Jointing compounds

I'm doing the final build of my triple expansion steam engine and need to seal the six joints between the valve chests and cylinders plus the HP and LP chest covers. This is not suitable for gasket paper (that would be a horrible job) and I'm not sure I could even get the ingredients for the red-lead goo of my apprenticeship - so what is the recommended modern product?

I would hope I don't have to dismantle the engine but I would prefer something that allows that without resorting to violence and it has to handle steam at 180psi and some superheat.

Loctite produce a liquid gasket that should do the job.

Blue Hylomar is also good.

MichaelG.

Hello Tony.

I would recommend Stags Wellseal Jointing Compound, I have used this for years on full size as well as model engines.

Wellseal is a liquid sealant that is applied with a small brush or spatular and is ready for assembly any time after it has gone tacky, it never hardens or dries out, so dismantling is always possible and it can withstand up to 200 Deg C.

Because it is a relatively thin liquid type sealant, rather than the thicker paste or silicone rubber type sealants, you don't get lumps of it squeezing out of the joint.

It isn't a gap filler, so it won't seal badly warped or damaged mating faces, but it is perfect for metal to metal joints where no gaskets are specified and is excellent for the small delicate parts of a model engine.

Completely agree about Wellseal - we used to use it to seal copper headgaskets onto a 2.5L supercharged race engine - never any issues and could be cleaned off with cellulose thinners.

Simon

Tony, I used Loctite liquid gasket on the steam chest and cylinder heads of a Stuart Turner S9, I don't know how it goes on steam, the engine has only run on air, but I can't see any problem.

Ian S C

Hi Tony, I would go for the Stag Wellseal every time.

Mark P.

Thanks to all

Wellseal it is - but I do remember blue Hylomar from working on dynamometers at Froude

Tony

Stag and Wellseal are two different products, Stag is red and messy and Wellseal is brown and cleaner to use, Hylomar is blue and was used by Rolls Royce and Gardener diesels on all there engines.

Stan

I have been using it for over twenty years, the brown liquid that is easy to apply, particularly in small quantities on small parts, and it's called Stag Wellseal on the packaging, whether a tin or a tube.

Blue Hylomar is completely different, being a thicker paste or jell and is ok for larger joints and can fill and seal gaps to some extent on warped or damaged faces, but I think Stag Wellseal is more suitable for Tony's small engine.

Incidently, Wellseal was also developed by Rolls Royce.

Edited By Lathejack on 24/08/2014 02:06:14

I think Stan is getting confused with Stag Jointing Paste which comes in type A & B (thin & Thick) and that is indeed red

When I worked for the local bus company in the late 50s and early 60s the Guy Arabs had 5LW Gardener engines and no gaskets were used the sump, timing cover and rear housing all sealed with wellseal in tubes.

Stan

Hi Guys,

Thinking of Hylomar, it can be thinned for application with a brush but for the life of me I can't recall what I was told the solvent is, can anyone help?

chriStephens

Chris,

Here is the datasheet ...

They suggest using Acetone for removal of dried Hylomar; so I suppose that must be a "solvent", but I'm not sure if it also works a a "thinner" [it may degrade the material].

MichaelG.

Thanks for that Michael, I'll do some experiments next time I buy a tube.

chriStephens

Chris,

Having looked at the datasheet again, I suspect that the "solvent" is probably Dichloromethane ... which needs to be treated with some respect.

MichaelG.

Edited By Michael Gilligan on 25/08/2014 20:52:31