Me and a buddy just flushed the radiator and installed a 180 thermostat on his 90' LO3 Formula. We drained it first, then ran a hose through it and flushed everywhere but at the manifold and then installed the new thermostat and sealed it back up. after filling it back with coolant and running it, we noticed that the once working engine fan no longer goes on at all...not even over 220 and certainly not at 180. I have a feeling the thermostat wasnt placed in properly or something like that but im just not sure. Also, the radiator cap is a Autozone one, im not sure if that matters either. Any advice would be great, we just want to get this thing on the road.

 

I would make sure that the plugin for the fan is not loose. Also i would take the temp. sensor and replace it. It is probably dirty from old coolant. If you think you installed the thermostat wrong, then I would reinstall it. Usually the package has a picture on it that tells you which way to palce the thermostat. I would also drain the radiator again a put radiator flush in it and run the engine for how ever long required. This will flush the manifold and the block, not to mention removing deposits from the radiator. Which plain water will not remove.

 

You might also look at the fan relay. I've heard these go out too. From what I've read it seems to be fairly common. The thermostat will only open or close acording to coolant temperature. The fan is turned on by the ecm. The setting for the temperature the fan turns on and off at is programmed.

 

You need to burn a new PROM or get a chip to make the fan turn on at the right times with a lower temp t-stat. Until then, its going to do some funky things. See if you still have a problem after that.

 

if all else fails with the fan thing, and you make sure the fans are good, perform the fan mod, which you can find the procedure for in the tech section. heck, its a good idea to do this even if you do figure out the problem and fix it. good luck! oh, i forgot, what shape is the air dam in? if it is broken or missing, ill bet the farm that is your culprit!

 

You can unplug the AC stuff, then turn on the ac, fan runs all the time, mine doesent turn on by itself either.

 

Something that caused my car to overheat was leaves caught between the radiator and the ac condenser. I would pull the upper radiator support off and see if there is a pile of leaves caught in there. That will cause the car to overheat too.