JIMMvette

I have a 61' corvette. I just installed a new DeWitt radiator with a built on Spal fan. I wired the fan per the instructions but it has yet to start up at 185 degrees. The temperature sender is installed in the head. I can ground the sender and the fan will run. I have ran the engine for an hour and it runs cool with the fan running continuous. Does this sound like a grounding problem ? I have the fan ground wire grounded in one of the screw holes in the frame where the shroud was located.

Subfixer

Are you saying that when you ground the lead that is attached to the temp sender, the fan works? If so, sounds like a bad temp sender. Or, it's not the temperature range you think it is.

Most fan temp switches I have seen are not designed to come on until you reach about 200-210 degrees, then they stay on until the temp comes back down to about 170.

If you are using your temp gauge in the dash to make your assessment, be advised that those gauges can be off as much as 15 degrees (Old temp gauges usually read higher than actual temperature due to the quality of the temp sending units available these days).

Did the temp sender come with the fan or did you buy that seperately? If it came with the rad/fan, just call Tom and I'm sure he'll make sure it's working properly or he'll replace it.

Hope this helps.

andy60

I installed an electric fan setup in my last C1 because I built a 383/425hp engine for it. Thought it would need it. The fan setup was a big waste of time and never needed it. When I used the fan it ran to cool. Even worse I had to rework my generator and regulator to handle the load from the fan. I worked that out but what a bunch of work for nothing

Try taking the fan off...

my58

Jimmvette,

Is the unit you have one of the new fan / radiator combos with the shroud built in?

cbernhardt

Since the fan will run when you manually ground the sensor wire I would guess that either:
1. The sensor is bad
2. The coolant is not hot enough to turn the sensor on.
3. The sensor is not making a good electrical contact to ground.

Did you use thread sealer on the sensor? If so, this might prevent the sensor from making a good ground to the manifold.

You could check the sensor by taking it out, heating it in a pan of boiling water, and then check it with an ohm meter or continuity checker to see if it is closed.

magicv8

IMO your fan should only come on when the radiator temp rises, since the fan does not cool the engine. Derale makes a fan control that has a probe to insert between rad coils to sense rad temp. The temp settings on the Derale are adjustable, it will support 2 fans, and I wired mine to use the alternate fan line to light a dashboard indicator lamp (that tells me when the fan is running), since the fan is too quiet to hear.

JIMMvette

Yes,,,, When I ground the sender , it does work. I did not use sealant or tape on the sender. I am in fact judging the temperature by the car gage. I have the sender in the head and not in the intake. It was a radiator/fan combo which should not need a shroud. thanks everyone/////

0Tom@Dewitt

The standard switch we supply is a 195on/175off. It is not an analog device that you can measure ohms, it is simply a switch. Open or closed, that is it's only function. When the engine temps get to 195, it closes and grounds out and the fans come on. Since you manually grounded the wire, it sounds like everything is working but you didn't say how hot you let it go up. If you gave up at 185, then you'll never see the switch come on. It must go up to 195ish. Spal does also make a 185on/165off that everyone knee jerks to once they here the lower numbers but that doesn't meen you will run cooler just because you use a lower setting switch. The fans will come on at 185 but you will have to cool down to 165 for them to ever shut off and some cars just can't get there so the fans run forever. My suggestion is to let the thing go up to 200-210 and see if the fans come on, if not, then the switch is bad and I'll get you another one.

61iwon

I had the same trouble with my '61. I put the Dewitt radiator and a electric fan unit in it. Take it to your local shop and have them shoot it with the infrared temp gauge. Mine shows 220 on the gauge when it comes on at 180. The gauge is off.

I have blown a couple relays and not figured that out yet. I have some pretty good ideas what it may be though


Dave

STEVES59

I have played with various electric fan set ups in many different cars My general concensous is most fans sensors are designed to trip @ 220 degrees. I have had very good luck useing a 2 pin sending unit listed for a chrysler application That I found in a standard ignition catalog. Th catalog listed the switch active @ 180 degrees, I wish I rememberd the part number because it worked great and I have used it on 3 of my own cars as well as a few friends the only thing I can tell you is look in the standard ignition catalog under temp switchs look @ chrysler applications untill you find it, the head was round shaped I feel strongley this switch will resolve your headachs. I thing the part number may have been ts17 or 19 but dont hold me to it its been 15 years since I played with one

magicv8

Read my post above, and you will see the #16759 adjustable control at
http://www.derale.com/electricfanaccess.shtml that I use in my 66.

It works