It leaks right to left or lower cylinder to upper cylinder.

I take them up to 8 psi, one at a time. With the left/upper cyl - it holds 8psi with no readable drop for atleast 10 minutes.

With the right/lower side, there is an immediate drop before reaching 8psi. It seems to hold ok at no higher than ~3 but any more than that and down she goes. It takes maybe 2 minutes ish to drop from 8 to 3psi.

I have a blank that allows me to test one side and blank the other inlet off, sealing the engine as a whole. With this in, the right side loses pressure at first, but leaks more and more slowly before stopping and holding pressure 100% - once the left side has become pressurised by leakage from the right. This test was of course the proof that it could only be an issue with the center seal.

After repeated tests the left side always sealed 100% without fail.

Then as i said i'd run it for half an hour or so - come in and put a new test on. This time both sides would seal 100% - a happy outcome but it'd be nice to firgure out what causes the cross leak before hand and what causes it to cure itself after!
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