350z overheat issue
 

i need some help guys my z cooling fans come on at idle (which is normal i suppose) but after that dont seem to turn off if i let the car idle is this normal???
my fans come on more than usual and car overheats randomly when stopped
today when i got to work i let the car idle and temp started going up so while parked in nuetral i rev it up to about 2000 rpms then noticed the needle went back to normal then let it sit idling and needle going up then rev it again and the temp needle goes back down??


so far ive replaced thermostat and coolant temp sensor nothing has changed and i tested my old thermostat in boiling water it was still good. ive bled the system with the spill free funnel and with the heater on.

can it be possible i do not have the right coolant mix 50/50 ratio right??

Needs a better bleed. You have an air bubble , make sure you bleed from the header hose fitting.

The coolant mix would make a negligible difference. Your problem happens with a failing thermostat, trapped air, or a deficient electronic fan.

keep bleeding...

You gotta keep bleeding it, its a pita on these cars when we did mine we had to hold it at about 4k for 2-3 mins before it finally pushed the air out

Yes +1 on the air, it takes a loooong time to get it all out. Just keep bleeding it. It will keep bubbling up in the funnel.

i had this same problem over the winter...i dont know how the air got in there in the first place, but I went through EXACTLY what you've done.

Changed thermostat, flushed, bleed...bleed more....bleed more.

Finally I gave up and thought it was the head gasket but, since the overheating was so random, I drove the car anyway. By the time I scheduled with my tuner to tear the motor apart to change the head gasket...the problem was gone. I assume the air worked itself out.

If you want to try something that I think worked for me while bleeding, here you go:

Unscrew your radiator cap about half way. To the point where you cant pull it off, and nothing will leak/spill out.

Now squeeze your upper radiator hose, and before you let go, screw your radiator cap back on tight.

For me, this pushed air out of the radiator into the overflow tank...then when you screw the cap back on, it will suck fluid back into the radiator.

Other than that, make sure you do what terrasmak said and bleed from your heater hose fitting.

Bleeeeeeeeeeed

is this ur frist time doing it? if so you know there is a bleed screw u lose it up to let the air out

to slow7, where is there a bleed valve to open?

thank you for the link.


I`m trying to learn on this forum so I can be semi-mechanical to do my own work. this overheating is driving me nuts and its a short trip! Thanks again

The factory service manual is also available online and is extremely helpful.

thanks for your help