Problem with bubbles in my W/C sys.

I have the RBX , Hidor L30, a simple rad.
every thing is connected and im using a T line.
Im playing with the pump to get all the bubbles out and it takes me
about 2,3 minutes.
after making sure all the bubbles are out i run the system with out shutting
it down and when it starts everything is ok. but after about 20 sec
the pump is starting to make some noise and the water goes up
the T line, pressure is building up, and the air gets stuck in the RBX in the outlet before the Y connection.
I assume that some how the pump isnt sealed the way it should and somehow it sucks the air in.
Is it possible for the water to go inside the pipes with out any water going out?
Is it really the pump?
the sys. is runing for about half an hour now and the problem is the same

1. look where air gets into cycle, eliminate these spots
2. T-line should remove air and bubbles, if it doesn't tryto make it work - it's not only for adding water
3. fluid for car radiators has anti-bubbles stuff

1) cant tell where air is coming in but i think its from the pump
2)i know T line should remove bubbles but the water is comming up the line and air some how gets in
3)i have in the mean time regular rad water.
all the anti freezers i found were green so im still waiting to find one who is not green

Antifreeze is a poor choice for an additive IMO. The additive needs to inhibit corrosion and not interfere with the heat transfer process. Antifreeze scores poorly on these accounts. Try a product like Water Wetter instead (which is purple btw).

Anyway, yes it is possible for air to get sucked into the loop without water leaking out. Before reaching that conclusion you should make sure the system is indeed air-free or else that it will not get air-free no matter how long it takes. This means trying the bleed process for a few hours, if you can.

So if there is indeed air seeping in somewhere you'll have to find the problem spot yourself. There is really no way around it. Sometimes you can hear a slight whistling tone originating from the leak, sometimes not. It's a good idea to check all connections anyway and make sure they are firmly sealed with clamps. If nothing helps so far, you may be facing a block/pump/rad leak...