Would "Bubbles" refer to a potential air lock in the heater?
All three of my Morgans ('76 4/4, '97 +4, '93 4/4) have had really good heaters...


Graham (G4FUJ)

Sold L44FOR 4/4 Giallo Fly
'11 MINI Countryman Cooper D All4
'90 LR 90 SW