Hi guys.
I have read like every post on here regarding this issue. I have a 2003 G35 Sedan with 162k on it. I bought it a couple weeks ago. Drives great but overheats in traffic with AC on. I can drive an hour or more on Highway and temp doesn't budge. I can let it idle in driveway forever and no overheating. I have cleaned radiator and condensor from outside and flushed fluid. Changed radiator cap and thermostat. Parked on a steep incline and bled system bc I didn't have hot heat at idle. Now I do. I listen to fans and they are going hi/lo. Tested clutch fan with magazine and it doesn't slow down. The hoses are very pressurized and super hot on top of radiator and bottom. Shouldn't top be cooler than bottom? I let the car idle with radiator cap off. No bubbles. No loss of coolant. I don't think water pump. No leaks and super hot heat at constant temp. The exhaust has no smoke or water. This thing is driving me nuts. Any ideas? The coolant overflow reservoir has alot of black crap in it, but when I drained it was green. I did oil change and no mayonnaise. I did however check transmission fluid and it looks like oil. More Brown than red and slight burnt smell. The transmission shifts smoothly and runs great. Should I begin to drain and fill 4 quarts at a time or is this car gonna break the bank?

Thanks,
Michael

 

the trans fluid can be normal especially if there are a lot of miles on it. i would check here http://www.nicoclub.com/FSM/G35/Coup...5_Coupe/co.pdf

to see if you can figure it out and maybe to bleed the radiator according to the FSM. maybe its just a bubble.