Cleaning up a rusty cooling system

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Looks like citric acid is the way to go then.

What baffles me the most is that a year before i bought the car, the then owner put a new radiator in it, and proceeded to fill the cooling system with plain water
21.gif


Mallorca, where i live, is an Island in the middle of the Mediterranian, below freezing temps occur very rarely except up in the mountains.

So a lot of people think it's just fine topping up their cooling systems with just water.
 
Originally Posted by FordCapriDriver
Looks like citric acid is the way to go then.

What baffles me the most is that a year before i bought the car, the then owner put a new radiator in it, and proceeded to fill the cooling system with plain water
21.gif


Mallorca, where i live, is an Island in the middle of the Mediterranian, below freezing temps occur very rarely except up in the mountains.

So a lot of people think it's just fine topping up their cooling systems with just water.

Same with Southern California. They dont realize that coolant contains corrosion inhibitors.
 
Citric acid would be my main choice. Cheap, relatively safe to use and if Mercedes approves of it, it's good enough for me. Degrease the cooling system first with DISHWASHER(not dishwashing) detergent, rinse and then add the acid.

Prestone used to make an oxalic acid-based cleaner with a sodium carbonate neutralizer for hardcore cases of rust and neglect. GM used that in a TSB for Dex-Sludge. It's NLA and I'm not sure about Spain but in the States we can still buy oxalic acid in wood bleach and sodium carbonate is sold at the store as washing soda.
 
In badly abused cooling systems we used CLR and water over multiple flushes. I'm not sure if this would be compatible with modern cooling systems since they have moved to long life coolants though for anyone else reading this...
But it worked well to restore the systems in older vehicles.
 
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Originally Posted by WyrTwister
With a cast iron block and Al head , I would be tempted to just continue doing what you have been doing .

But keep a very close eye on the coolant temps .

Ages ago I used an Oxalic acid product sold by one of the manufacturers of antifreeze . It was a 1966 Mercury Comet with a 289 cast iron V-8 .

https://www.google.com/search?client=firefox-b-1-d&q=oxalic+acid+radiator+cleaner


It really does not overheat, even in the summer with 100°F temps and high humidity, the temp never goes above 1/2 on the gauge.
 
Originally Posted by Chris142
Originally Posted by FordCapriDriver
Looks like citric acid is the way to go then.

What baffles me the most is that a year before i bought the car, the then owner put a new radiator in it, and proceeded to fill the cooling system with plain water
21.gif


Mallorca, where i live, is an Island in the middle of the Mediterranian, below freezing temps occur very rarely except up in the mountains.

So a lot of people think it's just fine topping up their cooling systems with just water.

Same with Southern California. They dont realize that coolant contains corrosion inhibitors.


Exactly, and when i do see people topping up their coolant with coolant and not water, it's usually the wrong coolant, or a really diluted premix coolant, here in Spain commonly you can even find 10% glycol premix coolants.

The other day i saw some lady putting what seemed like conventional green coolant, into a new-ish Toyota... for example
 
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Since it's not causing any problems....I would just leave it. And use a good quality Antifreeze since they have better rust inhibitors than AMAM's.
 
Originally Posted by Warstud
Since it's not causing any problems....I would just leave it. And use a good quality Antifreeze since they have better rust inhibitors than AMAM's.



I have been using what is sold in the U.S as Zerex G40, a Sillicate HOAT with no 2-Eha
smile.gif
 
I dealt with a similar issue a couple years ago and tried almost every method that has been mentioned so far with mixed results. What ended up being the best method BY FAR was to fill the entire engine (I did not fill the radiator, but you could if you wanted to) with Evaporust and letting it set a few days before draining.
 
I would just put a modern coolant in it and leave it alone. You start getting rid of the rust and there will be problems - a flake of rust off that frost plug, and now it will leak. Same with the head gasket, pull too much debris from around it and it'll be week. So, so many problems after rusty cooling system flushes.
 
Originally Posted by thescreensavers
Remove the thermostat and run Citric Acid mixture in or try thermocure.

I did citric acid flush in my Jeep and the water turned pitch black, it required lots of post flushing.

https://i.imgur.com/CoexCKL.gifv over about 30 min



Pitch black.. You weren't kidding. Wow.

I did a citric acid flush on my truck last summer. I had just replaced the heater core so I bypassed it and ran the truck for about 20-30 minutes at idle with no thermostat. Rust chunks fell out when I removed the block plugs. The radiator and water pump ended up living through the process and have been fine since.
 
Unless you plan on doing the radiator separately and not running cleaning stuff through the entire engine, I'd probably look at it like a transmission that hasn't ever had the fluid changed in 200,000 miles, and so people often do limited drain-and-fills instead of full fluid replacement, and certainly not pressurized full fluid replacement. If you try to dislodge too much at once, big particles might cause problems.

That's less likely for coolant passages than automatic transmission passages, but the concept is the same. Or like using a cleaning detergent for caked-on oil to try to clean the internal of an engine all at once, instead of just doing more typical oil changes to let the internals get clean gradually.

Also, cleaning out the reservoir tank every three months seems to be a pretty good and gradual way of getting the rust out of there. It's like emptying an oil catch-can, but for antifreeze. haha
 
Similar neglect on my van on part of the previous owner. The van's also from a temperature climate, CA. How do people get away with neglecting a car for so long? I ended replacing all the main hoses, and even the engine itself. I was worried the rust had compromised the head gasket too much, and decided to put in a used engine instead of replacing the gasket. That was 2 years ago.
 
Similar neglect on my van on part of the previous owner. The van's also from a temperature climate, CA. How do people get away with neglecting a car for so long? I ended replacing all the main hoses, and even the engine itself. I was worried the rust had compromised the head gasket too much, and decided to put in a used engine instead of replacing the gasket. That was 2 years ago.
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Originally Posted by FordCapriDriver
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?


I was under the impression that everything was still original and if you did mentioned earlier that thosen items were changed, I misses it. And though the rad isn't showing any problems, it just doesn't look healthy. That's the only reason I mentioned changing it.

Best of luck and keep us posted.
 
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