The electric fan is not kicking on when it gets above 220* on my '87 2.8. I am certain the guage is accurate, I have replaced the fan switch sensor and also tried 2 used ones. When I ground the ALDL diagnostic terminal the fan will come on, however, telling me that the relay should be good.

Any other ideas why the fan isn't coming on and cooling the engine down? It ALWAYS used to come on at 220* and stay on until it cooled down to about 180*

 

i have an idea for testing your new fan switch. do you own a testlight? good. take it's ground clamp and hook it up to battery hot, yes you read that correctly,, hook it up to battery hot. now poke things, you will notice it is now a ground tester.

now touch the lead coming off the temperature switch in the head. does the light come on? it should not. now turn the engine on and let it heat up, keep the light on it until it gets to where you feel the fan should come on. did the light come on? if not your new temperature switch is bad. if it did come on that ground wire that grounds the relay has a break in it somewhere. find it and fix it or replace the wire.

also while we are talking about it, what did you replace? was it this thing? (worst picture ever, i am sorry. it was the best i had on hand)

 

make sure u flushed ur system good u may have air pockets still.

 

Think I found the problem last night. Started the engine and grounded the wire to the sensor and fan kicked right on. I guess the brand new sensor is no good, since it isn't closing the circuit inside when the engine gets to 220*.