How to Get Rust Out of Cooling System

Whats the best way to clean out the cooling system in a 1950 cad?
Ive hosed it out several times, but it still runs hot, and the coolant eventually shows rust particles in it.

Any product/methods work well for you guys?
for a start try prestone cooling system cleaner... run it for a few days as per instructions. seemed to clean out the gunky coolant in my 89 burb.
I've used Oxalic acid, commonly sold as Wood Bleach and have had great results. Drain & flush mix up the Wood Bleach (it comes in crystal form) with some water, pour it in and re-fill. You can leave it in for a few days and let it circulate through the cooling system. The Oxalic Acid will only attack the rust. It wasn't the easiest thing to find, I had to go to an old time hardware store to get it, the places like Home Cheapo had no idea what I was talking about. Here's another thread right here on the HAMB about the stuff.
Back in the day,the DuPont #7 radiator flush contained the same ingredient and had the cleaner in crystal form in the bottom and a neutralizer in the top of the can.The PC police screwed that up for us.
You might try a little vinegar mixed in with the water. Maybe a half and half mix.
You can fill it with white vinegar,run several days drain&flush.Repeat as needed,works.Some use baking soda and water mixture to neutralize.
Thanks for the replies guys. I have a bottle of prestone coolant flush lying around that I havent used yet. I suspect it wont be strong enough but might as well use it first. Then onto the next.
I've used a gallon of white vinegar mixed with water. Continue to drive for a week or so, then flush again. You may need to repeat this several times, depending on the cooling system condition. Don't bother with parts store cleaning remedies, our friends at the EPA have made them just a tad harsher than mouthwash.
---John
Only thing is, it tends to run hot so i dont really drive it much. I think theres a lot of crud in the water passages
Heat always helps a chemical reaction, but in your case of overheating, I don't think you really need to drive it, just warm it up to get the mix into all the nooks and crannies. Maybe idle for 5 minutes every couple of hours.
One thing to be aware of is if there is that much rusting going on in your cooling system, it could be the fins have rusted off the water pump impeller. Check the flow out of the top radiator hose into the radiator when the engine is warmed up so the thermostat is open.
Interesting that a search shows the 12 ounce container selling for under $6 at most stores but Walmart lists it at $27.77, marked down from $31.47.
@Wolfcreek-Steve the original pump failed so ive replaced it. Thermostat was removed to aid in flow for now
Keep in mind that the rust chunks can clog the radiator!! Pete
Professional cooling system de-scaling is done with Sulphamic acid for hard water, lime and antifreeze build up.
Oxalic acid is used to remove rust.
Sulphamic acid crystals are available at the hardware store in form of 'grout and tile cleaner'.
Oxalic acid crystals are available in form of 'wood bleach'.
Containers say what acid is used and its pure acid crystals with no other additives.
Available in 16oz. containers, which gives the right mixing ratio with water for the typical car cooling system with 3-4 gallons capacity.
Properly diluted, both acids are just as mild and safe as vinegar (acetic acid) and citric acid, but are more effective and cost is the same.
These treatments are safe to use with copper/brass radiators.
It is supposed to be safe with aluminum radiators as well, but I would do some tests first to determine how much reaction time is actually safe.

Oxalic acid used to be sold as a heavy duty 2-part cooling system cleaner over the counter until a few years ago by Prestone. Recommendation said to do this annually...

For best results it's essential to keep temperature at engine operating temp and to keep the flow going.
Instructions are to drain and flush first, then fill with the diluted acid mix and run the engine at fast idle or drive for 3 hours.
Do one acid treatment at a time, starting with the sulphamic acid, then drain and flush, followed by oxalic acid, then drain and flush.
The final step is to neutralize any remaining acid with a mix of washing soda and water and run the engine again for a while, then drain and flush and finally fill with coolant, but using distilled water instead of tap water, this time.

