Ok, so I decided to install an oil pressure sending unit for a oil pressure guage. I got it installed but I'm getting very little pressure on the guage. I pulled off the oil filter housing an noticed that the oil cooler bypass valve is not seated in its hole. I pulled the unit out and it measures exactly what the manual says that it's supposed to 34.5mm when cool and moves freely so I know it's not stuck open.

My question is, is there supposed to be another piece that just sits in there to seal off the passage that could have fallen out when I removed the valve?

I'm thinking this is why I'm not getting pressure on my guage as the oil is bypassing the cooler where my guage is installed.

Here are a couple of pics, you can see that in the second one, the valve is not seated...