Hey guys, my G35 overheats at about 25-30 mins of driving. I've replaced the thermostat, radiator, radiator fans, coolant temperature sensor, radiator cap, water pump, did a head gasket test with the blue fluid which it passed, and got the whole cooling system vacuumed for air. At idle the car blows cool air with the heat on, but after driving the temp gauge goes up, and if I floor it the gauge goes back down and I get heat. There is coolant being shot out of the overflow tank because its hot. I haven't got the system vacuumed again since doing the water pump which I did yesterday. Could there still be air from doing the water pump? Any help would be appreciated. I've had the car for 7 months now and haven't had a problem until now. It's been a whole month of the car overheating and me replacing these parts and I haven't driven it far within this last month.

 

Did you use the proper coolant?
Did you use OEM Infiniti parts?
Are the fans turning on at the proper temperatures?
Did you closely follow the troubleshooting steps in the FSM?
Does the vehicle overheat with the radiator cap off when starting from cold and does any air burp out?
Is anything blocking/restricting air flow in front of your radiator?
Are you missing the fiberboard shroud underneath your vehicle?
Any mods?

Telcoman

 

I used the proper coolant, however every part replaced has not been oem. The fans are turning on, I haven't been able to check the air burping out of the radiator since changing the water pump yesterday. The shroud is where its supposed to be, no mods. The hose coming from the motor is hot but the hose coming from the thermostat is cold. It could be that it is not opening however this is the second thermostat. I replaced the OEM one and that was not opening so I put in this one. That was done the same week. What are the chances that there are two bad thermostats? Thats why I figured it was the water pump and that was a hassle due to the timing chain.

 

Definitely sounds like you have air in the system. I've burped by popping open the cap while cold, alternating squeezing the two large hose (facing the engine from the front, top left of radiator, and bottom right of radiator) to get some bubbles out, then getting the car slightly warm, verrrry slightly popping the cap and letting some pressure out as well. The actual burping procedure never worked for me, but your mileage may vary. Make sure the overflow tank is filled correctly to make sure you get a vacuum when the car is off.

If that fails, make sure test your thermostat, it may not be opening at the correct temperature. I'm not sure of the procedure, but it should be easy to find.

 

Idk you've already replace the most important parts or the parts I would replace. I had a similar problem, my radiator cracked but I never let it overheat. I replaced the radiator, bled the system of air and everything now is fine.

 

Try to bleed the system of air again. Squeeze the upper and lower radiator with the coolant cap off while the car is off and open the bleed valve in the rear upper part of the coolant system. It's a top coolant hose in the rear of the engine with a bleed valve. Do this until no more bubbles and the coolant stops dropping. Add coolant when it drops.

 

Same problem here , I got a 04 coupe too and I'm losing my head trying to figure out what's going on, when is hot is shooting the coolant to the overflow tank

 

Most likely you need to do a better job purging air from the system. These cars are a b%tch to flush without trapping coolant. Even professional mechanics screw it up like half the time.

What I do is lift the front of the car a bit when filling it and veeeery very slowly pour coolant in. I'm talking like painfully slow. I also try to avoid ever draining the block completely, and just do a few flushes with the radiator by using clean water in the radiator and running it until it warms up and then draining again. I usually do this like 3 times and then fill the radiator with a mixture of like 65% coolant to 35% water for the final fill (where the extra % of coolant should hopefully mix with the pure water still in the block and eventually come close to evening out). This helps avoid getting air in the block from draining from the block drain.

 

I get the front on jack stands when filling, leave the heater hose bleed valve open until coolant comes out, put the bleed back in and top it off, run the motor on jack stands till it's warm with the radiator cap off. Lower the car, test drive around the block with it warm and rev the **** out of it. Go back, cool off, top off coolant and usually good at that point.

 

Proper bleeding, also set the heater to 90 and high fan while doing all that to get any air out of the heater core.

 

Yes that part is SUPER important.