Weird radiator leak

[Matthew-1985]

Hi All,

I've replaced the tubing in my build but noticed that the fittings on the radiator leak if I open the port directly above it (I was doing this to try and get the air out).

The fitting which leaks is the one directly below the port I open.

I've added some photos below so you can see what I mean. Anyone came across this before? It's perfectly fine otherwise and has been leak testing for 24 hours without issue. Is there some weird physics explanation for this?

https://photos.app.goo.gl/qfVBMq1ir8iVAHQi8

 

[Jokester]

Not particularly weird, effectively you have a partial vacuum inside your loop holding the water in despite it not being totally water tight. Opening the port above to let air in equalises the pressure which then allows the water to dribble out the other hole.

 

[LuckyBenski]

Also, the actual end tank is brass and will probably be wrapped with a shell. If any water leaks out of the top port while open, it can probably travel down the outside of the end tank and leak through the shell.

Easy enough to test I'd think. Put some coloured fluid on the outside of the fittings and see if it leaks through.

 

[WantoN]

Try another quarter turn, then try different fittings.

As above, air can't enter the system, so it doesn't leak until you allow air to enter. Either that or a faulty rad.