need to descale /clean a brass radiator

[Matchless]

The old radiator from my Jag could do with a clean out, the rad is mostly brass with cast iron top and bottom fittings, the old block and fittings on the rad were well cruddy, looking for thoughts on what I can fill it with to disolve the crud but not the brass! vinegar has been suggested, most modern rads are waffer thin aluminium so I doubt modern radiator flush has much go in it, picture is a spare I bought but my original actually looks to be in better condition!

 

[Seadog]

A domestic radiator cleaner, or phosphoric acid. For best effect, however, you need a circulating pump and a hot solution.

 

[The_Yellow_Ardvark]

Kettle descaller?

 

[Wozzaaah]

Maybe try some Sentinel X400?
As Seadog says, whatever you use really needs to be run through it rather than put in it and let sit.
Saying that, you could temporarily refit the rad, fill the system with X400 and run it for a bit.

 

[RaceDiagnostics]

Merc specify circulating citric acid through their old radiators while still connected to the engine.

I put this much in.

But ended up with this problem.

 

[Brad93]

Keep away from Citrix with any yellow metals. It goes after the zinc!!!

 

[Ross365]

Yes, many reactive chemicals preferentially dissolve the zinc out of brass in a process known as......dezincification!
I'm sure there are chemicals (proprietary products with corrosion inhibitors in them) you can use, but I don't know what they are and suggest extreme caution.

 

[a111r]

Merc specify circulating citric acid through their old radiators while still connected to the engine.

I put this much in.

But ended up with this problem.

I've read the same. That looks a stronger solution than an MB citric sachet!
My old 1983 rad will be replaced after I flush - I just want to clean out the iron block before fitting a new rad..

 

[CompoSimmonite]

I used citric acid to clear a completely blocked Austin A35 rad. I stood it in a bowl and used a small 12v pump running on a battery charger set at 6v to circulate the solution. Left it in the shed for a few days and next time I opened the door it was clean

 

[bricol]

I'd be finding a radiator specialist who could clean and test afterwards - if it fails in the outside lane of a busy motorway, and you don't notice the temp gauge going up then falling again, a rebuilt engine is a lot more expensive than a new rad!

 

[Melvyn Best]

I can recommend Anglia Radiators in Cambridge, an old school radiator specialist ,

 

[The_Yellow_Ardvark]

I can recommend Anglia Radiators in Cambridge, an old school radiator specialist ,

Thumbs up to them as well.

 

[8ob]

Our rad man lets them soak in a caustic solution for a few hours and back flushes them, always mentions that there cant be any guarantee.

Bob

 

[graffian]

They used to hot tank them.

If your using acid a decent washer pump and bucket will probably do to flush it.
Rad cleaner might be OK. We flushed some household rads with the proper stuff
and they still looked ****, we filled them with phosphoric and left them over night,
the next day they looked spotless as far as I could see.

 

[Ross365]

I'm always confused about using phosphoric to clean rusty steel. I thought metal phosphates are insoluble and so form a protective layer on steel. When I've cleaned rusty steel in phosphoric acid, and also the traditional Jenolite proprietary stuff, the steel looked fairly shiny. But with some other products based on phosphoric, including a modern Jenolite product, the surface is sometimes dark blue or black.

And while metal phosphates are supposed be insoluble, the citric acid compounds are definitely soluble . Since I started painting all steel stuff with zinc phosphate primer, I've stopped using phosphoric acid products. I saw some components that seemed to suggest that ZnP paint does not like going on to top of surfaces treated with phosphoric and showed rust blisters after about a year. Phosphoric on brass is something I've never done; sounds iffy to me.

 

[Seadog]

When I've cleaned rusty steel in phosphoric acid, and also the traditional Jenolite proprietary stuff, the steel looked fairly shiny. But with some other products based on phosphoric, including a modern Jenolite product, the surface is sometimes dark blue or black.

Modern Jenolite behaves in exactly the same way as old Jenolite, in that case. I first used it back in the 60s.

 

[Ross365]

Modern Jenolite behaves in exactly the same way as old Jenolite, in that case. I first used it back in the 60s.

Jenolite now have two products; the original stuff is called Rust Remover and the newer stuff is called Rust Converter https://jenolite.com/product-catego...MI09zXoZ3H8QIVBuvtCh01dA3SEAAYASABEgKv5fD_BwE.

The Converter needs to be left on, or re-applied until the surface turns blue/black. I like the original "Remover" but the jury is still out on the Converter.

 

[The_Yellow_Ardvark]

Jenolite now have two products; the original stuff is called Rust Remover and the newer stuff is called Rust Converter https://jenolite.com/product-catego...MI09zXoZ3H8QIVBuvtCh01dA3SEAAYASABEgKv5fD_BwE.

The Converter needs to be left on, or re-applied until the surface turns blue/black. I like the original "Remover" but the jury is still out on the Converter.

Not here.
It is out, left the building, down the pub, 5 beers in and about to grab a pizza.

The new stuff is weak, sad and falls in line with the modern way of treading softly in case any one gets hurt.

Look out for MOD sales, the original stuff does come up in 1lb tubes. But it is getting harder to find as stocks get used and snatched up.

 

[Ross365]

Not here.
It is out, left the building, down the pub, 5 beers in and about to grab a pizza.

The new stuff is weak, sad and falls in line with the modern way of treading softly in case any one gets hurt.

Look out for MOD sales, the original stuff does come up in 1lb tubes. But it is getting harder to find as stocks get used and snatched up.

Yep; that was my impression too.

 

[Mick Annick]

Our rad man lets them soak in a caustic solution for a few hours and back flushes them, always mentions that there cant be any guarantee.

Bob

Bagshot Radiators by any chance? They were our go-to rad people when i was at RMC