How do you flush an old radiator?

I've got the old radiator from my 50 Chevy sedan, and I'm planning on continuing to use it on the 283 SBC that I installed. However, when I originally took it off when the 216 was in there, it drained slowly. I know it's got crud in there somewhere...but since it's currently off of the engine, what's the best way to flush it out?

Thanks!

 

vinegar and water mix. seal it up and let it sit for a few days.flush it out.

 

They also sell some radiator flush at the part store. You pour it in then start it up and let it run for 20 minutes then drain. I don't know if it works better than vinegar but it works.

 

Sealed power, you are right. But I learned the hard way NOT to leave it in there too long. We guys hate reading directions, but . . . LOL

 

Use a mix of 50% water and 50% Muriatic acid. Let it sit for 30 minutes and then flush with water until it runs clear. If its still plugged do it again. The acid works well but don't get carried away or you'll burn through the tubes!!

The Old Tinbasher

 

I was going to say Muratic,,it's cheap ,,just be careful. Don't forget to turn off the disolving properties by flushing it with baking soda water.

 

That's funny... the guys at the part store made it a point to tell that.


They had a guy come in raising hell. He put the stuff in the radiator and left it. Drove it around for two or three days with it there before it finally ate the radiator completely.

Read the directions and do not leave it in the radiator.

 

And don't leave muriatic laying around the garage. The vapors will rust anything in the area.

 

Notice a trend? Either use a professional acidic flush product, or acidic vinegar, or a jug of acid.

I'll add another tip, the reaction is time/temp/concentration dependent. Upping any one will lower the other two so use hot water, but be careful with overnight soaks in winter! Good luck

 

I would just take it to a honest radiator shop, they can boil it flush it and flow and pressure check it. Where i live its about 50 bucks Takes all the guess work out of it
My two cents

 

Was it cooling the 216 ok? If it was you could leave it alone unit you get the v-8 done and then flush it. Or take it to a radiator shop and get it flushed. I grew up right near where you live. I'll bet there is ALOT of radiator shops near you. Todd

 

X2

I paid 60 bucks to have mine flushed, rodded (spelling?) and pressure tested. They re-soldered the top tank and a few pin holes where it was leaking....

 

I think i would get it hot tanked..save yourself the headaches..and an over heated SBC

 

Take it to a radiator shop,in the long run you be glad you did,dont half ass it,it dosent cost that much

 

I talked to a guy up at the Chickashea Pre War swap last year who told me to cap one end tight, put a box of dishwashing detergent in.

(The powder not the liquid. The powder doesn't sud up)

Fill it up with water and close it off. Put the radiator in the back of your car or truck and leave it there for a week or two as you drive your car.

Drain it and rinse it out. Done.

He even said that if you want to clean the radiator and engine while it is still in the car just add the powder and drive the car. According to him it won't hurt anything and will clean all the water passeges in the engine. It is even safe for brass era radiators.

To get it all out just drain the radiator and fill with water. Drive it for a few days then repeat till clean.


I did it and it works.

 

I pulled out my thermostat and filled my cooling system (307/stock radiator) in my 1957 Chevy truck with straight vinegar. I ran it for a day, then drained it. Came out black. Filled it with water, ran it for another day, then drained it. Came out black again. Repeated the water and draining thing until it stopped coming out black. Then added a teaspoon of baking soda and ran it that way ever since. The damn thing won't even come up to 150 degrees now, I need to add a thermostat.

 

I would let a professional radiator shop flush and clean the radiator . They will also pressure test and flow check the radiator to make sure it is 100% ready to use . I think that would be the best way to go .

RetroJim

 

The radiator shop MAY be the answer, may not. Around here, it is difficult to find a shop that still has the old fashioned dip tank. Too many regs (sewer related) and effluent testing required. They simply back flush with a combination of cold water and compressed air. That produces an effluent they can discharge without testing or treatment. The local guy told me it does a pretty good job on about 75% of the radiators they service. The other 25% are either recored or junked.

Bill

 

The dishwasher powder soap (cascade) trick works better on the oil in the system. If it is out take it to a shop.

 

Last time I flushed a radiator ,It took 2 days for the plumber to get it fixed.Sorry I couldn't resist.

 

THANKS for all the info ya'll!!!

It seemed to be cooling it ok, although after it ran for awhile there was always a little steam coming out of the valve cover. I do know that it has some plugging up going on. I'll check around and see what I can find in the way of shops that will do it. So I can just take the radiator in separately and they can do that? I suppose it will also tell whether or not it's still any good...I hope so....otherwise $$$$.

 

Now that was funny...

 

Has anyone tried that CLR stuff, It' supposed to remove calcium lime and rust?

 

You beat me to it lol

 

I did the Muriatic acid in a radiator for about 3 hours (good half gallon).It didnt seem like it was working.Well it burned through the tubes like said before.Becareful.

 

I did the muriatic thing on my 68 impala . here in cali we have really hard water so the car was overheating cuz the radiator was full of calcium/mineral deposits . I poured in over a half gallon of acid and then filled to the top with water and let sit for 30 minutes .. Sunnofabee that radiator was bright pink inside after that . that was in 1997 and two motors ago and its still going fine .. PS i been using distilled water in it the whole time ..

 

Muriatic acid (hydrocloric acid) will eat away corrosion AND metal...as will battery acid (sulfuric acid), and nitric acid. Phosphoric acid (Navel Jelly, CLR, etc)will not eat away metal, only the corrosion..EXCEPT for aluminum. I use a lot of phosphoric acid for rust removal, corrosion removal, etc., on iron, steel, copper and brass. I get mine at the local Tractor Supply (Farm and Home, etc). It's called "Milk Stone Remover And Acid Rinse" and is used by Dairy farmers to rinse the inside of their stainless steel milk holding tanks, to remove calcium film. It comes in 1 gallon plastic bottles and runs about $12-$13 a gallon. I've used it to remove the crap in radiators, with great results...among other uses. It dissolves everything, but leaves the metal. Using Muriatic acid is a crap shoot, since the time necessary to dissolve the deposits, and the time necessary to eat up the metal is real tricky...

 

Oxalic acid is, from my understanding, what the "old" radiator flush solution used to be made of. Not sure if it is still an ingredient, but you can buy it in a hardware store. It's called wood bleach.

 

Best way is in the summertime, so it won't freeze up. Remove the thermostat, Drain, add radiator flush and water. Drive it a couple of hours. Drain, fill with water, run a little while and drain again.

Could be done in winter if you are familiar with the drill, block the radiator to keep it from freezing up, adjust the blocking device to prevent it from overheating.

 

I had this happening to me on my 235. I was told that it was moisture exaporating out of the oil/crankcase. Not sure if that's true or not...but it really spooked me the first time I saw it, I thought I had burned up the engine.