zero oil pressure, Yikes!

Here's a good one for you guys. About 45 minutes running at 32-3300 rpm, alarm goes off on port engine. Quick scan of gauges I see oil pressure at zero. I shut down engine, pull hatches and look for oil in the bilge, none. Wire off sender? nope, check oil, plenty in there. So I start it back up, clatter clatter clatter, yup no oil pressure. This is bad. Shut back down for another check around for anything obvious - nothing. WTF? so I start it back up again and let it idle a few seconds still clattering but not real bad now, alarm stops beeping hey wait I got a little pressure 5-10 psi wait now 20 psi rev it a little 40 psi. all good. Ran about 6 more hours at cruise, Idle , trolling, with eyes pretty much glued to the oil pressure gauge - no problem. WFO for a minute or so when I got near the marina at the end of the day - all ok. The engines are '97 vintage vortec 350's I rebuilt and put in about a year and a half ago. they have been running fine, have about 200 hrs since the rebuild. Anyone have any idea what may have happened?

A momentarily loss of oil volume at the pickup screen in the pan?

Gary_D said:

Here's a good one for you guys. About 45 minutes running at 32-3300 rpm, alarm goes off on port engine. Quick scan of gauges I see oil pressure at zero. I shut down engine, pull hatches and look for oil in the bilge, none. Wire off sender? nope, check oil, plenty in there. So I start it back up, clatter clatter clatter, yup no oil pressure. This is bad. Shut back down for another check around for anything obvious - nothing. WTF? so I start it back up again and let it idle a few seconds still clattering but not real bad now, alarm stops beeping hey wait I got a little pressure 5-10 psi wait now 20 psi rev it a little 40 psi. all good. Ran about 6 more hours at cruise, Idle , trolling, with eyes pretty much glued to the oil pressure gauge - no problem. WFO for a minute or so when I got near the marina at the end of the day - all ok. The engines are '97 vintage vortec 350's I rebuilt and put in about a year and a half ago. they have been running fine, have about 200 hrs since the rebuild. Anyone have any idea what may have happened?

Click to expand...

Ayuh,..... How much is "Plenty",..??

Over the Full mark is worse than under the Add mark,....

If it was Over-Full, I'm guessin' the crank airiated the oil, causin' the pressure loss,....

Good point. Could be over full. The marine power cores I used had no dipsticks with them. I used my old crusader sticks, put in 6 qts and marked it full. maybe the marine power oil pans hold less oil? Hmmm.

Ayuh,.... Most oil pans hold 4 or 5 quarts, plus the filter,....

Well, changed the oil yesterday, sucked out just slightly over 4 qts from the pan (fit in a 1 gal oil jug) changed the filter and refilled with 5 qts 15w40 rotella - we'll see.