Coolant leak and engine overheating
 

Hey Guys ,

I Have an Infiniti G37S Convertible , my car is in excellent Condition but there is a small phenomenon that i cant understand , when i stuck in traffic under the sun for 30-40 minutes with AC is on or when i park the car under the sun with moving it while its running and the AC is on, the car drop all the coolant from the cooling system ( if you look below the car it is like a tap open below the car ) and the water in the expansion tank will start boiling , in the same time the car will not loose one drop over one year period if you avoid above two situations .

by the way I live in Dubai, the temperature here can easily reach 50 C during the day

any body knows what could be the issue .

Sounds like you have a major leak in the system that's triggered by high pressure caused by hot temp issues. My guess is your radiator has cracked somewhere or you have a bad hose or loose clamp that lets fluid out when the pressure gets high. A pressure test of the system will identify where the issue is if one of those turn out to be the problem. Other possibilities are the fans are going bad, the water pump and/or thermostat are bad but those wouldn't cause such a big leak, just frequent overheating. Take it to a shop for a pressure test or do one at home if you have the means. When you find out the what the problem is post it up here for others to learn from. GL getting it solved and fixed.

Pressure test it, like Blue said. I thought I had a leaking hose or bad cap until I pressure tested my system and found a big crack in the rad. Most autoplaces will charge you to rent the tool, and then return all your money once you return the tool. My leak didn't show until there was about 14 psi in the system.