Oil pressure loss
 

I recently posted in the 97-04 forum about my 4.2L oil pressure problem. My 98 F150 has developed a beast of a problem. Driving at higway speeds my truck occasionally loses all oil pressure. It is a real oil pressure problem, and not a sending unit problem because at this point, i begin to hear tappet noise. I shut the truck down for a few minutes, crank it back up, and it returns to normal oil pressure. Since this problem first occurred (1 week ago) i have replaced the oil pump, and found a clean engine- no sludge build-up whatsoever. I thought I was on the road to recovery until today my first highway trip in the truck since oil pump replacement and the problem occurred again. I am at wits end, i only have 85000 miles on my truck and do not want to buy something new.
Thanks for the help,
E

erod,
Man I wish I could help, but I just don't know ???
Seems like I remember reading something somewhere (not even sure if it was a 4.2, or even a Ford).
Anyways. it was something wrong with whatever drives the oil pump - not the pump itself, but something involved in operting the pump.
I wish I could be more help.
Have you checked to see if something is floating around in the oil pan and occasionally blocking the oil pick-up? Sounds like that might be a possible cause of what you describe.

hi erod, the oil pump is driven by a thin gear shaft and this may be broken above the pump face, where is not visable. the drive shaft is part of the cam position sensor and can be removed by removing and lifting lifting upwards. then it will have to be re-positioned correctly.
i would also consider checking for loss of coolant because when the oil pump, pumps anifreeze it also cannot maintain pressure to the tappets. but this is more lightly to happen at very low revs.
hope this may help, bokker.