oil pressure relief valve

[gingar]

can anybody tell me where this oil pressure release valve is on the 4.0 serp gradually lost oil pressure on hot idle and running, tappets where getting noisy too,dropped sump and cleaned wasn't too bad pick up was clean and tight, wanted to check release valve before I go for pump but can I find it..... no!!! got an oil pressure light switch the a 20mm bolt underneath but its just like a bung nothing in it and the gallery goes through oil filter.... help plz

[QBee]

FWIW, mine starts at 40-45 psi per the gauge stone cold sober, and can be below 30 psi when hot. Its now a 5 litre, but did the same when it was a 4 litre.
Personally I think the gauge reads well low, as the car is fine, uses little oil, oil is new, engine is only 7000 miles old, oil is full and there's no smoke from anywhere. And the engine sounds awesome.
Is the pressure relief valve on top of the rocker cover, or is that something else?

[phazed]

As you look at the front timing cover, L/H side near the bottom.

iirc, circlip, cap, spring and plunger.

[jojackson4]

Put a hand over it when the clip comes out
Mine was like a built