Seems odd the efan would come on when the heater is on......the efan should come on whenever the a/c compressor engages or coolant temp reaches 218F. The sensor back of head/drivers side is for the temp gauge, the sensor in the t-stat cover signals the computer.

 

I replaced the one at the back of the motor for the temp gauge, so either of those could be bad as well as the fan, hmmm

 

Sounds like when you're turning the heat on you're circulating the coolant and activating the switch. The coolant from the heater returns through the thermostat housing. Your engine may be running much hotter inside then you think... I think you may have an air bubble or blockage in the block or both. Is your thermostat currently installed?

 

Thermostat is installed, if I unhooked the connector on the t stat housing will the fan come on and stay on? If the system is not grounded would the effect the operation of any of this

 

I think he is referencing the aux fan for additional cooling when engine temp is elevated above normal operating range or when the AC is on.

 

Uh huh... the fan isn't coming on without the heater on.... sounds to me like coolant isn't circulating through the thermostat housing from engine.... I think out should make sure the thermostat isn't backwards... that's pretty common also.

 

Negative, the coolant from the heater core returns to the motor thru the water pump. Heater core receives water from the t-stat housing.

 

Guess that makes sense.

 

Sounds like a crack in either the head or block. Does the engine blow bubbles at the radiator fill with the cap off and system filled to the top? Also, T-stat only needs a 1/64' steam hole. Too much circulation runs HOTTER the coolant needs time in the radiator to shed heat.

 

Second that.

It's critical to get all of the air out of the system. Park it on an incline to raise the radiator higher than the rest of the engine, and let it run with the cap off. Add your 50/50 coolant/water mix as the level goes down. Sometimes this takes a while, but as long as you're seeing bubbles come out, keep it going.

 

I am running straight water no coolant, no bubbles in radiator fill, no water in oil, I ran it last night for awhile it stayed around 210-220 till I moved the heater on then it got hotter, I don't know if I had the heater valve hooked up right, the e fan doesn't seem to work like y'all say it's supposed to, the heater valve got broke so I won't know any thing till the weekend so I can get a new one. There is water coming out of the thermostat housing I took the top radiator hose off to see, and with the t stat out it runs between 150-200