ok been a mechanic for 20 years now big trucks and heavy equip but now due to horrible svc from local ford dealer i have had this dropped in my lap 04 stock 6.0 changed oil stem in oilfiter housing cause it cracked also found some other PIECES in oil filter housing but also found a spring too cleaned out and now no oil pressure at idle rev to 1500 rpm have 80 psi a tech a=t a shop said ther was a relief in bottom of filter housing about size of a dime with a hole about 1/4 diameter he said plu g it and see if you have oil press at idle yes it works but when i call local dealer they have no clue what iam looking for he said there was a kit and they start giving problems about 120.000 miles any help or ideas where or what to get for svc parts learned a lot on here so far

 

There is a oil bypass valve on the bottom of the oil filter housing that is held on by two fasteners. Have you checked oil pressure with a mechanical gauge or are you using the dash gauge? There is a test port on the filter housing.

 

there also is a plastic anti drainback valve kit from ford for 8.68 and its pn 6800fz installed on my other 6 trucks and all my oil pressures came up on those as well