 16 participants last post by  fishadventure 
#1 ·
So crazy odd question. How do you prefer to use RTV?

I'm hoping to actually start a SYE install next week, of course I've been saying that for the last several months and well... it seems life just keeps throwing me curve balls. Anyway, I've noticed on several instructional videos after applying RTV then smear it around then wait 1 hour before mating the case halves. Is that common procedure with RTV? In the past when I've used RTV (which I learned from my dad) the procedure goes like... squeeze it out and install the part. I can't recall ever seeing my dad smearing it or waiting an hour.

Just thought I'd ask before I wreak havoc on my case.

Oh, and yeah, as a follow-up.
I've seen videos where they use Red RTV or Black RTV, anyone ever use Green RTV for transfer case applications?
https://www.permatex.com/products/gasketing/gasket-makers/permatex-gear-oil-rtv-gasket-maker/

I'm just wondering if high temp is actually needed here or if I should use green instead?

Thanks in advance for comments and life lessons.

-Bear
 
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#2 ·
everyone has there own method, based on the individual successes respective to application. I'm almost all around on lubelockers now (which is how i prefer to use RTV :laugh: ). But before that, on my differentials, I would smear it (success). No success smearing on my transmission pan like EVER. Then again, I could never get the transmission pan to seal properly. (thankfully i am changing it out this week and going lubelocker on that).

Just did my SYE this past weekend, i ran a 3mm bead along one mating surface and around all bolt holes. Put the mating surfaces together and snugged the bolts til it just popped out. Left it there for an hour, then went in a torqued them. No leaks yet.

When i use to smear, i didn't wait the hour - i just torqued.

So really, all the write ups and everything I've seen - everybody has there own preference. With no rhyme or reason (or no mention therein of such) . this made me chalk it up to personal preference based on experience.
 
#3 ·
Bruin is right,

Ask 10 jeepers, probably going to get 8 different answers and 2 people telling you to ask jeep forum.

One thing to keep in mind is not all RTVs are made equal. Read the tube! Some are for different oils, heat, and surface applications.
 
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#4 ·
Definitely going to get lots of opinions! My personal humble opinion is the smooth even coat, finger it smooth around the flat surface then tighten the bolts just until squeeze out occurs. Then I wait about an hour and come back to properly torque it. More than one way to skin a cat!
 
#5 ·
I usually smear then torque, unless some assembly instruction specifically states not to.

My SYE leaked so I pulled it, cleaned it and did the same again, it leaked again. I read the instructions again and it said something about running a bead and waiting X amount of time, so I did that about 6 months ago, yep started leaking again a couple weeks ago in Moab. So who knows.

I too am all about the Lube Lockers for things that they're available for.
 
#6 ·
For me, it depends on the type of components I am working with. Sheet metal covers like differentials for example, need a different technique than rigid components like a transfer case.

Smear or not smear, won't make any difference. That is just a matter of how carefully you can apply an even bead.

The real question is whether you want it to skin over for an hour before assembly. I never do that. I want stuff glued together as stuck as possible.

Second question is do you fully torque on the fresh sealant, or finger tight, then wait an hour, and final torque. Here is where the type of cover makes a difference. For sheet metal stuff, I do the finger tight-wait-final torque. For solid components, I slap them up on wet sealant and torque. But what matters more I think is that I clean all traces of oil off the mating faces using either alcohol or acetone. NOT paint thinner, because it leave an oily trace. Again, I want stuff glued tight, not just clamped.

Right or wrong, this is what I do.
 
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#7 ·
Also, for a transfer case, you want the maximum oil resistant RTV. High heat not necessary. Sensor safe not necessary. I would use the Permatex Black.
 
#9 ·
It all hardens in any event - if you are waiting the 24 hours for full cure before replacing fluids. This is not too big an issue. Never had RTV end up, say, in my differentials or transmission.It may make its way into the boundary edge of the internals but it hardens and doesn't ever break off. Again - this most likely depends on just how much/big your bead is to begin with
 
#19 ·
Never had RTV end up, say, in my differentials or transmission.It may make its way into the boundary edge of the internals but it hardens and doesn't ever break off. Again - this most likely depends on just how much/big your bead is to begin with
Just an FYI that your comment reminded me of...

I changed out my factory Trans pan on my 2012 KK. The factory RTV had some missing snittles of squeeze out. Found them lodged in the filter upon dissection.



 
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#12 ·
Thanks for the feedback. Yeah I figured it was a loaded question in that I'd get a lot or varying opinions, but good responses from everyone. I like hearing (or reading) different perspectives on the subject.

bpounds , good comment on the type of material being used, I hadn't thought about it from that point of view.

timatoe, I hope I don't share in your experience with my SYE install. I'm hoping it's a one and done event for me. I'll be good to get the YJ rolling again.

