I posted this thread because I was helping a friend with a fluctuating oil pressure problem and we were discussing how the oil flows in our engines. The conversation shifted to the oil bypass system, which I discovered I knew almost nothing about. I've known about the oil bypass built into some of our oil pump covers, but never really learned what it was there for. What I had no knowledge whatsoever about was that there is a second, primary, oil bypass device in the center of where you screw your oil filter to. Both work the same way by using a spring that presses on a ball that blocks a hole leading to a bypass passageway. The purpose of both is to bypass oil that can't get through a clogged filter, passageways, or other obstruction. They can fail and cause oil pressure to drop if the springs get weak, the ball doesn't seat well, bypass passageways are blocked with crud, etc. We can get rebuild kits for the ones in the oil pump covers, but apparently not for the one at the oil filter. With our engines having 50 years of wear and tear on them, a lot of engines appear to have issues with worn, weak, or gunked up passageways.
There's a mod. Now, I'm not advocating this "mod", I only heard about it yesterday and don't know what adverse issues doing this might cause down the road. The mod is to remove the pressed in cap with the bypass hole and the spring and ball, then tap the remaining opening for a 3/8" plug, and plug off the bypass, thereby disabling it. There is now no oil pass function at the oil filter, but you still have one at the oil pump. Theoretically, you could install the flat type of pump covers with no bypass function built into them and have no oil bypass in the system at all. The negative consequences would be that if your filter clogs oil won't get bypassed back to the crankcase. However, if your bypass springs are weak, or the balls aren't seating or get stuck, your engine can bypass the oil prematurely or all the time. This could be a cause of low or fluctuating oil pressure on some engines.
So, that's what I think I know about all this, so I thought I would share this knowledge with you guys and start a discussion about it.
Start talking.......