Yesterday my z started overheating while driving down the highway, temp got to just under 3/4 on the gauge. I turned the heater on 90 degrees and full blast. The temp went done pretty quickly to 1/2 on the gauge.

When I got home I checked the coolant reservoir and fluid level was just below the min mark. I opened up the radiator cap and bleeder and slowly filled via the radiator.
Let the motor heat up and then shut her down to cool off.

Took it for a drive this morning the radiator fan kicks on as soon as i start it up and it started overheating around 10 min of city driving.

Got game and tried to purge via the bleeder and funnel method (using regular funnel held in tightly)

The funnel filled with coolant once the engine heated up but no bubbles came out of the radiator. There were lots of tiny bubbles like foam coming out of the bleeder. Let it run like this for about 10 min until so much coolant was coming out of the bleeder that it was spilling all over and evaporating into coolant smoke.

Does this sound like air in the system, thermostat, or head gasket?

Thanks

 

My car did the samething when my thermostat went bad. They are cheap and easy to replace, so I'd start with that.

 

Thanks. I was thinking the same thing. I had been missinformed by someone saying that the heat wouldn't work if the thermostat was stuck closed.

 

Feel the coolant hoses after the engine warms up to normal temperature, if one of them is cold, thermostat isn't opening up. Should open between 180-194 I think is OEM.

 

the heat-exchange line in the cab bypasses the thermostat...

 

I would swap the thermostat

 

The lower radiator hose is definitely cold and the upper is piping hot.
Looks like I'll be changing the thermostat this weekend.
Thanks.