[99zhfkaf]

i am having the same issue w/my 99 passport. i thought it was a radiator, had it replaced and a month later i was low again. no idea where the coolant goes, no drips or smells. my mechanic claims all tests say head and block are fine. no white smoke out of the tailpipe either. he thinks it's a small leak near the thermostat, in an area covered by the intake plenum(sp?), engine cover and pretty much everything on the top of the motor. let me know if you find anything out. right now i am just checking my coolant level every 2-3 weeks and topping off as necessary.