I don't think 210 is that bad. If the system is properly pressurized, you shouldn't boil over until you go over the 220-230 range. It also depends on the ambient temperature. If the condition you are describing is on a hot day, then it is completely normal. If it is reaching 210 on a cool day (<70F), then you may have an issue. Rule of thumb is, no boilover, no problem.
Wynona loved her big brown beaver
And she stroked him all the time.
She pricked her finger one day and it
Occurred to her she might have a porcupine