A little update – I did another compression leak down, at tdc , bdc , and mid travel. No bubbling through the coolant at all.
Very interesting…..If this is true for all eight cylinders that would indicate some how an external to internal leak …
At that point you would need a complete diagram of the coolant routing and passages for that specific engine.
My only other thought,
If after running the engine and having water vapor expelling out the exhaust, pull the plugs and inspect both the plug and cylinder for signs of coolant.
Perhaps there is a coolant leak somewhere in the throttle body, sucking coolant in the intake.