Oil pressure gage not working on 2000 Ford Explorer with 4.0L engine: No codes

Question:

What could cause my oil pressure gage not to work momentarily when stated cold? This happens for 30-40 seconds but sometimes could last up to 1-2 minutes. However, after the engine has warmed up, the gage works great until the engine is shut down and gets cold again. Some friends said that the sending unit is defective but I need your input first.


ATS Advisor:

The normal mechanical oil pressure gage usually shoots up in reading when started cold using the regular type sending unit. However, Ford has used a different sending unit which has caused a lot of problems such as yours. Regular sending units usually work by pressure difference being monitored but this type of sending unit works like a "switch" instead. An updated sending unit is available from Ford to prevent this problem.

ATS Tip:

Make sure the engine is mechanically sound by checking the actual oil pressure with your own oil pressure gage tester. Do this before installing the new updated sending unit.