Oil pressure dropping

[carco]

(07-19-2020 )Rawze Wrote:  

(07-19-2020 )carco Wrote:  Hello to all during this hot stretch,
2009, T8, ISX550, 326000 miles, 14400 hours, empty weight 52K, loaded usually 65K to 90K often up to 130K but has been up to 167K, and once 232K.
Oil pressure has been dropping last 4-4500 miles 68mph, 1700rpm oil 39psi is now 33psi hot.
Hot idle oil psi now 16psi was always over 20psi. No power difference, no sound difference.
Was ready for oil change, 10 to 12K service intervals, so changed oil, made no difference. Changed oil sending unit, no difference.
So am I in trouble just over the next hill?? just keep an eye on the oil press?? tear down the engine, pull rocker cover chk cam, pull pan chk rods and mains??
Any words of wisdom?
Thank you.

just an FYI: If you had claimed that oil pressure comes bnack whenever the filter is changed, that is a common issue.. but you did not state this. - In the case of oil pressure falling off, then a fresh oil change and filter makes it come back, that is a sign of severe soot packing in the oil.

-- If your oil pressure has fallen off that much, and it is consistently bad ... I would pull the enigne cover and check for a spun bearing on the cams first. --Then the bottom end to ensure something is not getting beat to death, and check for debrtis in the pan. -- still nothing.... then replace rod and main bearings and replace oil pump while your at

When replacing rod/main bearings: -- BE SURE TO MEASURE all your rod and main bearings, as some ISX engines have alternate sizes and this can really screw things up. Not all ISX's come with standard size bearings from factory. They can also sometimes be different from hole to hole too.

Rawze,,
None to very minor oil pressure change when oil is changed.

Oil pressure has dropped to about 38-44psi hot. At cruise 1700 rpm/68mph steady flat terrain will vary at times down to 38psi and back to 34psi. Also hot low idle about 14-15 psi now.

New oil sending unit was No different than the old unit.

Was really hopeing someone would say YES, this very thing occurred and this is what worked,,,,,,. Theharjot is the closest to answering this way!! Thinking about starting that direction w/new oil pump and pulling cover to look at top of head for problems. After a manual gauge chk.
Thanks to all for your time and thoughts!!

On another note I need to see why I have not received email notices on your posts!! That is why I have been so long to respond back, busy and did not know of the responses! Thanks again