hi
i have a 86 z28. i just put a 350 in my car and when i ran it the electric fan doesnt kick on. i had this porblem with the 305 but i wires it to work when the engien kicked over, i dont want to do that any more. can anyone tell me what kicks the fan on, and if there are relays or a sensors, tell me where they are located. as of now all i can see are the two sensors on the passenger side, one in the head and one in the bottom of the block, then i also have the thermostat, and a sensor in the head on the driver side.
the car is carb, if that helps. please help.

 

If it a single fan then it is controlled by a fan switch located on the passenger side of the block. It can be identified by it being a solid brass fitting with a single wire. Not to be confused with the anti-knock sensor which is larger and more round. This switch senses the coolant temp and triggers the fan relay to turn on the fan. Find your fan relay and look to see if anyone has spliced a wire to it, or if someone grounded the wire from the fan switch. Many people put in manual control or hardwire a ground to keep the fan running because they are unable to troubleshoot a problem with the fan control. A Chilton book is sufficient to follow the wiring and solve your problem.

 

manual switch here. when i bought my car there was no wire going into the switch in the passenger side head. my fan would work sometimes and sometimes it wouldnt. i guess i couldnt troubleshoot the problem but i am happier with the switch i have now

 

nevermind...i didnt see that the original motor had a carb.

 

how can i identify, the fan relay? i have a chilton book but the diagram is not too helpful. today i tested the fan and it works when a positive line is hooked to it, so i cant tell if the sensor, or the relay, or the pig tail is bad. if someone can help me find the relay.

 

It sounds like the Fan Switch is bad, just replace it with a Jet Fan Switch from Jegs that turns on at 200* instead of the factory 220*. Here's a picture of it on my 91 RS.

 

He says he had this problem with both engines. Did you use the old fan switch in the picture GKK sent or did the new block come with one and do you remember hooking it up? I'll give you the festest way to figure this out, but you will need 2 people. Get under the car and take off that wire going to the switch in the photo. It should be a female connector. Use a finishing nail or something similiar and put it in the connector after you have removed it and then ground the other end of the nail using a jumper or just touch it to the brass shell of the switch. Have the assistant turn on key but do not start engine. Then touch it on and off from the fitting shell or any decent ground. Have your helper listen for a clicking sound around any of the relays in the car, if you put your fingers on the top of the relay you can feel it activate. That will be the fan relay. They can be located on the firewall with several other relays lumped together or up front near the radiator below the cap. If you get a clicking sound and no fan operation then you can assume the relay is bad. If the fan comes on then most likely the fan switch is bad. I have worked on many cars with fan related problems, and I can say with alll assurance only about 1 in 10 ever has a bad switch. The switch in these cars only controls the relay coil, no fan power actually goes through it. Thats why the use a relay. Hope this helps.