Sealant for transmission and rear differential

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Was wondering what you guys are using for sealing up the transmission and rear differential .


Looking at the Permatex site and it can get confusing to say the least.

Wondering if the Permatex right stuff 1 minute gasket maker would be my best choice for both.

Figure the rear differential will be easy to get the sealant applied to and ready for install but will

I have enough time to get the transmission pan in place and bolts torqued down ( site says 5 minutes )

Also curious as to what product you all would suggest to clean the pan and differential covers with

before applying sealant.


Last but not least, what side are you applying the sealant to ?

The trans filter kit comes with a gasket but should I apply sealant on top of gasket, then install pan back on housing or apply sealant then gasket them mate to transmission housing ? want to make this as easy as I can while keeping the gasket in place so all of the holes line up. thanks for your thoughts
 
My vehicles use either a reusable gasket or a drain/fill plus on the transmission, so I don't use anything there.

For my front/rear diff's I just use a tube of Permatex Black RTV maker. Apply around the perimeter and each bolt hole of the cover, mate it up, bolt it up, wait about 10 minutes, fill it up and you're done. I hit the cover with the wire wheel which makes quick work of cleaning up the old gasket material and do the diff itself with either a manual wire brush or a wire brush on the air drill. Stick a rag in there first to keep all the [censored] from getting in the diff. Never had a leak. No nasty chemicals necessary.

I do clean out the inside of the cover in the parts washer, or just use brake cleaner.
 
I have used the Right stuff many times on transmission pans. It doesnt fully cure in 1 minute so you have some time to apply it and then put it into place. I discard the gasket as there is no need for it when using this product. I apply the Right stuff to the pan. Assure everything is clean and re-torque to specs. This stuff is great. I have never had a leak in any diffs or transmissions where it was utilized.

Also, I use Brakleen to assure any oil has been removed.
 
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For the diff use Permatex Ultra Black, and for the tranny do not use any sealant with the gasket, and be very careful not to over torque the pan bolts.

Also after you re-install the diff cover let it set a couple of hours before filling with gear oil.
 
Permatex makes a non-ultra black RTV too. Without surprise, it's available at walmart. Has the viscosity of kid's toothpaste and the stickiness of teflon.

I usually apply the RTV to the part that removes, in your case the trans pan. (Couldn't imagine doing it upside down, to the tranny!) Sometimes it has a nice channel to hold the goo in. Be careful around bolt holes that you don't have so much it goes in over the tip of bolts, hydro-locking them.
 
Thanks for the suggestions so far everybody. sounds like I will pick up the Permatex black black for the rear diff. does the black permatex hold up well to synthetic gar lube like Amsoil. I do have a gasket with the trans filter kit but it is of a cork type material. thought I read on here that the cork material is not as good for sealing. guess I could use a dab or two of the Permatex black to keep the gasket in place while I am installing it. I bought an AC/Delco trans filter kit to fit on my Trailblazer. found out that there are two different kinds of pans, a deep and a shallow pan. any tell tale signs of which pan is on my 2002 trailblazer? maybe I need to measure the depth of the pan while it is mounted? bought the kit at Advanced Auto and they only had the one model number, Rock Auto lists both models.
 
I am using the Red RTV on my Differential with the Amsoil Lube, but the Black RTV is fine, just stay away from the Blue RTV.

After I put the diff cover on and tighten down the bolts I like to put a bead of silicone around the cover where it meets the differential.
 
Yes the Ultra Black will hold up well with synt gear lubes. Just let it cure for a couole of hours before re- filling. Acouple of dabs of sealer on the tranny gasket won't hurt just to keep it aliegned.
 
I've used gaskets for both apps since that's what my cars/trucks had. I make sure everything is clean then wipe it down with brake-clean. I spray Permatex Hi-Tack spray on both surfaces, then both sides of the gasket and seat the gasket. Then I put everything together, let is sit about an hour before adding oils or fluids, no leaks doing it that way for me. JMO
 
For what it's worth (not much), I spoke with the Permatex guys a few years ago looking for a "better" RTV sealant for a unique application. Back then, they told me the Ultra black was one of their "best" RTVs and was much better than the plain black/blue etc.. The Ultra Black had better adhesion/leak sealing properties, temp. resistance, and on and on.

There's lots of opinions on gaskets and sealants. The Right Stuff intrigues me. There are gasket dressings like the Hi Tack dermapaint mentions and stand alone sealers like the RTV. I was taught to use most gaskets without anything (Felpro often says this)unless you have problematic mating surfaces. I was also taught not to use RTV with a gasket, but I know others that do.

The Felpro tranny gaskets are superb. I don't like cork ones because they are too easy to squeeze out.

To each his own.
 
I've always used Permatex copper Hi-temp. Yeah, a little overkill but never failed me like the black or blue types. It is a bit more chemical resistant than those, too.
 
Originally Posted By: GMBoy
I've always used Permatex copper Hi-temp. Yeah, a little overkill but never failed me like the black or blue types. It is a bit more chemical resistant than those, too.


+1
I can't see the black being any better. Copper would be better I would think.
 
Clean with spray brake cleaner.
Premium RTVs are good. Black, grey, copper, or blue.
I said premium - spend a dollar more!
A clean and dry substrate, and proper cure time before contact with oil is essential.
Coating only one side and then assemble it is good, but I smear a little on both. No voids or thin spots.
 
I use a gray sealant that I get from the Parts Department at the Dodge dealership. It is made especially for differentials and applications involving gear oil. It sets up and cures very quickly and I have never had a leak with it. I clean the mating surfaces with a razor blade and brake cleaner, then I use a shop rag with a little laquer thinner on it to remove any trace of residue. I only apply the sealant to the cover side and I never use a gasket. I always wait a few hours before refilling the differential, but the directions don't call for that. The sealant is supposed to be formulated so you can put the vehicle back into service right away.

This sealant costs more than Permatex, and is probably made by Permatex for Mopar. But it works very well and I have never had a single problem with it. One tube is about $10.00 at Dodge but it will seal the differential cover 3 times.

Luckily for me, I don't need a sealant for my transmission. It's a manual and I just need to put a little thread sealer compound on the threads of the drain plug.
 
Wow, thanks for the of the input everybody. going to get the diff cover off and drain the fluid in the next couple of days. will have the rear diff cover clean and let the sealant set up for a couple of hours before refilling the rear diff. now have to figure out if the transmission is the shallow or deep pan .
 
Originally Posted By: matrass
Wow, thanks for the of the input everybody. going to get the diff cover off and drain the fluid in the next couple of days. will have the rear diff cover clean and let the sealant set up for a couple of hours before refilling the rear diff. now have to figure out if the transmission is the shallow or deep pan .


I would try to let the sealant set up for 12 to 24 hours if you can. I believe the back of the tube says it cures in 24 hours.
 
A couple hours should be enough with Ultra Black. I think it says to wait one hour before filling on the tube.

I was in a rush when I was putting the cover on when I changed my diff fluid. It was about to rain, so I went ahead and filled the diff after the sealant had been on for a little over 30 minutes (maybe 45 minutes). I haven't had any issues. The outside of the diff is bone dry. Hopefully next time the weather will allow me to wait at least an hour before filling, but a full day is probably overkill with most sealants.
 
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