Cleaning up a rusty cooling system

[FCD]

have had my 1988 Escort XR3i Cabrio for just over a year now.

The previous owner/s neglected the cooling system badly, it had no trace of coolant in the cooling system, just brown rusty water when i bought it.

I have by now flushed the coolant about 5 times ( just drain and fill )

Before, the fresh coolant would turn brown again shortly after changing it because of the rust.

Now the coolant stays clean, however i have to clean out the expansion tank every few months because it keeps accumulating rust at the bottom, i changed one of the hoses in December and found the inside of the old hose, and the inside of the thermostat housing still completely caked in rust ( cast iron block, Alu cylinder head )

Despite all this the engine has no cooling problems, leaks or anything else, it's just really rusty inside.

What generic type of product would you recommend to clean out the rust?

I live in Spain so it's pointless to recommend a particular brand or product, because i won't be able to get it here.

Vinegar?
Citric Acid?
De-scaler??

2019-03-01_10-18-11 by Argentum Enim in Sempiternum, en Flickr

 

[CharBaby]

Ooooh, that's bad!
I wouldn't even know where to begin with that. By the time you get all the rust cleaned out, it may end up leaking.
I may just get a new radiator, water pump & heater core and all new hoses too.

 

[demarpaint]

I would try Citric Acid, but I have my doubts. That cooling system is bad. No leaks now can turn into a nightmare real fast in that system.

 

[joegreen]

Citric acid

 

[Snagglefoot]

There are radiator flush products that might help.

 

[Kestas]

Citric acid. It's available on auto store shelves. Follow directions.

 

[Chris142]

The chunks of rust will be in the bottom of the water jackets. You need to get that out. Pull a freeze plug?

 

[BigD1]

Never have used Thermocure by Evapo-Rust, but I would try it if I had one rusted like that.

https://evapo-rust.com/thermocure/

 

[Donald]

How about a coolant filter on one of the heater hoses?

 

[Trav]

Originally Posted by demarpaint
I would try Citric Acid, but I have my doubts. That cooling system is bad. No leaks now can turn into a nightmare real fast in that system.


+1 Citric acid will clean that right up.

 

[Astro14]

The principal ingredient in Naval Jelly is phosphoric acid (also found in many sodas, which is why soaking old bolts in Coke removes rust...). So, the citric acid recommendation is spot-on. It will dissolve the rust from the surfaces you show. Phosphoric acid may be too much for your aluminum head. Stick with the Citric.

Now, will one treatment work? As the rust dissolves, the acid gets weaker and weaker, until it's neutral Ph (chemists, feel free to weigh in here if I'm incorrect). If you've got a bunch of rust stuck in the bottom of the block cooling passages, for example, I could see needing a couple of citric acid flushes as it will take a lot of acid to dissolve all of that rust.

Your expansion tank accumulation tells me that you've still got a lot of rust in your system.

 

[dlundblad]

Start with citric acid to expose potential issues and go from there.

 

[krismoriah72]

A gallon of white vinegar then top off with distilled water. Its like an acid wash.. it will remove just about everything. Be careful around aluminum it eats it.

 

[FCD]

Originally Posted by Char Baby
Ooooh, that's bad!
I wouldn't even know where to begin with that. By the time you get all the rust cleaned out, it may end up leaking.
I may just get a new radiator, water pump & heater core and all new hoses too.


The water pump was changed in July last year along with the whole timing belt kit, and i changed the upper radiator hose in December.
However the radiator and heater core aren't showing any problems, why would i change them?

 

[Astro14]

Originally Posted by krismoriah72
A gallon of white vinegar then top off with distilled water. Its like an acid wash.. it will remove just about everything. Be careful around aluminum it eats it.



So, with aluminum heads, he should???

 

[FCD]

As i said despite the previous neglect, the coolant at least stays clean now, and it has no cooling problems.

I have had some people tell me to just leave it alone if it's not showing any problems.

 

[FCD]

Most people i've asked suggest either citric acid or white vinegar.

However i don't want to use anything that's really corrosive to aluminium as the cylinder head and radiator are alu.

 

[Rand]

citric acid is the normal radiator super flush type product.

I would run that according to its directions the next time you want to replace your coolant.

you can premix generic citric acid for the same result.

https://www.amazon.com/Prestone-AS107-Super-Radiator-Flush/dp/B000BPSVWI

 

[FCD]

Would the rust in the cooling system cause the coolant to degrade faster than normal, turn acidic faster?

 

[kschachn]

No, oxides are generally insoluble. But it sure isn't going to do much good for the water pump impeller. It can also jam the thermostat if the pieces are big enough plus clog the radiator of course.