Okay the water pump and thermostat is fine I know my coolant temp fan isn't working. My ac fan does work though. So half the radiator has a fan working just fine but still overheats sitting in the drive way any ideas ?


Also is it okay to simply bypass the heater control valve by running straight to the radiator. Pic below

 

I fought over heating for three years on a 350 4 bbl. 84 Z-28 before finally installing the 2 row aluminum radiator. Really appreciate the spell check. Thanks

 

I have never had a vehicle simply overheat because one of the two fans wasn't working. It's driving me nuts at the moment. I will eventually put an all aluminum radiator in, but for now it's not in the budget. The only thing I can think if to do is get the other fan working and see what happens.


What spell check are you talking about?

 

first replace the radiator cap. it will fail by allowing the system to boil over at lower pressure.

 

"I know my coolant temp fan isn't working."

Well, it needs to work. Without it, you'll have overheating.

 

Yes i am looking into the cause but there is another on their as well that works when the ac is on and it still over heated

 

Yes I am looking into the cause but there is another on their as well that works when the ac is on and it still over heated just sitting not on the throttle at all. I have had several vehicles with only 1 fan not overheat.

 

OK....good luck with that.

 

it should not overheat at idle with one fan running. yes, you need to replace or repair the broken fan. yes you have another issue as well.

 

This is a longshot, but the previous owners of my car had a manual fan. I replaced the radiator after it cracked for an all aluminum one, yet it would still overheat. The problem?

The wires were reversed, which actually made the fan spin in the opposite direction AWAY from the engine. I have been fine with a single fan ever since we swapped the wires around. Simple, but we overlooked it.

 

At what temp does your current fan come on?

For troubleshooting:

Turn the AC on...Do both fans come on when you turn the AC on? If both come on, then the circuit itself and the fan is good, and most likely you have a relay or Switch issue.

Both fans ARE supposed to come on with the AC.

IF the fan does not come on with the AC switch...have you run power to the fan that doesn't come on? Short power to it strait from the battery. Does it turn on?


IF the fan turns on with the power shorted to it from the battery, swap your fan relays by the firewall. Does the previously dead fan turn on now? If so, that's your issue. If it still doesn't turn on, it may still be "part" of the issue but then you have a deeper problem. Make sure you swap the relay's back.

I'm making the assumption here that the fan that doesn't turn on is your "secondary" fan run by the Fan switch.

Also, look on your passenger side head, almost strait above your dip-stick. there is a switch there, I believe connected to a green wire. IS that connected?

Down on the bottom of the block, is your Knock Sensor, this is NOT what I'm talking about. The switch is in the head.

 

Okay currently What I have found out is that when i had my AC on the passenger side fan would turn on only.

I bough tan aftermarket fan relay kit and it is currently installed and working. Both fan now turn on around 180 or when i have the ac on.

I will be testing the Coolant temp switch and the relay this weekend. As I would like it to be back to stock eventually.

 

As long as the fans are not on the same circuit or engaging at the same time around 180* sounds nice.

IMO, that and a 180* thermostat should keep the car between 180* and 200* and will give you plenty of room for slightly higher temperatures in traffic/etc.

 

Temp currentyly runs anywhere from 190 to 230 or so on the interstate, the aftermarket relay doesnt give exact temp just a little turn ***, but for now im happy with it. Now to find out the root of the original problem.

 

As long as your temp. gage is on you can set that style adjustable fan controller like this.

Turn the controller **** all the way to the end clockwise. (its highest setting).

Start the car and idle it until the gage is at the temperature you want.

At that time start to turn the fan controllers **** slowly down until it kicks on the fan and stop.

Its now set to that temperature to come on.

Usually about a 10* difference between the on and off cycle.

 

Turns out that the oil cooler lines were clogged and slowing the flow of coolant to a crawl. Once I bypassed the oil cooler and got the fans running it no longer over heats.