Silicon sealer

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Hello, would someone be able to help with a query please? I am machining a set of cylinders, on which the cored ports are misaligned and too large. I am rectifying that by using a separate port face from 1/8 inch gaugeplate which will lie on top of the original, permanently screwed on. My question concerns sealing one t'other. It has been suggested that 'silicon' will do the job; if so, is that referring to ordinary bathroom type sealant from the local DIY shop, or is there a particular type that should be used? Or anything else? Thank you.

[Tel]

Probably one of the 'gasket in a tube' type products. And only the lightest smear. Probably get away with an oiled paper gasket.

[Shawki Shlemon]

Loctite have what they call flange sealant ,it is in tube like Tel says ,it is good .

[jackrae]

Fernox do a silicone type sealant called LS-X.
It's quoted as being suitable for temperatures "above boiling point of water" but who knows what that means. I've used it with great success on damaged plumbing fittings and can vouch for its "lower than boiling point" qualities.
But somehow I don't think that "silicones" are the right sort of thing to be using on good engineering jobs
Jack

[circlip]

Red Hermatite, (probably unobtainable now) Was used to do virtually ALL the sealing on IC engines, full size that is not toys, like Tel says, probably oiled brown paper, much more "green" than silicones.

[steam4ian]

G'day all

This topic could be a page turner! ;D
I've just built an oscillator with milled steam passages in the port block. The port block is bolted to an brass angle and after deliberation used a shellacked paper gasket. Seems to work OK. I did look at using a Loctite "gasket in a tube" but thought the stuff might get in the passages which are only 1.0mm deep. BTW I made sure both surfaces were truly flat before bolting then together.

For my next stationary engine I am seriously considering making the port face separate from the cylinder with milled steam passages. I may soft solder the two together. It saves trying to drill at an angle.

Regards
Ian

[circlip]

Some of the early designs for steam engines in the original Percival Marshall publications of the ME used bolt on port faces, they weren't as affluent as us, hand drill/hack saw and kitchen table, "whats a miller/pedestal drill?"
T'other Ian.

[dickdastardly40]

A smear of hylomar blue from a motor factor could do the trick, this works well on high temp face to face joints but is a b*gger to get off.

Best Always

[houstonceng]

circlip said:

Red Hermatite, (probably unobtainable now) Was used to do virtually ALL the sealing on IC engines, full size that is not toys, like Tel says, probably oiled brown paper, much more "green" than silicones.

Still readily available, as is the "Germatite" Green (Steam) sealant. The Green set hard. The Red is 'orrible stuff and stays "gungy".

I always use Hylomar on car engine paper gaskets. Recommended by Messers Rolls and Royce and the London Fire Brigade Vehicle Workshops - so it must be good.

Petrol and Diesel engine manufacturers often recommend "Liquid Gasket" - which is a form of Silicon Rubber (IIRC it was called something like RTV by Rover for their SDI). It doesn't look or smell the same as "Bath Caulk" - for a start it was bright orange - so I'd suspect it was a different compound. Hermatite make it - available from Halfords

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Thank you very much - very useful.