Not unusual for wp impeller crack to cause loss of adhesion at shaft, therefore no pumping, however usually bits of impeller would also have broken off.
Don't think air bubbles are the problem. Did you replace 'stat with proper temperature one and did you re-assemble correctly?
98 Mystique LS v6 atx 110,000km
97 Contour LX v6 atx 125,000km
stock CD on LS, cass on LX
spoiler, tinted windows on LS only
4 wheel discs on LX only
All other available options on both
| 
