radiator bubbles?

[PKRWUD]

Two points to understand here:

First, coolant retains heat, and raises the boiling temp of the fluid. Loosely translated, that means the fluid will be hotter, but will resist boiling.

Second, In order for the cooling system to avoid boiling over, it must be sealed. Loose hose clamps are a possibility, but a weak cap is more like it. The lower the pressure rating of the cap, the sooner the fluid will overflow.

Now, since the coolant allows the fluid temp to be higher, more pressure is created. With more pressure, you need a higher rated pressure cap. I would go too a 16 or 17 pound STANT LeverVent cap, and make sure you don't have more than 20% coolant (w/ 80% water) in the system.

Take care,
-Chris