Lower Oil Pressure Relief Piston and Spring

[dduclaux]

To all -- I am in need of some education regarding the lower oil pressure relief spring and piston. I'm in the middle of the bottom end rebuild of my 3.0SC engine (the first part of a total rebuild), and when I removed the lower oil pressure plug (on the bottom front of the right half of my case), I found the heavy duty spring and the inner sleeve, but there was no piston atop the spring. Upon examination of the oil passage, there appeared to be a brass-looking plug lodged about four inches up from the bottom in that passage. I removed the oil pressure indicator light sender and the brass fitting on the top side of the case to inspect it from the top. It appears that the same brass plug described above is lodged about 12 to 14 inches down that passage. My questions are as follows:

1) If I were to look at a cut-away of the block, would I see a continuous passageway that ran from oil pressure light sender at the top of the right case half to the oil pressure relief spring plug at the bottom of the right case half? In other words, is the brass-looking plug I describe above possibly the piston that sits atop the relief spring and is it lodged in a passage that I should be able to look straight through?

2) There appears to be only one port in that passageway at the top near the oil pressure light sender and it seems to "connect" with the area of the case where the thermostat is housed. Am I correct here?

3) Can someone help me understand how the oil pressure relief piston and spring operate? Is oil forced into that chamber for the sole purpose of gauging the pressure to activate the "idiot light" or does it serve some other purpose?

4) Do I really have a problem here, or is the function of that oil pressure relief piston and spring marginal relative to the functioning of the engine?

Thank you very much for you time and insight.

Duane Duclaux