Which condition do you have? In the thread title, you say water in oil, but in the thread you say oil in water.
I have a dt466 that had both problems at different times. The oil in water ended up being the oil cooler. I also had mine tested, but it didn't show as leaking unless it was at operating temperature. The rad shop i had test it couldn't heat it to 190 degrees and pressurize it at the same time. I replaced it with a reman one and all was well.
Several years later i found water in the oil. Fortunately, i caught it very quickly, and had no trouble with bearings or other lube damage. In that case it happened to be the liner seals. The very bottom one(s) had basically rotted out, and was allowing coolant to leak into the crankcase while it was shut down. I replaced all the liner seals and back in business again.
If you've got water in the oil, it's possible one of the liner oring seals twisted, rolled, ripped, or something while you installed them. If you can pull the oil pan and pressurize the coolant system, don't use 85 psi, 10-15 should be lots, a leak from the bottom of the bad liner will be easy to spot. Obviously you'll need the cylinder head back on to do this, or your block off plate if you can seal the coolant ports.