i have a 97 ford f150 v8 ,4.6 engine

low oil presuure at start up completely rebuilt engine 4500 miles on it
after 3 minutes oil light goes out and pressure is normal till statr up the next day? all other operations with start up after that are fine untill the next morning need some advice???? please

 

Three minutes is a long time. Do you hear any valvetrain noise while the pressure appears to be low? I know oil filter brand is going to come up and most everyone here are pro Motorcraft users as it has a drainback valve which helps prevent dry starts. But again I wouldn't expect the pressure to take 3 minutes to overcome a partially empty oil filter. Has this been an issue since the rebuild for the entire 4500 miles? Another thought would be the O ring that is suppose to be at the end of the oil pan pickup tube right where the tube fastens to the oil pump. If it was not in place when the tube was installed you can get a bleed back from the oil pump and delayed suction as well and as always a defective oil sending unit can give a false reading indicating low pressure.

 

Replace the oil pressure sending switch.

 

That answer is to simple projectSHO. Come on you have to have some fun with this. I like throwing a bunch of ideas out there that way if anyone does a search on a particular problem they can have a list of possible root causes for their concern. Besides I'm retired and have too much time on my hands

 

Okay, fine.

Remove the oil pressure sending switch and install a mechanical oil pressure gauge. Test-run the engine to see if oil pressure comes up immediately or is delayed. If delayed, troubleshoot oil pump system. If not, remove pressure gauge and install a new switch.

That will give him something else to do.

 

Incorrect oil filter or defective anti-drainback valve?

To heavy an oil viscosity or oil that has been in there too long and thickened?

 

Just riding ya. Sometimes I get long winded on these posts. Take care.