So I have read all the troubleshooting headings and haven't found this problem discussed. After the infamous split plastic impeller pump was replaced in my '96 V6, the replacement pump lasted long enough to get out of warantee then started leaking at the shaft seal. I am now on my third replacement, two rebuilts (plastic impellers) and a new off brand with an iron impeller. All three have leaked, the first one from the seal again. But the second two seem to leak from the gasket or the little ball at the bottom of the pump. I have just replaced the gasket and it is still leaking at the bottom of the pump. The housing was carefully cleaned of all old gasket and a new $9.62(!) Ford gasket installed. All bolts pull up snug so it doesn't seem that the housing is cracked. It started leaking as soon as the pressure built up in the system. The leak is definitely not at the seal and it is not running around the pump. I strongly suspect the little ball thing which has no obvious function. BTW the cone discussed as an impeller breaker is tightly in place. Any Ideas??