So, was removing the oil pan today to get the engine ready to ship out for rebuild and there was a bolt that sat proud of the bottom deck. It clearly was related to the front oil take-off for the oil cooler, but it looked almost like a plug. And I couldn't see any other clear way for oil to get to the take-off. And I knew that couldn't be the case that it was plugged, as there was oil in that line when I removed it.

I hesitantly removed it despite it being hella-torqued (figuring it was going for rebuild anyways, couldn't do any harm even if I unleashed something terrible). And inside was a large spring.

I can't see much inside or even around the housing. Obviously the oil pump is immediately adjacent to this. Is this a thermostat of sorts? Is there an orifice that goes from the pump housing over to the take-off and this functions as a themostat to open when the heat reduces spring tension?

And -- a little late now probably -- am I fine to just remove the bolt and the spring? Is there something else in there I should be trying to remove that may fall out or dislodge in transit?

 

Magnet on a stick will be your friend.....don't lose the piston on top of the spring!

 

See, good thing I asked, as I couldn't see there was a plunger in there. I see that now. Thank you.

But, are we certain that it comes out the 'bottom'? Because I can pull it with a magnet and it seems to hit the threaded area and just stop. Seems too large to come out this direction...

 

Oil pressure relief valve. No real reason to remove it other than cleaning. I've never actually removed one completely before. I think it can only come out the bottom though

 

Played around with it a bit more. After a few minutes the plunger bit somehow just decided to come out.

Found something interesting though. In the end of the bolt, right where the spring seats, was a piece of broke spring. It was in there 'broken' edge up. I thought that maybe it somehow broken when I removed it. But it is almost certainly not part of the spring that was in there. The spring has smooth ends that were clearly cut, not jagged like the broken bit, and it has a slightly different finish.

I can't even imagine how this spring would break at all.

 

I found a relief spring similiarly broken in the past, but that was a failure.

Hard to imagine someone has overlooked it previously. Can't tell you what it is, there should be a spec for the spring in the manual and maybe someone has tried to compensate that way for lost length. Could also be a misguided effort to shim the pressure relief.....hopefully no crushed regulator to get "better" oil pressure in the back of your engine either!

Edit: First pics show the reg in the background, so ok on that score!