ATF RTV?

Anyone here use Mopar ATF-RTV when resealing transmissions or transfer cases? I couldn't find any mention of it here when searching, but a google search brings up lots of hits suggesting that you should use RTV specially formulated for ATF resistance when sealing parts that use ATF for lubrication.

I ask because after installing my SYE kit I found a tiny bit of ATF seeping through the seam at the bottom of the TC, and I haven't even refilled it yet!

Well, I wiped away the fluid and within about 10 minutes, more was starting to seep out. Figured I had no choice but to split the case and try it again...:bawl:

Since I just did my SYE 2 days ago, it went much quicker this go round. Split the case and much to my surprise... the RTV was still wet!!! All the stuff that had squished out was cured, but the entire "gasket" area was still soft, seemed even softer than it comes out of the tube. I had done what I felt was my best prep job ever on this and it has been sitting for 2 DAYS, with no ATF in it other than what has dripped off the chain and oil pump. Fortunately this made prepping the surfaces much easier as I could just wipe the old stuff off.

Dealership parts department is closed today so Mopar ATF-RTV is out of the question. I decided to do a little research on the Permatex website and found that they actually make a product specifically for transmissions (ATF resistant). Unfortunately it seems to be a little tough to come by at the local parts stores so I did a little more reading. Turns out that all of their more common RTV's except the Copper and the Ultra Grey (what I used) have transmission pans listed as suggested applications. Figures I used one of the only ones that is not recommended. Back to the parts store I go! I'll be looking for:

#1 - The special Automatic Transmission RTV
#2 - Ultra Black (it's advertised as maximum oil resistance)
#3 - Ultra Blue

I think the regular Red or Blue would be fine too, but something about them advertising it as their "first generation 1970-1980 gasket maker" bothers me.

Hope this helps someone down the road... I'll report back as to whether or not switching RTV's solves my leaking issue.

I've had trouble with the blue or "ultra Blue" stuff - I don't use it anymore. I've been using black as a GP sealant for a number of years without issue, so I don't see as it would be a huge issue (although I haven't worked on anything using MOPAR ATF +3/+4, I wonder what they changed? Everything I've been dealing with for the last dozen years or so has taken Dexron II/IIE/III/V.)

If you've had trouble before, try this:
Make the layer as smooth and even as you can with your finger.
Let it set up for about a half-hour (soda and sandwich time.)
Install the case halves loosely - just set them together, and tighten the screws finger tight only. Go do something else for a half-hour or so.
Come back, and gently torque the screws to spec (probably somewhere around 19-21 pound-feet. If it's listed, it's on my site - all of my specs are culled from FSMs.)

That should give the RTV more time to cure, which should help. I've used this on difficult seals before.

Also, if you want an alternative, there's LocTite/Permatex #518 "Gasket Eliminator" that I've used on stuff where gaskets just couldn't be had - I did the "industrial mechanic" thing for a while, and worked on some stuff where service parts when out of production before I was born! It's what I use when RTV becomes difficult, or when I need something better (like valve cover gaskets.) It takes a little more time to use properly, but it hasn't failed me yet! Search for my posts on valve cover gaskets to find out how to use it, as I know I've covered it a couple of times.

5-90, thanks for your replies on both my threads. I appreciate the advice as I really don't want to do this a 3rd time. I'll give your method a try and hope for the best.

Just to add to my previous post, a little more research revealed that Permatex's suggested uses for each type of RTV are different depending upon where on their website and/or packaging you look. After looking at multiple sources of information, seems they suggest all of them for most anything... so please, take my previous post as informational, but not the last word when it comes to RTV.

fyrfytr1717 said:

5-90, thanks for your replies on both my threads. I appreciate the advice as I really don't want to do this a 3rd time. I'll give your method a try and hope for the best.

Just to add to my previous post, a little more research revealed that Permatex's suggested uses for each type of RTV are different depending upon where on their website and/or packaging you look. After looking at multiple sources of information, seems they suggest all of them for most anything... so please, take my previous post as informational, but not the last word when it comes to RTV.

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Yep - that's why I give recommendations based on my own experience, not manufacturer product literature. At least I know what I did worked - as you've just found, MFR lit can be a bit spotty and a lot inconsistent!

