Flushing the cooling system

[Mr Spigot]

I have recently had some small repairs carried out on the radiator (large header tank) of my 1952 side valve convertible. When it was removed I flushed it through with a hose in both directions until the water ran clear. It was quite brown initially and some lumps of brown sludge came out. I also flushed the engine through with the hose with a similar result. Now the radiator has been replaced and all the hoses connected, it seems a good opportunity to flush it all through again and wondered if anyone had any recommendations for a good flushing product?

[oliver90owner]

Water.

[geoberni]

If you're only flushing it, then just water .
If you want to try and clean it a bit, let it stand for a day with some citric acid crystals solution.

[Mr Spigot]

Thanks. Perhaps I should have worded my request more clearly. It has already been flushed out with water and I know that there are products to carry out some cleaning of the insides and remove any residual sludge. It is these that I would appreciate some guidance on. Presumably a citric acid solution will not harm gaskets or seals?

[geoberni]

I first used Citric Acid after this discussion back in 2017. Cleaned a lot of crud from my car's cooling system without any harm.
viewtopic.php?t=66854

[Mr Spigot]

Thanks. The old thread is very helpful.

[Bill_qaz]

Dishwasher tablets