oil pressure ?

[Buba Ganushe]

This does not happen often but on long trips via highway(like over an hour) the oil pressure gauge will start to fluxuate very quickly. this will continute until i stop the truck.

There are no major problems and the oil is at the right level as well as changed every 3000 miles.

Just currious if this is normal, never happened in any other vehicle ive owned.

Or any ideas of what is causing it?
Thanks

 

[Big Jim M]

I'd first look at the connection at the sending unit.
Big JIm

 

[Buba Ganushe]

thanks

 

[ranger1996]

my 96 was doing that when i would take off a stop light and when it idled. it still runs ok, but i think i am going to put in a new sender at some point

 

[TomB1269]

my 02 will do the exact same thing in the summer, and once you shut it down and restart it is usually stable. It is my understanding (big Jim & others can confirm) that Ford installed a resistor in the circuit for the needle that makes it read stable. If you notice in the cold the oil gauge is still in the same location eventhough the oil pressure is 10 to 20 psi higher when the engine is cold. My thought is the sending unit is getting weak, our trucks oil pressure is not quite as strong as it was brand new and these combine cause us to be sitting on the edge where the gauge would drop to low to show a problem. There is one other item that would light up if we were realy having oil issues, the CEL would kick on.

 

[oldfordman]

Buba- the other folks are correct- probably your sending unit. However- on these trucks the sending unit is just on/off and a resistor is put into the circuit so the gauge reads in the middle when you have a minimum pressure (I think it's only 8 psi). The sending unit is behind the right side head, and a bit of a pain to get to. If you are going to replace it, might be a good time to install a real gauge. If you are running 5-20 oil, you might want to try 5-30, the higher weight will give a bit more pressure when hot, and 5-30 was the recommended weight until about 2002 (I think), when Ford switched to 5-20 to get a tad more fuel mileage for the CAFE standards. I have been running 10-40 inmine for years with no problems, but I always let the thing warm up a bit before I go blasting down the road. Also, these engines are noted for the cam position sensor gear going. The cam position sensor asembly also runs the oil pump. many people replace it at about 90-100K just as preventative maintainence.
Tom-I do not believe the oil pressure sensor is hooked into the CEL.