Got my block back from shop, what is this?

[ripewithdecay]

I just got my block from the machine shop and noticed this while i was painting it( dont mind my poor masking job):


What I'm concerned about is the oil filter area and the frayed metal circle with what looks like a spring or heli-coil or something inside it. I can't remember what its supposed to look like and am not sure if I should be concerned or not. Any help would be appreciated.

[ripewithdecay]

Well I was able to find out what it is. Oil bypass check valve. Should i replace it or just remove the spring? Seems like some people actually weld it shut too. Just not sure how vital of a part it is. Also to anyone who has replaced it, do you have to drill it out or is there an easier way to remove it? http://www.courtesyparts.com/15132m-val ... 23658.html

[Rev_D21]

Looks like the entire filter assembly is missing.

[ripewithdecay]

I have the assembly.

[ripewithdecay]

In case anyone else runs into this problem here is the info to order one on courtesy nissan:
[15132M] VALVE ASSY-REGULATOR - Truck (D21) 1986.5-1995
Item# 15241-D21001

Also if you are wondering how to get the existing one out, here's a "tool" you can make to remove it. I just took a bolt and ground it down somewhat. There are raised tabs on the back of the valve that the "tool" will catch on. I just used vice grips on the "tool" and pulled towards me multiple times and the force of it tapping on the raised tabs made light work of it.