[Hib Halverson]

If you mean, when you say, "pushing bubbles into the radiator", that when you take off the cap, start the engine, then look into the high fill bottle, after the engine runs a while you see some bubbles in the coolant flow that enters the tank near the cap, if the bubbles are small, continue for a short period and don't smell like exhaust, I'd say that's normal.

However, if you suspect a head gasket problem, I'd run a cooling system pressure check, that will find a head gasket leak from the cooling passages to the bores.

You can also run a cylinder leakage test and find a head gasket issue.

If it's really bad you even can find it with a compression test.

Also, if you find someone with a borescope you may be able to even "see" head gasket problem.

If you have a head gasket leak from coolant into the oil, you have the baby s&%t looking creamy stuff on the dip stick.