Caulking a saddle tank.

[Dennis RaynerParticipant @dennisrayner52782]

I am plagued with persistant leaks from the front of the saddle tank on my 7¼2 gauge Hunslet. I'm talking about the seam closest to the boiler but hidden behind the smokebox rear. I wonder if that is the problem? That perhaps the smokebox temperature is causing the caulk to break down. I have tried araldite and car body putty. Still no joy. Ss you can see, the saddle tank is finish painted and I am reluctant to try a solution (eg soldering) that would need a repaint. I wondered if anyone had any idea as to what "caulk" I might try next?

[Dennis RaynerParticipant @dennisrayner52782]

[Michael GilliganParticipant @michaelgilligan61133]

Dennis,

I'm way out of my comfort zone, but

… have you thought of trying RadWeld ?

MichaelG.

[Dennis RaynerParticipant @dennisrayner52782]

Hi Michael, I had thought of Radweld but I ran into 2 obstacles. The tank has extensive baffles inside so I could not guarantee getting the Radweld to the appropriate area and it needs to be cured by raising the temperature to above (?) boiling point to make it work.

Thanks for the suggestion anyway – at the moment I'm thinking of JB Weld and would welcome any experience of use.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Dennis Rayner on 27/04/2016 22:11:58:

… and it needs to be cured by raising the temperature to above (?) boiling point to make it work.

.

Ah, yes … it's designed for a pressurised [albeit leaky] system.

MichaelG.

[julian atkinsParticipant @julianatkins58923]

Hi Dennis,

I am afraid you will have to take the saddle tank off, poke about from outside at the dodgy bits, then my solution would be to pour in some white enamel so it goes where wanted then blow through the tank lid with other outlets blanked off. You should see a bit of a paint emerge from the dodgy bits on the outside. I thinned the paint slightly first. Obviously any colour paint would do in theory!

This worked on a saddle tank somone else built that I had through the workshop. I tried lots of other methods before the above without success.

Cheers,

Julian

Edited By julian atkins on 27/04/2016 23:28:50

[duncan webster 1Participant @duncanwebster1]

How about the inverse of Julian's suggestion, take it off, identify where it's leaking (immerse tank in a barrel of water and blow into it), clean up the affected area then apply some suck to the tank and paint to the outside. Paint should be drawn into the leak and hopefully seal it off. At least you know the paint is getting the the parts other paints cannot reach (sorry Mr Carlsberg)

[Speedy Builder5Participant @speedybuilder5]

Why not do a proper job and solder it? Clean the inside with an 'active flux' clean the outside where it leaks and apply solder with a good old copper soldering iron and a small gas flame. It would spoil your paintwork, but it would do the job properly.
BobH

[Brian Baker 2Participant @brianbaker2]

Greetings, you have two choices, either take it apart & resolder, or try any epoxy liquid.

This is expensive, obtainable from yacht chandlers, like the "West" system, and works best on clean brass.

Bostick also make a rapid set metal epoxy, but in small tubes.

Keep it warm when it is curing, clean it as best you can, be generous with the quantity, and it usually works for the life of the tank.

regards

Brian

[Mark P.Participant @markp]

There is some stuff called petseal for sealing motorcycle petrol tanks. I have used it in the past whilst working for a model engineering company. You pour it inside the tank, slosh it about for a bit and pour it out. Worth a try.
Mark P.

[Ady1Participant @ady1]

Hot glue gun? The good ones go up to 200 degrees C

[Ady1Participant @ady1]

Devcon is good stuff, used it a lot in the 1980s, a well known auction site has plenty

I rebuilt a smashed up spacebeam with it and carried it about for 5 months on the grottiest tanker ever, tough stuff

[nigel jones 5Participant @nigeljones5]

The easy solution, and one which I have used with complete success is to take the tank off, remove or block any outlets, get it good warm (hairdryer!) mix a half pint of fibreglass resin and pour in. Keeping it warm will make the resin very runny and you can direst it to where you want it. Give it a good slosh round, don't concentrate it where the leak is. Works 100% every time for me.

[Dennis RaynerParticipant @dennisrayner52782]

By way of background I am a self-taught ME with no access to bending rolls. I bent up the saddle tank wrapper over the end plates which led to a less than perfect fit which, after soft soldering, needed some caulking to make it watertight. For this I used Araldite. Everywhere is watertight except the front plate. If I start heating up the boiler I think I will be opening up the proverbial can of worms!

Also I dread painting and it was a major success (for me) to achieve the finish seen in the picture attached to my original post. It's another reason for not seeing heat as being part of the solving the problem.

I really appreciate the various suggestions that have been made and believe that my "least worse" solution is going to involve some internal caulking. I've yet to remove the tank to see exactly where the problem is. Notwithstanding my decision to now seek an "internal" solution, I ordered some JB Weld 4:30 yesterday afternoon and it dropped on the mat at 09:30 today. Excellent service from a company called "Fix The Bog" (Usual disclaimer)

Thanks again to everyone who has taken the trouble to help me on this problem

[john carruthersParticipant @johncarruthers46255]

Maybe Holt's 'seek and seal' ? if it's still available.
It's quite runny and creeps into gaps by capilliary action then sets.

[Dennis RaynerParticipant @dennisrayner52782]

An update (conclusion?)…….. Whenever I've taken the saddle tank off before to fix a leak, I have always found the water seeping from a "hairline" crack and trying to caulk from the outside hasn't given a permanent fix. Hence I welcomed the various suggestions given for caulking from the inside.

Removing the saddle tank this time revealed that about 1½" of the soft soldered joint between wrapper and flanged endplate had opened up! I felt a lot more confident about caulking from the outside so I opened the seam up slightly and put in a thick caulk of JB Weld. I then tapped 6BA through the wrapper and endplate and put a C/S brass screw in to close the gap squeezing the JB Weld filler. 24 hours later and the joint is watertight. JB Weld is good for 500° F so fingers crossed for the next steamup.

Many thanks for all the helpful suggestions.

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