But bubbles in your coolant have a lot of places to hide. The only way to truly tell is let it run very low on coolant (if it does) or pressure test it.
------------------------------------------------------------------ 1992 300ZX NA 5 Sp (Dead) 1990 300ZX NA Auto 2+2 (Dead) 1990 300ZX TT 5 Sp (Building) 2004 G35 Sport 6MT (DD)