I've never had any trouble with any of the RTV's (cheap, expensive / brand name or store brand) leaking on the trannies I've done. I've seen other peoples RTV seals leak (straight from the dealership) and always figured it was prep.
I always use acetone for the final three or four cleanings. Aluminum is porous, the fluid leeches back out of the casing after the surface cleaning. I learned that trying to epoxy and/or weld cases.
Make sure your vent is open.
I tend to do mine the way 5-90 recommends, which works especially well on valve covers. With a very thorough prep and 5-90's method I've never had one seep.

RTV sealants "cure" with moisture(they depend on the humidity in the air) Apply and let it sit for at least 15 min. If the air is really dry, 30 or 40 minutes is not out of line.

I use Permatex Ultra-Blue on tranny pans and differential covers. As it says to assemble immediately on the package, I've never let it cure before tightening fasteners, but I always wait an hour before filling. Never had a leak. As mentioned, PREP is definitely the key! All traces of former gasket material/rtv must be gone and the sealing area cleaned thoroughly with carb cleaner/brake kleen, etc.

Resealed my transfer case yesterday and as mentioned previously, it goes much quicker the second time around. I used the Ultra Black and followed 5-90's method. Applied the RTV, mushed the line down into more of a flat bead, waited 30 minutes, pressed it into place loosely (just 'til I saw a little start to sqeeze out), waited another 30 minutes, then methodically snugged and torqued each bolt to spec. Guess I'll find out how I did tomorrow morning when I get home from work.

I didn't realize aluminum could continue to leach fluid out after cleaning. Wonder why it doesn't leak all the way through the housing then? For surface prep, I usually scrape off the big stuff with a plastic scraper, remove the residual with a stainless steel "tooth brush", buff with a scotch brite pad, clean with brake cleaner, wipe down with a paper towel soaked in purified water, and finally wipe down with a clean dry paper towel. I'm assuming this is sufficient? Maybe another time or two around with the brake cleaner?

I used the Mopar ATF RTV, and I haven't had any issues with my t-case leaking. I split the case and put a Terra low as well as the SYE, and no leaks. I scraped the surface with a razor blade and wiped down with acetone prior to sealing.

I had the tube lying around from changing the tranny fluid on my wifes old Liberty. I'm not sure if it's any better, I was just told by Jeep when I did the fluid change that it would not mess up the sensors in the tranny of the Liberty.

It's leaking again...:bawl:

Works just fine, but it's leaking about 3-4 drops per day. It's seeping from the same place again too, the seam right between the magnet and the oil pick up screen. I'm just going to let it leak for a while as I'm tired of working on it and have other projects to tackle. However, I have plans to install a belly skid plate in the next week or two so I guess I really won't be able to wait too long.

Next time, I'm going to try the Mopar ATF RTV. I'm also going to use acetone instead of brake cleaner and I'm going to go over the surface at least three times to try to eliminate any possible seepage from within the aluminum. Diffs have always been so easy for me, I don't understand why I'm having so much trouble... :dunno:

You sure you don't have a crack there? Seems like you are doing waaaaay more than I ever do to seal a case, and still having seepage. I usually use a razor blade to get most of the gasket off, shoot it real quick with brake cleaner, wait a minute for the brake cleaner to evaporate, then slop a bunch of regular black on, and bolt it together about 50% tighter than spec.

Looks pristine to me. I've never hit it on anything and there's no gouges on the surfaces. Not to mention you can see where the fluid is seeping from the seam.

I'm thinking maybe the low summer time humidity here in central CA could be contributing to my problem. It's only leaking from that one small portion of bottom seam which leads me to believe that the leak is being caused by the residual ATF in the case contacting the RTV before it has a chance to cure properly. I wipe down all of the TC internals before reassembly, but maybe I should be spraying them down with brake cleaner to keep them from dripping on the curing RTV? Will spraying the inside of the case harm any of the seals?

A few years back I switched over to Yamabond,its the best sealer Ive ever used!

I have always used ((please pardon my spelling) anarobic sealer- looks like red jelly. not a case leak yet

RCP Phx said:

A few years back I switched over to Yamabond,its the best sealer Ive ever used!

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Which # Yamabond are you using? I'm guessing 4 or 5?

bcmaxx said:

I have always used ((please pardon my spelling) anarobic sealer- looks like red jelly. not a case leak yet

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Something like Loctite 518? Looks like this may be a winner.

fyrfytr1717 said:

Which # Yamabond are you using? I'm guessing 4 or 5?

