I have one of those Bitspower water exhaust fittings, but I do not use a leakshield.
If the provided end cap was not installed, the fitting would ooze coolant over time.
Adding the end cap seemed to stop the discharge, even though there is no O-ring.
If you are using the end cap, you may try adding an O-Ring to get a better seal.
I used a
Bitspower ML O-ring for 16mm OD tubing
(
no_o-ring.jpg)
(
with_o-ring.jpg)