I have noticed the past two winters that my oil pressure gauge drops to zero inthe cold when I first start up. After about five to ten minutes the gauge stays steady within normal range. Could this be related to my sending unit or something else?

Some background:
2001 F150 XLT with 192,700 miles, no fluid leaks at all, no rust, Tranny is topnotch, and engine still operating solidly.

So, if someone can assist me i appreciate it.

Mike

 

If the oil pressure were truly zero the engine would seize, so it's most likely the sending unit.

 

+1 on the sending unit. Keep in mind, the gauge either reads ZERO, or about half-scale, it does not show fluctuations in oil pressure that a true oil pressure gauge does. The sending unit is a "normally open" switch, that closes with about 7PSI of oil pressure. When it closes, the gauge goes to about half-scale.

 

Like an IDIOT Light with a needle?

 

Exactly!

 

Then it would seem that during cold mornings the sending unit is not receiving 7PSI to close the switch, or the unit is sticking open when it is cold. Is it an electronic or mechanical switch? The later would fit this supposition, the former would not.

 

The sending unit "switch" is mechanical, with electrical contacts. They can stick open, or intermittently open when cold.