Oil pressure being a common discussion point, I have a random issue. A few times at the start, I have had zero pressure on both the dash light and gauge I installed. Turn it off, restart, and it's fine. Actually, really good or normal pressure for a 193k 2004 4.6. 52psi cold, settles in at 18psi hot idle, jumping up to 35-40psi under throttle. This has only happened twice this winter, so not a common thing. Is there a valve in the pump housing that can stick? I know oil filters can have pressure valves. And on that note, I have noticed the oil pressure can be sensitive to what oil filter is used. Any thoughts appreciated.

 

There is a pressure relief valve but it only opens at 55 psi. Unlikely that is your issue. We have had members with a rag in the sump getting picked up in intake.

 

Do you have separate pressure senders or are both working off one sender? Has it been super cold where you are?

 

Separate senders. Yes, it has been cold here, but in one instance, it was not that cold. I replaced the front cover/oil pump about 10k miles ago, and replaced the O-ring in the oil filter housing adapter pictured below. When that failed, it had a similar symptom, plus the opposite issue: running at higher psi nearly all the time, which was nice but an all-or-nothing type of scenario. lol, could be related, I guess.

 

I'm the only one who's been in the engine the last 25k and had the pan off, etc. But I did leave a rag in the airbox for about 6 months, fortunately on the inlet side of the filter.