Radiator Fan Will Not Come On!

[jppatin]

Howdy,

On my '79 Spider, the radiator fan will not come on. I have replaced the switch at the bottom of the radiator, replaced the thermostat, and blead the system by the book, still no fan!!! I have jumped the wires, and the fan comes on so I know the fan motor works, it just won't come on when the water gets hot. What now??? One more thing, it's starting to get hot in Texas need fan asap!!

JP

[TulsaSpider]

So what is your temperature doing?

[jppatin]

getting into the red zone. Not good.

[So Cal Mark]

where did you jump the fan? Are you sure the ground is good?

[jppatin]

I jumped the wires where I unpluged the fan. If the fan comes on than the groung should be good right? a few weeks ago I cleaned th ground crowns that are on the side of the finder wells .

[mdrburchette]

How long does it take for your car to overheat in the red? Here are two possibilities that have happened to me:
1. I only got a short distance from home and the gauge pegged to red and the car overheated. The thermostat was faulty and wouldn't open

2. I replaced the radiator because of a leak and bled the system but when I test drove the car the gauge was showing hot. I bled it again thinking I had an air bubble but the gauge was irratic and still showing hot. An infared thermometer showed the head to be cool. The sender in the head was faulty.

[jppatin]

I can drive the car as long as I don,t get cought in traffic. At what temp should the fan come on? Also after I turn off the car the fan should stay on till for a while right? My infrared temp seam to match what the gauge was reading.

[mbouse]

i would not doubt you for a second. i appreciate the panic situation when you know you are overheating, been there, done that. however.....unless you are verifying that your temp gauge is accurate when in the red...by using your infared meter - - - it could, just might, possibly be incorrectly wired or faulty heat sensors.

i only say that because i read that you have done everything else to assure that there is no air in the system and that the fan does work, and that it is properly wired with a good switch and a solid ground. have you tested the hot wire to the fan with a volt meter?

the fan should come on above 195°F i generally run consistenly at 190, with no problem



so, your comment confuses me.." after I turn off the car the fan should stay on till for a while right" IS the fan coming on?

[jppatin]

That's what got me scratching my head too, everything was running fine last summer, fan coming on when it got to 190, all good. Then my water pump whent out in September '08, did not replace fan switch or thermostst at that time every thing seam to run fine through the winter mouths.

I noticed while stuck in traffic a few weeks ago my fan was not coming on, and thats when all this started.

thanks for help.

[mbouse]

Maybe i am dense... my family certainly thinks so.

the fan does or does not come on

[manoa matt]

Check your ground pod and connectors again. I cleaned my ground pod and a few weeks later the same symptoms you describe happened. Also when you gauge reads 190-195 take a infrared reading at the fan switch. It may be 190-195 in the head where the sender is, but may be cooler at the fan switch at the bottom of the rad. Of course you could still have an air bubble either in the top of the head or in the lower rad hose just under the thermostat. Installing a "t" flush fitting in the upper heater hose that comes out of the back of the head realy helps to get all the air out on the first try.

[Tappy]

i went trough some cooling probs myself lately , There where several things going on on the same time. Only thing i was kind of sure of was my waterpump as it was recently replaced. Themostat replaced (but had to drill a little hole in it to let out the air pocket. Installed a t-piece (like the ones in a flush kit) and filled her up All worked fine untill the engine cooled down completely then several thing went wrong. She sucked in air trough the radiator stop as it wasnt closing fully no more. Then all worked fine again until next cooldown then she sucked air trough the t-piece (engine mount) where i drilled in a hole , but didnt fasten the screw in there tight enough. Then she ran fine untill next cooldown then she sucked in air on the waterpump hose , where one of the clams was not tight enough (slipped trough) and a slightly to large hose from the pump to the thermoststat prevented the clams to close up


today i hope after running hot she will coold sown with no probs at all
ofcourse it also can be your temp sensor thats broke , or a bad ground

[jppatin]

Thanks to all who pitched in to help!

I got the problem resolved, I had the thermostat in wrong. Who knew!!! on to the next problem..

Thanks Again.
JP