As for the comments about oozing, yeah that's always my fear when using RTV. I can see what it's doing on the outside; but what is it doing on the inside that makes me nervous.
 
#13 ·
I would do 1/8" to 3/16" bead around the surface for diff covers. Then I would finger tight, wait an hour and torque. I recently tried it on my 8.8 after it developed a leak after some odd years. I must have screwed up and got a leak that was worse. I went ahead and got a lube locker. Wish I would have done it years ago. If I replace my D30 cover, I'll get one for it too.

Some prep I do is wire wheel the surface, degrease it. I used to use gasoline but switched to Simple Green. Then I applied the bead to the mating surfaces and set the bolts finger tight. I'm sure everyone is a little different.
 
#14 ·
Permatex just keeps adding new RTV types, I guess that's good, but it makes it more confusing. I was not aware of the green stuff until this thread mentioned it. I guess that is for high vibration stuff.

But I also noticed they have one now for automatic transmissions. Makes me stop and think, since a transfer case uses ATF fluid. Is the product designed to resist ATF better than the Ultra Black oil resistant stuff? Of course, they don't reveal such trivial data.

If they really wanted to help us, they would invent a container cap that would preserve the product for more than a week. I've tried every shop trick there is, and nothing really works well. Best I've found is an electrical wire nut screwed on, but still only works for a short time.
 
#15 ·
I won't buy it in a tube anymore, Permatex has something they call the PowerBead Can and it's awesome, just squeeze the trigger and you get nice consistent RTV. Consistency has always been my problem with the tubes.

Still doesn't last for more than a month or two once you open it though.
 
#16 ·
For all applications I throughly remove any traces of old sealant with razor blade and wire brush or a "roloc bristle disc". Then clean all surfaces with brake cleaner before applying sealant. Sealant is applied in varying thickness depending upon the appliacation and roughness of the surfaces mated. I smear the sealant to ensure that I have a continuous seal with no tiny gaps. I don't wait for the sealant to skin. I join the parts and torque immediately then wait for the sealant to cure before use. I've yet to have a leak using modern RTVs. (Knock on wood) I tend to use either "import gray" or black, however I prefer "import gray"
 
#17 ·
Another thing.... I can't find it on the permatex site but the last time I bought a tube there was an advert type deal on the counter talking about black and grey packaging, black being used on steel parts and grey on aluminum. Never heard of that before and like I said can't even find it on the site now. I think I might try that ATF one this next time.
 
#18 ·
Its best to follow the directions on the package.

Clean, true surfaces are important. Clean with something that leaves no residue. Brake cleaner is my favorite. Acetone, and alcohol work as well.

I spent years RTVing gaskets onto the intake deicers for the Predator/Reaper, Etc drones and they specified that it be assembled wet within five minutes of application to preclude skin over.

Letting it cure 24 hours before filling is also recommended.

For your transfer case, any color will work(except blue). Factory was black FWTW.
 
#21 ·
Another thing to add which I haven't seen mentioned yet, especially whenever one has multiple projects going on, its to purchase a caulk gun cartridge of RTV instead of the tubes. I didn't know such existed until I saw some gathering dust tucked away on an ankle level shelf at the local O'Reilys. The full cartridge is maybe $14 or so, vs $5 for only a few ounces with the metal tubes. It fits in any regular size cartridge gun; put it straight on to a large part like a tcase case half or put some on a piece of cardboard and dab it onto a smaller part with your finger.

I've been using the same cartridge for over 6 months and it hasn't dried out or sealed up on me yet. When you're done using it for the time being, stick a large nail down the tip to keep it fresh until you need it again.

Sent from my SM-G860P using Tapatalk
 
#22 ·
timatoe said:
Another thing.... I can't find it on the permatex site but the last time I bought a tube there was an advert type deal on the counter talking about black and grey packaging, black being used on steel parts and grey on aluminum. Never heard of that before and like I said can't even find it on the site now. I think I might try that ATF one this next time.
I don't know if the ATF one is different or not.

HOWEVER we are in a place in time where very few "new things" are actually being developed. Rather, new things these days are a repackaging of an existing product. Most things are now intended primarily to separate you from your money, not solve a problem.

Essentially four products that have been around for 30+ years are all we need. Since these products have been used successfully for decades' any "new" item imho is trying to solve a 'problem' that doesn't exist! This is only for engines, diffs, and such- windows, body sealants and such are a totally different family of products.

Gray "import gasket maker" for aluminum or other surfaces that aren't truly flat. It dries 'tough'. Not good for surfaces that need to be torqued to, but that is true for every retail RTV.