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Well theres a good question,I didnt even know they have more than one(it sounds like #5)!Its grey and stickier that sh!t, I'll have to see if I have a tube around!
http://www.yamaha-motor.com/sport/apparel/apsubcontaineritems/3/123/all/1/detail.aspx

RCP Phx said:

Well theres a good question,I didnt even know they have more than one(it sounds like #5)!Its grey and stickier that sh!t, I'll have to see if I have a tube around!
http://www.yamaha-motor.com/sport/apparel/apsubcontaineritems/3/123/all/1/detail.aspx

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looks to be the same as toyota uses on pans etc. and fuji bond used by subaru.

Well, I decided I should post back here to provide some closure to this issue. I managed to seal my transfer case properly the third time around and learned a few things along the way. First off, Loctite 518 kicks arse (more on that later). Second, I'm definitely still a newb when it comes to wrenching on the ol' XJ (more on that later too)...

Prior to splitting my case, I needed to find my sealant of choice. My original plan was to use the Mopar ATF RTV for round three, but after doing a little reading I decided to use anaerobic sealant. I read my FSM a little more closely and found that it actually calls for "Mopar Gasket Maker" for the main seal. Turns out that Mopar Gasket Maker is anaerobic sealant. I called all my local Mopar stealerships and found that only one of them ever carried Mopar Gasket Maker, and they had just sent back all their stock because no one was buying it.

I did a little more research online and found that Mopar had actually worked with Loctite to develop this "Gasket Maker" for use on their aluminum cases. This product later became Loctite 518. I then called around to all the local auto parts stores and found that none of them carried Loctite 518. Hit the internet yet once again and found that (much to my surprise) Permatex and Loctite were related. Permatex was actually a subsidiary of Loctite until they split in 1999. I guess that explains why they carry so many similar products. One of those similar products is Permatex 51813. Called the auto parts stores again and found that one of them carried Permatex 51813. Permatex it was!

Moral of the story, if you look closely you'll notice that even the tubes are the same:

Mopar Gasket Maker


= Loctite 518


= Permatex 51813


Round three... disconnect the driveshaft, pull the SYE yoke, remove the rear retainer, split the case. I was beginning to feel like a pro after having done this three times in the past two weeks. I noticed however that the rear retainer and the rear case half were very difficult to pop. I was getting worried that I was going to break something before the RTV (Permatex Ultra Black) finally gave way. I guess the advice 5-90 provided earlier in this thread made for a very strong bond. So then why the hell was my TC still leaking?!?! Here comes the newb part, see if you can guess... I installed my SYE kit with the TC still in the vehicle. The FSM advises that you should apply the sealant to the front case half and then install the rear case half. I wasn't about to apply RTV to a vertical surface, under the vehicle, with oily TC internals protruding out at me when I had a perfectly good rear case half sitting on the garage floor in front of me. Anyone see where this is going yet? How about a picture to help you out a bit...



Well, it turns out that the front and rear case half mating surfaces don't quite match up with each other, especially in the area of the magnet and oil pick-up screen. As you can see from the above picture, most of the RTV bead I applied at the very bottom of the rear case half never even touched the front case half when I pressed the two together. :anon:

I cleaned the mating surfaces up and degreased them with a round of lacquer thinner and two rounds of brake cleaner. I applied a bead of Permatex 51813 to the rear case half (following the correct pattern this time around) and then smeared it into an even layer with a Q-tip. You have plenty of time to make this purdy as the sealant won't start to cure until it is deprived of air. I pressed the two halves together, installed a couple of the bolts finger tight, and then realized I had forgotten to put the oil pump pick-up back in.:doh:

I quickly pulled it apart again and much to my relief the sealant hadn't started curing yet. I added a little more sealant in the areas it looked thin, re-smeared, and re-installed. I installed all the bolts finger tight and then immediately began to bring them up to torque in the recommended "star" pattern. The extra that squeezes out needs to get wiped off as it will never cure so long as it is exposed to air. It's a little messy getting it all off, but it looks nice and clean after you're done. The FSM calls for Ultra Grey for the rear retainer so that was what I used. I also used the Ultra Grey to seal the splines in the bore of the yoke. I let it all set up overnight and then refilled my TC. It's been over a week now and no sign of leaks or seepage! :yelclap:

So what did the newb learn?

Round 1 - I think the Ultra Grey didn't set up due to oil seepage from the pores of the mating surface and oil dripping off the chain. My pattern may have been wrong as well, but it was hard to tell as the RTV was soupy.

Round 2 - Would've worked, but my gasket pattern was wrong. Make sure you look at how the surfaces mate together before applying the RTV!

Round 3 - Worked like a charm. Anaerobic sealant is a little expensive and a little sloppy to use, but works very well.