Need help--How to Clean Radiator

[BLB27]

I have removed the radiator from my 1927 coupe. The coupe hasn't been run since 1959. How do I clean out the inside of the radiator?

[John iaccino]

Plug the outlet and pour in cheap vinegar and let it stand for a few hours. Put the radiator back on the car and fill with water mixed with washing soda. Let the car run until it gets hot , then drain. When all finished, fill with water to neutralize the vinegar and washing soda. An old trick told to me by an old radiator man.

[Humblej]

Take it to a radiator repair shop, they can clean it, test for leaks, and repair as needed.

[D Stroud]

Make sure the radiator shop understands that it is not a pressurised system. If they test it with anything much over 2 or 3 PSI, they may well destroy it. Just ask Dallas. Dave

[John kuehn]

Hopefully the radiator will still do it’s job of cooling. If it’s an original radiator be prepared that it may not cool well. Being cleaned up and still looking good is not a guarantee that it will still cool well. Good luck.

[John Codman]

I agree with John Kuehn. I found this out the hard way.

[Steve Jelf]

What John and John are talking about is the fact that many decades of vibration can cause the radiator's cooling fins to work loose from the tubes. With that decreased physical contact not enough heat is transferred from the tubes to the fins to the air, so the radiator no longer radiates as it should.

http://dauntlessgeezer.com/DG96.html

[HPetrino]

If it hasn't been run in 61 years I'd also pull the head and clean both the block and the head at the same time.

[Norman Kling]

Here is a way NOT to clean it. Many years ago I had a Model A. I wanted to clean the radiator and a poured in some laundry detergent and water and ran the engine for a while. Then I drained it out. I flushed it over and over and then went for a ride. It was like Lawrence Welk's bubble machine. It took a very long time to get it to stop foaming. I think your vinegar and soda method is a good one. The vinegar will dissolve hard water deposits and rust. The soda will neutralize the vinegar and it should help. However, a radiator shop can do a better job, and if it is a good shop will also fix any leaks and tell you whether the radiator can be used again.
The main problem with old radiators is corrosion in the junction with the cross fins and the water tubes which inhibits heat transfer and cooling. So even if the tubes are clean and not leaking, it will still not cool the engine.
Norm