Thread: Pressure test new cooling system?

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I will soon be at the point of filling the new cooling system in my LS powered Healey. I'm thinking of rigging up a way to pressurize the DRY cooling system to 15 or so pounds and allowing it to sit with a gauge attached to check for any leaks. This would be the same as checking an AC system with vacuum. I have also saw AC systems pressurized with nitrogen to check for leaks before pulling a vacuum.

Anyone see any issues with this idea as long as I keep pressure lower than radiator cap pressure?

I'm running a separate expansion tank since the radiator is lower than the engine. I have a couple of places where it would be simple to introduce air pressure. I know that you can get radiator test kits, but they have small hand pumps and would take a long time to pressurize a dry system.

As long as you have a reliable pressure regulator and a good gauge, should work just fine.

Kinda what I was thinking, but I don't know everything. Don't tell my wife I said that!:

It's a great idea, and in fact I'm thinking that Glenn Sexton(?) may have posted something about always doing a dry pressure check before adding any coolant to eliminate surprises..... and unexpected mess.

I think it could be helpful, but... I'm wondering the "density" difference of water with a Specific Gravity of "1", and air = assume a "0".. you may discover a "leak" that you wouldn't find when wet. I have no factual information at my fingertips, except that when we are testing a water pipe, it must be done wet. If the calculated average volume is expected to be 1/4 to 1/2 full then we must fill the pipe to at least 2/3 full and then cap and tap - add air to what ever spec is required. If you use Nitrogen, the molecules are larger than Oxygen molecules and again will show no leaks but then when you charge with air.. you'll have a leak. This is why the tire shops offer a filling with Nitrogen for a couple bucks as you (theoretically) won't lose tire pressure when filled with Nitrogen.

My thoughts fwiw... LOL.

The liquid fill requirement may be to limit total compressible volume, to minimize potential for damage in case of catastrophic failure.

Oh, and my perspective on filling tires with all nitrogen vs. 78% nitrogen: 100% bs.

Originally Posted by firebird77clone

The liquid fill requirement may be to limit total compressible volume, to minimize potential for damage in case of catastrophic failure.

Nah.leak test is only using 10 to 12 psi.. once in a while some engineer goes wild and specs 15 psi for 24 hours.. it's just a leak test.. Pressure test - depending on the expected operating pressure, we would probably bury the pipe to contain any shrapnel..