Recently I heard some noise in my truck f150 V 8, 4.6,2010 engine. Prior to that I noticed the oil gauge keep fluctuating. It comes to low and then bounces back to normal .so I sent it to the mechanic. The engine was dropped and we found out oil pump was damage. It was replaced with new one , and engine properly serviced with new bearings.
Now truck has been started and it's smooth. No noise from engine. But again the alarm has started coming back. The gauge hit low then it goes up again. Please can some one explain to me what is happening and auggesugges to make it work.
The filters replaced and oil changed.

 

Was the oil pressure sending switch replaced or not?

 

Is this 4.6 the 2 valve or 3 valve engine?