Was out on a test drive with a mechanic. Pulled the car in and opened the hood the overflow was boiling! He seemed to think it was a head gasket worst case?

Any sugestions anyone?

When I fire the car up after sitting all day a little white/blue smoke comes out then its done. I have a flowmaster on it.

Also, on the way home he told me to check the temp! Took the long way home on the freeway 1/2 hour home. Got it up to 110MPH engine temp stayed above 150-175 ish. Opened the hood up when I got home and it wasnt over heating? It was cooler out and the sun went in.

Im clueless and suggestions?

 

Make sure the cooling fan is running. It will show up at idle. The highway driving tells me the engine itself is OK. The blueish smoke at startup is very common, simply needs valve seals. GM has a kit for it. The cooling fan should come on at around 225-238 degrees. Also make sure the system is holding pressure, loss of pressure will lower the boiling point of the coolant. Head gaskets are not common, a leaking intake gasket at the coolant passage in the front is common with the TPI setups. Check the oil, if it is milky there is coolant in the oil. That needs to be addressed quickly or severe engine damage can occurr.