Nissan Repair: nissan sentra trans/speedo problem, nissan sentra, shaft seal

Question
I have a 93 Sentra 1.6l w/auto trans.  My problem is an intermitten one. On occation I'll be driving along and my speedometer will dump to zero and I notice a downshift or drag on the transmission, after a few miles the speedo pops back up and everything is fine.

Answer
Steve,

It sounds to me like the engine is cutting off and then coming back on.  I would check the fuel system for a drop in pressure or the ignition cutting out.  From my experience it sounds like the distributor is going out.  After this many years the shaft seal fails and allows oil to wick up the shaft.  Then, it gets on the optical trigger and shutter wheel and then you have the cut out you are experiencing.