Hylomar on gearbox 1/2 moon rubber seal to gearbox?

[btetley]

What do you think - to hylomar or not. Also hylomar on paper gearbox to block gasket?

[GraemeC]

I use a thin bead of RTV here - more gap filling properties than Hylomar.

No harm in using a smear of Hylomar on the gaskets though.

[imack]

I've never put any sealant on the 1/2 moon seal

[dklawson]

I use a thin bead of RTV here.

+1

[dodge44]

Traditional Red Hermetite on paper gaskets was favoured in this house but switched to Hylomar when availability of the former dropped off a cliff. Curiously, have since done some tree pruning and was surprised to find Arbrex, which is used to seal the end of a cut branch, appears to be to all intents and purposes the same as Red Hermetite...
Minded to think that unless you are rally driving, the half moon with no sealant works just fine for what is intended - keeping dust out. In reality if you need to put sealer here it's possibly to stop oil ingress so you have bigger problems perhaps more in need of attention?

[Edit for clarity : Apologies, misread OP. My ref is to rubber seal between box and remote arm, not box/block]

[Lakeland997]

The factory may have used RTV on the seal towards the end. This is an MPI gearbox I believe had never been separated from the engine before but I can’t be entirely sure
Anyway, I now use RTV here on all my builds.
Apologies for the upside down image:

75672B27-E4F6-4326-A536-086A28D889BE.jpeg

[iain1967s]

I use a thin bead of RTV both sides on the rubber seal, and Permatex Aviation #3 form-a-gasket on all paper gaskets.

[Andrew1967]

I've never put any sealant on the 1/2 moon seal

I don't either. Main thing is to make sure the seal has located correctly on the gearbox flange.

Hylomar on paper gaskets.

[btetley]

Traditional Red Hermetite on paper gaskets was favoured in this house but switched to Hylomar when availability of the former dropped off a cliff. Curiously, have since done some tree pruning and was surprised to find Arbrex, which is used to seal the end of a cut branch, appears to be to all intents and purposes the same as Red Hermetite...
Minded to think that unless you are rally driving, the half moon with no sealant works just fine for what is intended - keeping dust out. In reality if you need to put sealer here it's possibly to stop oil ingress so you have bigger problems perhaps more in need of attention?

[Edit for clarity : Apologies, misread OP. My ref is to rubber seal between box and remote arm, not box/block]

The seal is the large half circle between box and block at the front behind the chain. I'm just thinking of "extra" sealing protection to stop oil leaks from inside.

[btetley]

I've never put any sealant on the 1/2 moon seal

I don't either. Main thing is to make sure the seal has located correctly on the gearbox flange.

Hylomar on paper gaskets.

Thanks. Good to see what others are doing.

[btetley]

Thanks

[Hipwell]

With the quality of fit of some seals I would be using a bead of RTV and wit the amount of distortion on some
Gearbox flanges, same on the gaskets. Not had a problem upto now.

[Costafortune]

I don't use Hylomar anywhere. Paper gaskets get a thin coat of LM grease and the nuts/bolts torqued correctly.

[bwaminispeed]

I use no sealants at all, except a very small swipe in the corners only of the front half rubber seal.......

ALL paper gaskets are heavily oiled before assembly only...............

[Spider]

I have been using Permatex no. 3 on all paper gaskets that see oil and also the 1/2 moon seal. My reasoning for putting it on the 1/2 moon seal is not for better sealing but to provide some 'lubrication' of the seal when the gearbox is fitted up to it. These seals are bigger as supplied than their final shape and size. I found very early on, when everything is clean and dry, the seal has a tendency to grip the Gearbox case and can pull up quite unevenly, which - as it did to me - can lead to a leak.

The factory may have used RTV on the seal towards the end. This is an MPI gearbox I believe had never been separated from the engine before but I can’t be entirely sure
Anyway, I now use RTV here on all my builds.

Somewhere I have a TB for fitting the replacement seals that can be done with the engine in situ and if I recall, they do recommend a sealant in that, though, I can't recall which.

[Lakeland997]

That could explain it Spider. Could have been a warranty job, fitted by a dealer without splitting the engine/box.
I can't remember now if the seal was the hard (retro-fit) type or the usual soft one.

[btetley]

That could explain it Spider. Could have been a warranty job, fitted by a dealer without splitting the engine/box.
I can't remember now if the seal was the hard (retro-fit) type or the usual soft one.

The hard ones are what I'm using. They were the warranty ones.

[andy1071]

I use a small amount of Hylomar or RTV on the ends of the Gearbox seal (there is far too much used in the picture -the extruded lumps can fall off and block oil passages...).

But for everything else I only use Wellseal.
Don't know if this is available outside UK, though..