Hylomar HPF for surfaces that tolerance and/or torque needs to be applied, where a product that doesn't effect torque settings or clearance specs (VW engine cases, some hydraulic pumps, etc). I can't think of anything jeep I'd use it for.

Black RTV- good for nearly everything as long as the surfaces are clean and pressures aren't high (diff, water pump, Tcase, etc.). Good General goop.

High temp. (Orange) best for stuff that....... well most often like 99% of the time it isn't needed for anything, ever! Needed is the key word, it works fine a lot of the and is ugly to see it squeezing out everywhere.

Additional two others:

A fantastic but limited use item is the old Indian Gasket Sealer- gasoline resistant and great for problematic carb repairs or vac leaks in the field. Good for other stuff when you need to or HAVE to reuse a gasket that should be replaced but you can't at that moment.

Add a ptfe pipe thread compound and you as the mechanic don't need anything else, ever.

The Gray Stuff as Bob Hoffman called it is probably the one I use the most because it's tough, but black is very simple and probably sufficient, and some cases maybe preferred because it is softer.

No matter what you use, though, 99% of the time, other than letting a product 'skin' according to the product label, if you let a gasket maker 'set' you defeat one of its primary benefits: curing and making a seal in place. If it sets, the gasket-maker product will be harder in thinner spots, not allowing the seal to be made properly and warping things like stamped steel rocker covers and such. Then, in order to tighten them down, you leave almost no product in some areas and a big glob left to maybe seal other areas.
 
#24 ·
Just installed a deep dish for my transmission last night and chose to go the smear route, RTV Blue.... i didnt bother with the gasket (my lubelocker will not make it in for a couple weeks cuz im cheap and chose standard ship).

With the tranny pan... those indents and grooves on the mating surfaces always irked me. So i slathered it to see if this works better. My tranny has never been sealed properly... leaks within hours of adding fluid and firing it up. Gonna see if this method is better (or worse). I've always used the gasket + rtv. Not this time
 
#26 ·
My tranny has never been sealed properly... leaks within hours of adding fluid and firing it up...... I've always used the gasket + rtv.
Never use RTV on a gasket. RTV, or gasket, never both. Of course there are limited exceptions such as the dab on the corners of the oil pan joints, but trans pans and valve covers will leak that way.

Many times, the faying surfaces are designed in such a way that RTV is the appropriate/preferred sealant. Others, need a fibrous gasket and are designed with that in mind.

And then, you sometimes find a factory "lubelocker" :)

 
#29 ·
Well, thought I'd circle back and close out this thread.

I used the black RTV, ran a small bead around the case half and then smeared it trying to put more close to the outside of the lip than inside to minimize squishing inside the case. Mounted the case half, tightened the bolts to just seeing the squish then waited 1 hour then torqued all bolts.

For the other part I ran a small bead and only smeared where the lip was narrow, all other places left it alone. Did the bolts the same. hand tighten till I saw the squish, waited an hour then torqued.

About 22 hours later I added the fluid. Yeah I just couldn't wait the 24 hours, I had to rotate some tires.

So far no leaks.
I sure hope I didn't just jinxs myself in saying that.
 
#30 ·
I have had great luck with the Permatex RTV products. Used the Universal Blue on the transfer case and have never had any leaking. First time was on the complete rebuild and second time was when I installed the SYE. They recommend to hand tighten the bolts until the RTV starts to "Squeeze" out, let it sit for an hour then tighten. It "fully" cures in 24 hours so I never put any fulids in until after the 24 hour cure time.

Also used it on a Kohler engine on my Zero Turn that was leaking oil from both valve covers. Followed the same procedure and hasn't leaked since (~3 months).

The key is letting the material setup before final tightening.

https://www.permatex.com/products/g...-blue-multipurpose-rtv-silicone-gasket-maker/

I used the "Black" which is recommended for Diffs and the instructions say to tighten without "squeezing out" the RTV. I tightened mine so I saw it just starting to "bulge" out. Waited 24 hours to fully cure. tightened the bolts a 1/4 turn, added gear oil and hasn't leaked a drop. That was done last fall.

https://www.permatex.com/products/g...m-oil-resistance-rtv-silicone-gasket-maker-4/
 

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#31 ·
I like my bolts tight - not ready to fall out. At least tight to torque specs doesn't seem like too much to ask. The instructions on the website say "Do not squeeze out silicone by over tightening bolts. Re-torque will not be necessary." Also says to use a 1/16" to 1/4 bead.

My stuff never leaks - and now that I think about it, doesn't break early - so I think I will stick with the methods I've used for thirty-five years. That way I don't have to leave my bolts loose and then try to figure out what over tightening the bolts actually is? :laugh:

I mean, it's not like a jeep ever has anywhere close to design tolerance of loading on any bolts or anything, right?!
 
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