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BJ8 Transmission Gasket Sealer

AUSMHLY

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The BJ8 transmission rebuild is almost complete.
I have a new gasket set.
What is the recommended gasket sealer to use on both sides of the gaskets.
Brand and part number would be helpful.
Thank you.
 

LAW75

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My understanding is NOT to use a sealer. The gasket, along with the correct torque when tightening is what I have been told. Will double check with my Foreign Car mechanic friend and get back today/tomorrow.
 

vette

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I have used a variety of gasket sealants with paper gasket over the years. I usually like to use RTV Black. But the last time I put a rear end cover on I noticed that there is an RTV sealant formulated just for components using EP rated lubricants. But the Black stuff works just as well. There is also a grey RTV which I used the last time I installed a Chevy intake manifold. It is used on the valley bridge at the front and rear of the manifold. But the grey stuff sets up harder than the black. The black is considered none hardening and is intended for areas that will experience some vibration. In my old days I always used aviation permatex. Trouble free stuff but a pain to remove if that time comes. All these products can be used with a paper gasket. Applying it to both sides with very thin application. RTV is actually designed that it is what is called a "gasket maker" meaning that it can be used without any other gasket material. It just sets up and seals the voids and works perfectly. When I use RTV I let it set just a smiggin before I bolt things down tightly. That way you usually aren't squeezing it all out of the joint. Once bolted down don't touch it for 24 hours to allow it to cure in place then there won't be any leaks.
I believe the older vintage components need some type of sealer because of the variance in their machined surfaces. The reason they usually leak is because they don't have any sealer there.
 
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AUSMHLY

AUSMHLY

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Thoughts on:
Hylomar Universal Blue?
Permatex 80019 Aviation Form-A-Gasket 80019
 

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vette

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I have a tube of Hylomar Blue but don't have much experience using it. I can't even remember where I might have used it. But I do seem to remember that the RTV seems to have more body to it. And therefore I liked it better.
 
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AUSMHLY

AUSMHLY

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I agree, RTV has more body, which may seal better? My concern with RTV is it may squeeze out inside the tranny. As may most sealants. Choose your poison.
 
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vette

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I think your only concern there is if you gobb it on too much. With a paper gasket you just want a small film on the gasket. Also like I said earlier, after you install and tighten things down let the assembly set for 24 hours. The RTV will be fully set by then and cannot separate to fall into the inside of the trans. I have seen some Pro shops squeeze outrageous amounts of RTV on a joint where they have no gasket and it squeezes out all over when they tighten it down and they have no apparant problem that I have every seen. As a matter of fact I had a fellow install new ring and pinion gears for me sometime back and he put so much RTV with no gasket on the joint that I was annoyed how sloppy it was. By the time I got it back to my place it was all set up so I didn't try to redo it. It has never caused a problem.
I hesitate to bring up another thought because I have no assured evidence but it is something about Hylomar. I seem to remember that Hylomar can be attacked by gasoline and maybe some oils. I remember a transmission I took out of a Healey some years ago because the transmission leak about everywhere. When I separated the joints there was no gaskets but whatever sealant was used was just about all dissolved/disintegrated.
It was an almost clear rubbery goo. That litterally was loosing its body and properties. At the time I thought it was Hylomar. Please forgive me if I am unnecessarily speaking out of turn but I would look into its properties and uses before I used it again.
 

vette

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Well I guess you can plop your money down and pick your poison. I did mention that I like aviation permatex. Also he mentioned about too much RTV which I agree. He also was pulling that RTV off the piece. It didn’t fall off. In view of all of your concerns I would tell you to use aviation permatex. Maybe others can contribute some experiences.
 
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AUSMHLY

AUSMHLY

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Lots of options, pick your poison as I originally stated. Hence why I'm asking other Healey owners what they recommend or have used. So far 2 people have commented, and I thank you for doing so.
 

Healey Nut

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If Hylomar is good enough for Rolls Royce then it’s good enough for a Healey .
 

LAW75

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Getting back a bit late, my foreign car mechanic expert who once worked for British Leland, says no sealant on gaskets. Sloppy, peeling off issues which "infects" the inside of whatever you are sealing, when changing gaskets cleaning can be a problem. But sealing sure feels good, doesnt it?
 
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AUSMHLY

AUSMHLY

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Healey's, most older British cars; the engine, transmission mating tolerances weren't very good.
We use a sealant with gaskets in order to help stop the leaking or minimize it.

Did you ask your mechanic if the cars leaked after only using a gasket.

If they didn't... please ask him to share what gaskets he's using. I'm sure there are good gaskets and not so good. Or maybe he's using gaskets made out of a different material then what the usual vendors sell us. Example cork vs the papery type we get. Or maybe his gaskets are thicker and made of a special material?

I'm close to putting the transmission back together. Sure would be nice if it didn't leak. :smile:
 
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Superwrench

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I always had good luck using Permatex Copper Spray a Gasket on thin gaskets like that. Gives you a nice even amount of sealer. 2 thin coats is better than 1 heavy coat.
 

Bob_Spidell

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I used Form-A-Gasket on my gearbox to good effect. I use it exclusively on paper gaskets; in fact, I used it yesterday on an engine coolant valve gasket. Thin coat only; done right, the gasket will peel off intact if you have to disassemble again. Permatex has two part numbers for, apparently, the same stuff; anybody know the difference (guessing '3H' is newer)?
 

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Bob_Spidell

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FWIW, I had my gearbox cover off to replace a heater valve (last one only lasted 35 years). All paper gaskets have a thin film of Form-A-Gasket; brake ring has no gasket--not supposed to have one--but thin film of an RTV (done about 7K miles ago):
 

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Superwrench

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Yamaha made a sealer called Yamabond. I don't know if they still make it or not but it was one of the best sealers I've ever used !
 
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