Rusty Coolant
 

Just what it says, I have rusty coolant. I have tried the vinegar trick, I have flushed, flushed again... Vinegar actually caused leaks from my experience. My Dad always ran water because he said antifreeze creeps in places water can’t (smaller molecules).

The engine is only a few years old on a rebuild where it was extensively cleaned out. The radiator was replaced after the vinegar experiment and subsequent leaks. But it’s still rusty.
What do you do to stop the rust? Is there an additive? Do I run antifreeze instead?

Re: Rusty Coolant
 

If you want to run straight water, you need to add a bottle or two of "Anti-Rust & Water Pump Lubricant". This stuff is getting harder to find because everyone runs antifreeze in modern cars now. NAPA used to carry it. Also, light grease the water pump fitting closest to the engine, even if you have a modern seal.

Re: Rusty Coolant
 

Stop the rust !!!! Rust 911, Evaporust are two good choices ! Vinegar is an acid, if after its use you need to neutralize the acid ! or the vinegar will let the metals to continue rusting.

Using water only is just not right, additives are need to keep the metals from rusting.

Re: Rusty Coolant
 

Buy yourself some Thermocure, it's made by Evaporust and meant for exactly your situation. Follow the instructions and you'll be amazed at how well it works. If it's really bad it might take two uses. I used it and the to tank of my radiator went from a rusty mess to clean shiny brass.

Once the rust it out I would use antifreeze but if you don't need the freeze protection do as Jim says. Your dad was right about antifreeze, on water my original petcock doesn't leak, on antifreeze it has a very slow drip.

I used to buy bottles made by Gunk, it was a white liquid. Can't find it anymore though.

Re: Rusty Coolant
 

Additive - https://www.napaonline.com/en/p/MCC1300

If using water, use distilled water.

Even though distilled water/additive cools the best, green antifreeze keeps the rust away better than water with additive.

If converting from one type of antifreeze to another, cooling system must be thoroughly back-flush/flush out the old antifreeze before putting in a different type. Never mix antifreeze types. This is advice I've received from multiple professional mechanics including those who work on As and classic/antique cars.

Use green antifreeze, some of the more modern antifreeze types can eat away at solder.

If using white vinegar, do a final flush of baking soda/water to neutralize remnants of the vinegar that seeps into the metal. As mentioned above, the acidic content can continue to slowly over time eat away at tthe cooling system. An analogy is what happens to metal battery holders if not occasionally wiped down with baking soda/water.

Rust 911/Thermocure are not acidic, do not damage metal/rubber, only "dissolves" rust. It is important to 1st do a treatment of detergent (Dawn, etc) to flush out grease /oil. Thermocure/Rust 911 does not remove oil/grease, so any rust under the grease/oil is not affected/treated by the rust911/thermocure treatment.



Leave the rust 911/thermocure treatment in and drive the A every day for a week, then drain. Depending how much rust is in the cooling system, you may have to do more than one treatment.

If your radiator is very old and in poor shape, treatments may cause leaks from the removal of rust acting as a plug that was keeping it from leaking. This seems to happen more when using an aggressive acid treatment like white vinegar.

When done, install an upper hose coolant filter, to protect your clean radiator from further crud from getting into the radiator.

Re: Rusty Coolant
 

Either use Water Wetter or use ethylene glycol like everyone else does. Some die hard "water only" individuals find that they have to use the Water Wetter due to the corrosion that happens with no corrosion preventative in the cooling system. There is a negligible difference in how much heat is transferred between plain water and anti-freeze. If the system leaks then it's going to overheat no matter what is in there.

Re: Rusty Coolant
 

A last warning - using acidic treatments like white vinegar may flush/remote the grease in the water pump packing nut that helps seal the water pump shaft. The cooling fan will blow hot rusty water/vinegar through the motor bay and out through the hood louvers. A real mess that also can ruin your paint. I've seen pictures, and it is not pleasant.

Re: Rusty Coolant
 

Have been told or read somewhere that a true rust inhibitor such as MACs 1300 is much better as a rust inhibitor than Waterwetter. Sorry, can not find the info and back up my belief.

Re: Rusty Coolant
 

Preston anti rust inhibitor, Amazon $5.00. NAPA around here has there own brand of rust inhibitor, about the same price.

I have always used just regular water with rust inhibitor. Water cools better than anti-freeze, if it gets into your oil, water does not have same effect as anti-freeze, less leaking problems with water. I have tried distilled water, but even with using rust inhibitor, water was very rusty when drained.

This, like what motor oil should you use, everyone has a view.

Enjoy.

Re: Rusty Coolant
 

My car has always had rusty water, even before it's light restoration in the early 80's. After it's 30 year hiatus my Dad put it in without draining fluids, I completely flushed it before starting in 2016 and use distilled water and green antifreeze with some rust inhibitor. Rust is still present but does not overheat like it did with straight water. Every winter I drain it too. But since it seems to be a non-issue I just run it.

Re: Rusty Coolant
 

I've seen this stated numerous times on this and other forums. I just don't see it happening but if so what diameter hole does one need to put in a container of a 50/50 mix to separate the coolant back out of the water?

Re: Rusty Coolant
 

For 28 years I have used only tap water in my 1929 RPU radiator, without any sign of rust (and no cooling problems either). I know this sounds strange, but it is true. I put this down to either the quality of the water, or the fact that I occasionally tighten up the grease cap on the water pump which pushes a little water-soluble grease into it. Last time I took the radiator hose off and looked inside, there was a slimy, greasy film on it that (I assume) is protecting it from rust.

Re: Rusty Coolant
 

If you use Water and Water Wetter, it will not prevent rust. You need to use an anti-rust product.

Re: Rusty Coolant
 

Plain demineralized water will absorb heat more but that leads to the lower boiling point as well. Ethylene glycol mix will boil at a higher temperature than water. This makes the cooling capability moot on an engine that runs on the verge of overtemp due to air leaks, thin cylinder walls, and the possibility of a fair amount of crud build up in the tubes of the radiator.

Run water if you want but there is no advantage to it and you have to drain it anytime it freezes.

Re: Rusty Coolant
 

You put plain water in a cast iron block and are surprised you have rusty water now? Use 50/50 antifreeze.

Re: Rusty Coolant
 

Re: Rusty Coolant
 

Where did I say I was surprised?

Re: Rusty Coolant
 

I used to use that too - still have a bottle or two around somewhere. I stopped using it when I found that it was just like any other anti rust/ lubricant additive I had seen up till then. It attacks the hoses and makes them swell and go mushy. I now use another american product called "Motor Medic" made by Niteo Products LLC. It is added to the cooling system in addition to your usual coolant. No effect on hoses and lasts forever.