Slow Bubbles Into The Resevoir Tank

[Drag0na5h]

Recently I replaced the heater core vacuum inlet valve unit that opens up to allow hot coolant to flow into the heater core. I believe this was the cause of my consistent coolant loss in the past because there had always been a wet spot right below it and now there isn't any. Also, I burped my coolant system three days ago and got most of the air out of the heater core / coolant system, I assume.

So now I have been starting my car up and driving it around allowing it to reach operating temp and the T-stat to open up. After which I park on level ground, engine still on, to take a look at the coolant resevoir tank. I notice with the resevoir tank lid off, but the rubber hose still submerged in the coolant, that there is a consistent slow bubble that burps up from the bottom of the hose. Maybe one every second and a half. After I turn off the car and look at the resevoir tank the same way, the bubbles increase to about two every second. Within this month I have replaced the T-stat and radiator cap, both Toyota OEM parts.

A key thing to note is that my coolant level for the past three days has stayed the same level in both the radiator and the resevoir tank. The level in the resevoir tank stays the same before and after turning the car on and off. I'm just getting this bubble issue that I don't have any experience with to know if it is normal or not.

EDIT: I just checked the resevoir tank 20mins after I turned off the car and the bubbling has ceased. The coolant level in the resevoir tank is still at the same level as before and after the car was turned on and off. As far as the radiator I will check once it is completly cooled down.