Foam in Radiator

John in Zebulon NC

John in Zebulon NC

Member
What may be the probable cause for foam/small bubbles in the radiator? There does not appear to be any oil in the radiator, or water in the oil, so any thoughts or suggestions will be helpful. Thanks.
 
John foam is caused from anti-freeze and low water. You need a working 4 lb pressure cap or Skips 3 lb pressure valve if the radiator is not set up for a pressure cap. For a pressure cap the over flow tube has to come from the filler neck. Fill the radiator up to within 2"s from the very top of the radiator tank. This will allow for a slight amount expansion of the coolant and the hoses will take the rest leaving no room for air. Bubbles are a differant story, they come from a compression leak. Fill the radiator up so the water is up in the neck, the top of the water can't be down below the neck or you won't know if you have bubbles or foam. With the water up in the neck and the cap OFF run the engine at a fast idle watching the water for bubbles. With a compression leak the hotter the water gets the larger the bubbles. They start out less than 1/8" and when it gets up in the 228 range are about 3/4" just before it blows about a gallon out the neck. Bubbles less then 1/4" can usually be stopped with a good sealer. To locate the side of the engine with a bad head gasket or crack remove the fan belt and upper radiator hoses. Put 2 short hoses on the heads or water pumps and put water in so it comes up in the short hoses where you can see it. Start the engine and run 3 or 4 minutes and the side with the bubbles is the side with the problem. G.M.
 
Most old Fords have small leaks and I use a bottle of Barrs heavy duty alluminum sealer in every engine. This is a fairly large bottle with clear liquid and aluminum flakes. The aluminum flakes combined with Skips high volume pumps clean the radiator tubes and plates like a light sand blasting or more like polishing. This take a while but it works. Attached is a photo of the plate and tubes in my 39 after 15 or 20 years. It is hard to get a good picture down in the radiator. There are also some block sealers for cracks but I never used them. G.M.
 

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I will have to look for the bars aluminum,Ive use the bars that looks like molassis with rat turds in the bottom,Ihave also used the ceramic[water glass]type.
 
GM, I had no idea that Bars leak sealer would do such a great job of keeping a radiator that clean besides sealing small leaks , good info. thanks Harold ,central coast Ca.
 
John, I suggest that there is another (possible) cause of foam in the radiator tank, i.e., if you are using a mix of water and antifreeze. Some of us have found that a mix of the green-type antifreeze with water tends to foam at normal operating temperature in combination with moderate engine speed. In my experience, the foam came out the over flow tube as if I had a compression leak. This was true even with a coolant volume that was two inches below the outlet at start-up. When I posted my observations on the old FordBarn site, the advice was to drain the system and use 1) only water, plus a rust inhibitor, or 2) the orange type antifreeze (dex cool, I think) plus water. With either coolant, the problem was solved. No more foaming.

Richard
 
Thanks Guys for all of the info and wisdom from your experience. This is what makes Fordbarn such a valuable resource for us all. I will try the Bars and then some orange anti-freeze. Thanks.
 
Another possible cause is, that if you ever used detergent to clean out your system, it takes FOREVER to rinse out that detergent ! It will foam forever !
 
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