Barely leaking radiator core issue

[John kuehn]

I was looking at my 21 Touring today and noticed the replacement flat tube radiator has a couple of damp spots on it and very small leaks. These are very slow and not dripping. The radiator was a flat tube recore bought on eBay years ago when I was assembling parts to build the 21. I haven’t use any radiator stop leak in any of my cars for years.
Yes I know the best way is to remove the radiator and either pinch off the leak area or solder it.
Before I resort to doing that any recommendations would be appreciated for a pour in stop leak would be appreciated.
Thanks

[Jack Putnam, in Ohio]

alumaseal radiator sealent is the best available. Hard to find. It is a powder and will work in the thermal circulation of the T. The last i bought came from ebay.

[Allan]

If you are using coolant/antifreeze, that will find the smallest of faults and leak. Perhaps it should be called leak finder. A change to water and some soluble oil may make the "leaks" go away. Others will have different ideas.

Allan from down under.

[speedytinc]

"egg keep" sodium silicate aka Water glass. Had success with this stuff.
I would go with Allan's recommendation first.

[Craig Leach]

I have had good results with a product called K Seal.
Craig.

[John kuehn]

Thanks for the tips. I may change the radiator coolant. I have antifreeze in it since the shop isn’t heated for winter. Maybe I should use less antifreeze in it. It’s got over 1/2 antifreeze in it. We dont get long weeks of below freezing in central Texas. Maybe 1/4 antifreeze and the rest water might do. Since the shop is enclosed and out of the wind and weather hat be enough even really cold. But I will get one of the radiator sealants mentioned.
Any thoughts about using a weakened radiator coolant? In other words not much antifreeze?.?

[speedytinc]

I believe any antifreeze will find a way to leak as Allan says. I run water & water soluble oil. But, I never see temps below 40 where I am.

[John.Zibell]

Thanks for the tips. I may change the radiator coolant. I have antifreeze in it since the shop isn’t heated for winter. Maybe I should use less antifreeze in it. It’s got over 1/2 antifreeze in it. We dont get long weeks of below freezing in central Texas. Maybe 1/4 antifreeze and the rest water might do. Since the shop is enclosed and out of the wind and weather hat be enough even really cold. But I will get one of the radiator sealants mentioned.
Any thoughts about using a weakened radiator coolant? In other words not much antifreeze?.?

John, antifreeze can be mixed to give protection down to specified temperatures. I do believe a 50/50 mix is ideal but the ration can be changed to provide protection to designated freezing points. I would recommend mixing for a temperature at least 20 degrees colder than you usually observe in the winter. Better option may be to just take the radiator to a shop and have the leaks soldered.

[TXGOAT2]

You'd probably be OK with a 40/60 mix of antifreeze and water. But.... Texas weather can be unpredictable...

[Professor Fate]

Anyone ever try black pepper? A few tablespoons? Radiator
Shop says use pepper! Also, the bars leak tabs have
always gotten me home.

[Dennis Prince]

An old radiator man told me to use ground ginger, I have used it on many vehicles and it always works. Those seal tabs that come with a new GM water pump are ground ginger, I some times find it at the Dollar Store, I use about 1/2 a jar (about 3 1/2 in tall) for a T. Put it in a hot engine and dissolve it in a cup of hot water before adding and then drive for a while.