These methods really work exceptionally well.
I did both, back to back, on my old engine that had serious scale and rust build up.
Before the treatments and despite a new 3 core radiator, coolant temps easily climbed above 180 during the hot summer months with harder use.
After the treatments, the same engine now needs the thermostat to even get up to 180 degrees, even in the summer.
I forgot to add put some old panty hose on the return line to the radiator to catch crap that can clog it up.Not sure about driving too much with out checking for build-up.
Will that ruin my panty hose? LOL
Use the wife's.Don't buy new,getcha in hot water.
You may have the same thing going on I had in a 55 Buick I had.... block was full of "mud" and rust. I pulled all of the freeze plugs and broke the mud loose (used a coat hander to dig around) while running a garden hose into the upper radiator hose (remove thermostat first). You will get wet and dirty !!! Once the mud is cleaned out, refil with the above treatments and I bet it will run as cool as a cucumber
That would be great. Never removed/installed freeze plugs before. Is it hard to do? Do i need to remove anything to access them?
Not sure if it's a good idea, but I have on a couple OT cars. The worst one had a plugged heater core. I'd flush it and it would work for only a few days. I had a spare submersible pump that I put in a bucket of water with the CLR. Hooked the output to one heater hose and ran another hose back to the bucket for a return. I let it run for a couple hours. I flushed the whole cooling system as well as just flushing the core.
After I did that it's been working great for months and months. Was an easy fix for a very expensive heater core.
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Cascade dishwashing detergent works great and is not harmful to anything. Just pour a bunch in the radiator, put the cap back on, and run it for a while to let it circulate. Then take off the lower hose to drain it. Refill it with plain water and run it again, if it still looks rusty, repeat the Cascade treatment.
Caterpillar puts a box of Cascade in the box with new/rebuilt oil coolers for their engines, so if they recommend using it, you know it works.
Years ago a friend had an old pressure flusher and I built my own patterned from it, worked really good to flush all the rust and scale. Basically a section of 2 " pipe, one end open to hook to the top radiator hose going into the engine. You need to remove the T-stat. The other end of the pipe had a place for a garden hose (with a check valve) and then a place for air in front of that with a blow gun type valve. Let the water run until it's coming out the top of the radiator and give the air a good blast, repeat until no more rust and crap comes out. It is a good idea to block the heater because I've popped a couple heater cores on chevys.
Acid flush is good but IMO, the pressure flush is the only way to get all that settled scaled out of the water jackets.
Will the the chemical cleaners mentioned in the
earlier posts be harmful to an aluminum radiator?
Years ago, before the EPA took complete control of our lives, we used Trichlorethylene. Just pour a quart in the radiator, run the engine for half an hour or so. Drain and flush real good. The problem with the trichlor was that if you left it in the cooling system too long, it'd eat the gaskets right out of your engine.
Also used it for cleaning engine blocks before rebuilding. In a commercial degreaser at a place where I worked, I'd put a Model B engine block in the basket and run it through the machine. All grease, rust and paint would be removed. Blocks looked like they just came fresh from the foundry.
I have and oldtimer buddy who has the same flusher. That thing will peel paint if ya pour the coal to it! Very effective, & you can blow a heater core like a pop can if you're not careful. ( as you warned, block it out)
Replacement of soft plugs is much better done with the engine out of the car. My dad had a 390 Ford that ran hot so before a trip to Alaska he replaced the soft plugs and found that the block still had core sand from the casting of the block in it. So he scratched it out with a stiff wire and flushed it out. That was the end of overheating.
had excellent results in a 73 Formula 400 Pontiac with Thermocure from Evaporust. system was overheating terribly and full of rust. Thermocure totally got rid of it. Installed a flowkooler pump, 50/50 mix and a bottle of hyperkhul to prevent any more corrosion or issues with the aluminum radiator. about to do the same treatment to my 91 Olds Custom Cruiser.

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How to Get Rust Out of Cooling System

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Cheeke Treas1959

How to Get Rust Out of Cooling System

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