Weird D24T Cooling system?

[Volvoist]

Very interesting! I had one MLS gasket give me trouble on a fresh rebuild. It seeped a little bit of oil from the right (passenger side) of #1. I ended up having to pull the head off to find a mysterious oil burning problem, and subsequently the engine apart, only to find the problem was in the head anyhow... and I replaced the head gasket, again, with a MLS gasket and the problem was gone. I have no idea what the issue was. I suspect the head was not quite flat in all areas, and it leaked. I put a different head on anyhow to solve the oil burning issue, and never gave it another thought. Glad it is fixed for you now!