I'm at a loss with my 2003 G35, few weeks ago car was over heat, coolant boiling and flow out reservoir, refill coolant bled the system, drive about 40 miles everything fine but noticed coolant rise 3/4 in the reservoir ( min level at start). I decided to replaced water pump , thermostat, radiator cap, upper and lower radiator hoses, bled the system drive about 40 miles coolant rise 3/4 in the reservoir ( fill min level ), pressure test coolant system everything ok, thinking might be bad thermostat so I remove it , now driving without thermostat temporary for now, drive for another 40 miles coolant rise 3/4 in the reservoir, I know if I drive few more miles it will overflow out reservoir. I check coolant there no oil, check oil there no coolant, thinking could be blow head gasket I decided to add Seal-Up liquid glass , let car idle 20 mins and let it cool, idel another 20 mins. let engine cool, did this 4 times, went for test drive coolant rise almost to the top reservoir after 40 miles, car never overheat but i'm sure when too much coolant flow out car will overheat. Any idea what I should do next.?
Thanks

 

Sounds like air in the system, what caused it initially would be my concern, but what is your procedure for bleeding the vehicle?

 

Does your heater pump out scorching hot heat? If the heater is still blowing cold air you definitely have air trapped in the system.

Did you pressure test the coolant loop AND the radiator cap?

If all those things check out the next step would be a leakdown test to see if bubbles come out of the radiator.

 

Heater pump out very hot heat, but after 30-40 miles of driving coolant go to reservoir then I lose heat due to coolant loss, I rent Radiator pressure tester at Autozone found no air leak, test brand new radiator cap for leak found no leak. My 2003 have clutch fan and 1 condenser fan, I'm going to check if condenser fan work or not, can you tell if condenser fan come on when I turn on AC even when engine cold, or do I have to wait for engine to warm up.

 

The electric fan will turn on after the engine has been running for about 30 seconds if your AC is turned on.

You can test the mechanical clutch fan by trying to spin it while cold, then trying to spin it while hot.

It should be sort of stiff and not able to make 1/4 of a turn when you try to spin it while cold. It should be VERY stiff and difficult to turn at all when the engine is hot.

 

Electric fan and clutch fan both works fine, radiator 6 years old, probably my next step is to replace radiator, after that out of option .