[horsa]

Hey Andrew,

Copied your image back in with an arrow pointing at the thing I was thinking might be a second breather since it looks really similar to the one on my rear deck going to the differential.

My coolers should be the 1st pattern but I have 2nd pattern as they were all I could source when I did the restoration. They don't have cut-off levers but I didn't realize that all of the later carriers omitted that feature.

Originally the T-16 had issues with oil coolers rupturing so the regulated pressure in the block being discussed might have been the fix. And also why they didn't need the cut-off lever anymore. My oil pressure has always seemed low to me being 15-25psi max even at full power for liftoff. Had thought it had something to do with my sending unit so if they run at lower psi by design, that makes me feel better. My jeep always has higher pressure right from the start and that's what I've been used to.

Your surge of high pressure could have been from a blockage in the line due to the by-pass being stuck. It broke free and is now stuck open so oil is going to your alternate route in the breather. I opened mine up before posting this and it contains a large metal ball at the bottom with a 1.5" long spring on top. A slotted plug down the well is screwed in over the spring and ball and then there is the large visible hex head on top of everything which is visible in my engine photo earlier in the thread. Don't have a diagram but it's fairly straight forward how the by-pass works. Pressure against the ball compresses the spring and allows the oil to take the other path.

In terms of direction, I think it flows from the line closest to where you and I have our oil senders attached. This is the revised location. Originally it was located on top of the housing beside the by-pass which would be reading pressure as it came back from the oil cooler as opposed to engine side oil pressure which is more important.