Want to put a brass union in a Stainless Steel? tube

[Martin King 2Participant @martinking2]

[Martin King 2Participant @martinking2]

Hi All,

My next door neighbour has a very nice Triumph TR3A which at the moment has the front off for some work on the radiator and a general clean up of the now accessable areas.

He has a manually switched Kenlowe fan for extra cooling but wants to take this opportunity to fit a union into the stainless cooling down pipe to take a thermostat for the Kenlowe.

This part is available withe the union already done for £20 or so but we wonder if it is OK to silver solder or JB weld a suitable brass union into the existing pipe?

Seems an easy job? maybe not?

Cheers, Martin

[Nick HulmeParticipant @nickhulme30114]

Plumbers solder will be up to the job for car cooling systems provided the physical fit is well designed and gives adequate area, leaded or lead free.

[HopperParticipant @hopper]

I would spend the 20 quid for the correctly made fitting that you say is available. If your soldered joint leaks at some point in the future, due to vibration, age, corrosion, not quite soldered right etc, it can drain the cooling system, overheat and totally destroy your engine, costing thousands to repair.  Not worth the risk, to me. Most people don't watch the temperature gauge when they drive so this kind of thing happens more often than you might think.

Edited By Hopper on 05/07/2018 09:15:01

[Brian WoodParticipant @brianwood45127]

I would be tempted to silver solder the two together and then pressure test the joint afterwards. I don't think a soft soldered joint would be good enough.

Regards

Brian

[David George 1Participant @davidgeorge1]

Silver solder will do the job just be carefull clean the joints and use good quality solder and flux.

David

[mechman48Participant @mechman48]

Spend the £20; not worth the risk of engine damage should the joint fail.

​George.

[Keith HaleParticipant @keithhale68713]

Make sure you use a non magnetic steel to a avoid crevice corrosion.
Then use 455 silver solder and HT 5 flux.

[Author]

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