i bled the system again this morning when it was cold and drove fine for ten minutes before overheating and the fans still wont kick on like an instance before when i did hadnt bled it correctly. you think its the headgasket??

 

Maybe a stuck thermostat?

Even if you bled it incorrectly, once the engine cools down just keep filling up the radiator until it remains full after warming up and cooling off.

 

shouldnt the fans come on regardless if the system is bled properly. the fans are based off the water temps. if temps get high enough , fan should kick on. try turning on the ac, the second fan should automatically come on then. if not, somethings up with your fans/relays/etc.

 

exactly, the fans run off the temp sensor on the head, if it's not reading or you have an electrical problem, the fans will not come on, they are unrelated to the thermostat

 

Incorrect, the fans turn on via the fan switch mounted on the lower portion of the radiator or if you turn on the AC.

If the system isn't properly bled, there is a chance your fans will not turn on. My guess would be an air bubble at the thermostat causing it not to open, thus no hot water circulates through the radiator which means no fans.

 

huh, well in that case, turn on the ac and see what happens. at least make sure the fans work. in aempro you can set them to be on all the time.

but in any event your system def needs bleeding, or new thermo. if it worked before you opened up the system, i would say it just needs more bleeding.

 

yes, and what runs the fan switch? I am thinking it's the ecu which gets it's reading from the ECT sensor mounted in the head.

As camuman posted the a/c also turns on the fans, so he can easily test it this way.

 

Nothing, it's a "mechanical" fan switch. The water in the radiator heats up the metal probe which sends a voltage to the ECU. Once that voltage hits a certain limit, the ECU turns on the fans.

The ECT in no way affects the fan switch. I have an AEM EMS, my ECT doesn't work yet my fans work perfectly fine.

 

well whats funny about this is you can set aem up to control your fans based on water temp. so that mechanical switch is not needed when aem is setup to control the fans.

i set mine to just be on al the time, but you can pick temps that they are on and off at.

stock ecu though must use this mechanical switch. makes sense, this must be wy people buy lower fan switches.

 

ah yeah, didn't think about that, I just know that with the aftermarket ecu's they all read the ECT and run the fans based off of that.

The EMS reads ECT it just doesn't display it on the dash, so that is how I believe the EMS guys can still run the fans without needing the dash display adapter from Modifry