Coolant system flushing agents

[IROC-Z]

Can anyone recommend an effective pro grade coolant flushing agent please? There’s lots of on the market i.e. Wynns etc but I’d like something that comes recommended.

I have a 3.0 Essex with overheating issues. I have fitted a new waterpump, new specially made aluminium radiator and a high-power electric cooling fan.

Despite this it still runs up to temperature and gets very hot and bothered quickly, running lumpy and cutting out. The stat is definitely opening, and I can see coolant flowing through the rad. The radiator and top hose get red hot and bottom hose is cool, the fan is shifting a lot of hot air, so it’s doing its job but making no difference to the engine getting too hot.

I am starting to wonder if I have a silted-up block, the car came from South Africa so perhaps 40 years of being driven around in a hot climate with no antifreeze?

[larrylamb11]

In my experience, a central heating system flushing agent is better (and cheaper!) than a proprietary vehicle radiator flushing agent to clean a cooling system. I've used Fernox F8 with good results before on a dry state USA car that came to me with what can only be described as 'mud' in the cooling system....
On heavily corroded systems I've also used straight vinegar .... you can leave that sitting for a while to dissolve internal corrosion and then flush it through - works for heavily corroded systems with alloy and iron components. Cheap catering vinegar in 5L containers is fine.
You may find you have to strip it down until you can get a jet washer straight into some of the block passages and flush it through at high pressure too.

[Lotobear]

Citric acid crystals, dissolved in hot water, works brilliantly - used it several times to clean out water jackets in engine blocks and head castings to great effect.

[IROC-Z]

Thank you both, however do I need to be cautious about using acidic products with my aluminium radiator? Will it just wreck it?

[larrylamb11]

Yes, any acid will attack the metal components, particularly the aluminium and if you're worried about the radiator you should start with a PH neutral cleaner like the central heating flush. From what you've reported though it sounds like you have bigger problems to worry about than the effects on your new radiator.... What is the Essex fitted into? and what was the water like that came out of it when you first started fiddling?

[crankedup5]

My Morris ‘bullnose’ also suffered from overheating problems, eventually I did use one of the coolant flushing agents. It did clear out no end of muck but it also found a hairline crack in the water jacket and further inspections revealed a crack in the block.
I hope you have better luck than I.

[IROC-Z]

larrylamb11 said:

Yes, any acid will attack the metal components, particularly the aluminium and if you're worried about the radiator you should start with a PH neutral cleaner like the central heating flush. From what you've reported though it sounds like you have bigger problems to worry about than the effects on your new radiator.... What is the Essex fitted into? and what was the water like that came out of it when you first started fiddling?

Since my last post I read up on the Fernox F8 and saw that it was PH neutral and safe for all metals - so thank you I will definitely give that a whirl. The engine is in a MKII Granada. I can't remember exactly, but when I first changed the coolant it was most probably a rusty brown colour. Now that I've fitted the new rad the coolant appears to be clean, but I guess if the engine block is furred up then it's not going to necessarily discolour the coolant, just restrict the flow.