Originally Posted by zeicher
my boyfriend is having to replace his moms alternator on her focus, i know when we worked on mine it was recommended that we not buy non ford manufactured part when dealing with the O2 sensor, is it the same for the alternator? or in that fact any engine parts?
The recommendation to stick with factory original parts generally applies to electronic engine management parts and emissions system parts because they affect engine calibration and fuel economy. The O2 sensors are part of that mix.
The alternator and associated battery charge system is definitely not part of the engine management system. If you buy one rebuilt from Ford it will be same as aftermarket except double the cost. Don't get the cheapest possible aftermarket unit though. Notice the warranty...the one's that are short are often not thoroughly rebuilt. I'd stick with AutoZone or Advance Auto or some popular aftermarket supplier. Some of the cheapest rebuilt alternators sold at chain stores are indeed bad news, since they may only be cleaned up higher mile units with little testing and no parts replaced.
I have had excellent experience with lifetime warranty rebuilt alternators and starters from the aftermarket chain stores, specifically Auto Zone and Advance Auto. I find they last long as new Ford parts, generally 150K mi or so. Most have 100% new bearings and rectifiers and the winiding and other parts are fully tested for impedance to ground etc. The factory ford rectifier block uses crimp connections which tend to slowly carbon up and burn open. This is what generally causes the OEM alternators to fail. The aftermarket units are actually superior in that respect.
I'd stay away from the incredibly cheap "new" lifetime units because they are generally inferior asian aftermarket designs using 2nd rate quality parts. They are so cheap, it's really not surprising. I had those fail within months more than once.