possible overheating problem

[fred79]

I have a possible overheating problem the gauge will run way past normal under heavy stop and go or idling. I have seen the fan come on but alot of the time while it says that the heat is inredably high they aren't on. so I thought the fan wasn't working so I bought a fan control relay with a seperate sensor and the fan still didn't come on. I have already replaced both the temperature sensors and the thermastat twice. usually as long as I am moving it stays under the top of normal but if I stop at a redlight or have to stop and idle, it runs all the way up and takes along time to come down. I thought maybe I had air so i've tried purging the system. I just finished flushing the system and refilled with fresh coolant, and changed the thermostat again. I have also changed the rad cap, so i have changed everything but the radiator, what could possibly cause this I checked oil and found no foaming, and there was no oil in the coolant I removed, so I don;t think its a head gasket.
i used a sorenson sensor could I have bought a bad temp sender?
any ideas?
thanks

 

[NotSoSlowSHO]

Troubleshoot the actual fan(s) first. I had a similar problem last summer. As it turns out, the brushes in the fan motor itself were worn completely away.

I would first run a couple of jumpers directly to the fan motor to make certain that the fans are simply not worn out. They are brush motors, and the worn brushes are the most common types of fan failure for these fans.

Run a couple of jumpers directly from the battery to the fan(s). If they instantly turn on, without having trouble spinning up to speed, then you have a problem elsewhere.

 

[fred79]

I did jumper the fan it works fine, thats why I used the relay I thought that the ICCM was not unctioning right so I install a fan control relay with its own radiator sensor, what I was saying is that I connected it and the fan didn't run anymore often. It seems that since I flushed the coolant it is running better but still tends to run near the top of normal when I run hard and some times exceeds normal still. If I idle for any period of time that is when I have problems I have also noticed that if it runs off the scale and I rev the engine it will drop back into normal. I have been thinking of two things that may be causing this first is that I may have over tightened the waterpump powerstering belt, also I used teflon tape on the threads of the temp sensorand since it is a single wire the tape may be causing a diversion in the measurments. I will try to get rid of the tape tomoorow and loosen the belt some. anyone know if I am over looking something?