UPDATE...
I found the oil pressure relief valve location! I had to remove all 3 belts from the front of the engine and then remove the cambelt cover. The cambelt was removed and the oil pump is located bottom right of the engine. I had to loosen off the air con pump to remove the oil pump. Once the oil pump removed i unbolted the pressure relief valve... It was stuck because there was a build up of thick sticky oil just like tar! Gave it a good clean and it springs open and closed nicely now.
Took me almost 8 hours to do so its a huge job! I hope this can help someone else :)