Thanks Jim,
The thing is that today when taking the car out for a ride I noticed a stream of trans fluid flushing, the a close inspect showed that the hose attached to the steel line coming from the rad was disconnected, and that was the problem. I know it has to be all one steel line, but at some point of the car's life, it's has been cut and now it has a part of rubber hose, just at the end, when it connects to trans. I don't believe I have flushed the almos 8L you mention, maybe only the half or a bit more, so will have to add slowly and check several times.
Thanks Jim,
Josep