Sealing cylinder to boiler joint on 1 1/2″ Allchin traction engine

[Malcolm Farrington 1Participant @malcolmfarrington1]

I have had my first attempt to mount the cylinder block assembly on my Allchin boiler. The boiler had a slight depression where the intermalreinforcing has been silver soldered during construction. This means that it is not possible to get a perfect fit between the cylinder saddle and the boiler. I used Hylomar red joint sealant without a gasket but the joint leaked badly at low pressure. I would welcome advice on getting an effective seal.

I also have minor leaks in the joint between the slide valve box and the cylinder assembly. to seal this I will have to remove the cylinder block to get access to the lower internal screws and start again. This can be a permanent joint. Has anyone tried soft soldering this joint? I see a very frustrating time trying to seal this joint and only finding out after remounting the cylinder assembly. It would be a shame to get the main saddle joint to seal and be left with a leak from the valve box seal.

Has anyone found a way of testing the cylinder/valve box assembly before remounting on the boiler?

Thanks, Malcolm

[Malcolm Farrington 1Participant @malcolmfarrington1]

[nigel jones 5Participant @nigeljones5]

I once had a very similar issue. It was resolved by spreading a light coating of jb weld across the surface and then fitting the cylinder. I never tried to get it off after this and the seal was perfect. Jb weld can easily handle boiler temps and pressures in this application.

[Malcolm Farrington 1Participant @malcolmfarrington1]

Hi, Thanks for your reply. I will keep this option for the future if other means fail.

I am concerned about the epoxy setting before I complete fitting and tightening all the screws and also about getting the joint apart if it still leaks.

I have some Blue Hylomar non setting sealant that I will try first.

Thanks again

Malcolm

[JasonBModerator @jasonb]

The black & red tubed JBWeld which is the one you want has a long working time and needs at least 24hrs to harden up so there should not be a problem getting things together.

If you want to pull a joint apart again one surface probably the cylinder can have a smear of vasalene applied to act as a release agent or a sheet of thin polythene put between cylinder and the JB weld which will allow them to be parted. You would have to do this first to get a good mating surface and then bolt the cylinder down afterwards when it has set as the JBWeld will get onto the studs so you would not be able to get them out and that will mean the cylinder can't be removed.

J

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