Safe pressure for radiator test?

Sparky

Sparky

Well-known member
I have a small leak somewhere in my radiator so I want to pressurize it to locate the source. I have heard that 5 psi is a safe upper limit for pressure testing. Is this correct?
 
Safe from what? Learning the real truth, discovering economic doom? I've tested every A I've had at 15 psi. If the radiator, hoses, head gasket, block can't hold more than a few "safe" psi I don't consider their condition OK just because they don't leak when not pressurized.
 
Safe from damage. Modern radiators are designed to hold 15 psi or more; I just wasn't sure if a Model A could do the same.

What's happening is that it is leak free when cold, but after getting up to operating temperature for a while there is some seepage. Im guessing there is a small crack in a solder seam that opens up when hot. I will be preesurizing the radiator only, not the entire cooling system.
 
You can use an old bicycle inner tube to pressurize the radiator. That way you can find the leak with low pressure and no chance of an accidental high pressure burst.

My original radiator on my 28 Phaeton had just enough of a seep to make a couple tubes damp of the front of the radiator. A can of leak sealer took care of it, and it's been fine ever since, even after my cleaning treatments this past summer.
 
Sparky said:
Safe from damage. Modern radiators are designed to hold 15 psi or more; I just wasn't sure if a Model A could do the same.

What's happening is that it is leak free when cold, but after getting up to operating temperature for a while there is some seepage. Im guessing there is a small crack in a solder seam that opens up when hot. I will be preesurizing the radiator only, not the entire cooling system.
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Henry's original soldered radiator was way heavier/thicker than any new stuff, even though it was not run pressurized. When new, it would have easily held 15psi. Of course, the metal and the solder seams have deteriorated since then. The question is how much? To me, a cooling system that pops at more than 5psi is just postponing the inevitable, even if it doesn't leak today. If it were out of the car I would want more reliability than that, but there is risk that you will find the bad seams sooner rather than later. I have two original 31 rads that both passed a 20psi leakdown test - after resoldering the tube sheets, tanks, neck and overflow tube. Neither leaked when I got them, and I suppose I could have just used them, but that's not my way.

I do not consider 5psi radiator testing protection from "damage". To me it is protection from too much information that some may not want to know.
 
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