when I was getting my seals replaced on entire car this winter ($5k job) the guy recommended I get a ANTIFREEZE seal fixed that leaks a lot of time.. i suspect this might be this part you did not get replaced ... because it leaked in the same freken location just not as bad.. a few drops a night.. i had to fill up on coolaant every 2 months.. after seal was fixed i did not have to top off coolant in months