Onan MDKBT 27kw oil press senders

getting this odd glitch on BOTH 27kw Onan MKDBTs (2009 with 1500 and 2200 hours)

After running for longer time periods, at least 24 hours, oil pressure readings gradually goes down to the point where it will pre alarm on the Onan panel as well as the alarm on the boat Isis monitoring. Eventually, a few hours later generator will shut down with oil pressure fault.

I don't see any oil pressure switch in the parts book or wiring diagram, it seems that Onan uses the sender output to trigger a shut down.

Oil level good, changed the oil and filters on both units over the past few weeks but still happens. If anything the drop seems to happen more rapidly now, after 12 to 18 hours.

Both gensets show the same symptoms.

I have already ordered two sensors so I can replace them when we get back home on Thursday but I find it odd that would take so long for pressure reading to come down.

anybody seen that failure mode?

Forgot to mentions that along with great pressure drop, pressure also fluctuates fairly rapidly by 6 to 9 psi

Also, I checked the obvious including making sure the wire on the senders were tight but I found a disconnected wire next to the senders... White like the sender wire, same ring terminal but disconnected. Sender only has one terminal. Same loose wire on both gensets

Oil level is good, no fuel getting in. No smell. Using rotella 15/40

Level is mid dipstick so foaming not an issue. No sign of foaming when I pull the stick after shut down. I ll check the stoppers but paint markings would have been obvious.

I double checked th diagrams, no additional pressure switch. Only the sender which the electronics use to display pressure on the digital panel and to shut down At a preset value.

Problem is getting worst... Now last 10 to 12 hours before alarm is triggered. Second night in a row the Isis monitoring alarm in our room goes off around 5am good,thing we re on way back

No history or log. Used both Onan and purolator filter (all I coudl get) but that made no difference. First oil change was with Cat brand 15W40, second with rotella. I ve used rotella for 8 years/ 7000 hours on northern lights / 3000 hours on 3412Es with no issue...

Will check oil temp.

Going to replace the senders when I get to maimi and see what happens.

Looks like it turned out to be the senders. Replaced both of them and added a Tee with mechanical gauge. Ran 36 hours earlier this week and pressure held steady, no alarm.

Around 50/55... Not as precise as the digital but close enough.