My K10 has an expansion tank off the radiator, where I get bubbles.
If I left radiator cap off, filled radiator 1-2 inches below top, radiator would just overflow. I'm sure I'd see bubbles there on normal idle.
I just did test, radiator full, expansion tank at correct half level.
Warmed car up, water rose to top in expansion tank, then pushed out of overflow for maybe 10 mins.
When I switched off car, get 5+ min of bubbles in expansion tank, then level in expansion tank gradually dropped to the bottom of expansion tank.
So had lost 4+ inches of water in expansion tank & probably top 2 inches in radiator.
Couple of months ago I checked cylinders, took out spark plugs one by one, engine continued to idle on 3 cylinders when spark plug removed for each cylinder.
Could not see any water in any of the cylinders.
