96 v-10 with 190,000 on it

The oil pressure use to run just over 40 psi (warm engine) on the dummy gauge, and build pressure after about 2 seconds upon start up.

Now the pressure is below 40 PSI (warm engine) and it takes about 10 seconds to build pressure upon start up. I also noticed the engine has a rough idle, and when i shut it off, as its spinning down it makes a knock noise, unless the clutch pedal is depressed. The knock is probably something else, but I just noticed the issue.

Question 1:
Does anyone have any experience with oil PSI on these trucks, or understanding of the oil system that could explain why it's doing this?

Question 2:
Where is the oil sending unit so I could plug in a mechanical gauge, and is there any adapters necessary for a gauge?

Question 3:
Has anyone had an issue with knocking as the engine spinning down?

Thank you for reading and replies!!!

 

The oil sending unit is probably due for a change, they become less accurate with age.

Not sure if the v10 is in same location as v8, v8 is just left of distributor. Remove sending unit with a short open end wrench, may need to cut one down to fit. Install mechanical test guage in it's place.

 

#1. My V10 with 110k on it has the same pressure as yours all the time. Hot or cold doesn't matter. ~40 psi. I've put a mechanical gauge where the oil pressure sending unit is and had the same numbers. Not sure why yours dropped off all of a sudden. maybe dirty pick up screen in the pan?

#2 The sending unit is on the filter housing where it bends back to the timiing cover. Very easy to reach and replace.

#3 Not yet.

 

Most of these sending units are after your oil filter in the cycle. Depending how soon you need to change it and also. When the sending starts to get bad they leak which gives a bad reading. I've changed a few of them they wear out over time. It's enviable. I always buy 2 and keep an extra on hand cause I've bought new ones that died in a few months