I've had a problem with the fan not turning on....at least that's where it started.

I tried everything I knew of trying to get the factory system to work. I tried 3 different switches, to no avail. But if you take the wire off the sensor and ground it, the fan will run. But for whatever reason, when the wire is attached to the sensor, it would never see the ground, and it would not start the fan.

So I got an aftermarket fan wiring kit that has a probe that goes into the radiator. Worked for a little while, and started to become unreliable. It got to where the fan would turn on most of the time, but other times it wouldn't.

So I got a different brand simular to the first with a probe. This one was supposed to be "adjustable" from 150 degrees to 220 degrees...but since the day I installed it, it woud barely maintain 220 at it's lowest setting. Now it doesn't turn on the fan until 230 degrees, and my temp gage stays right below the red line.

Now I guess I need yet another one...this time I think I'll get a Derale with the screw in the block sensor and see what happens. This is gettin real frustrating to say the least!!

I'd really like to get the stock system working properly, but it hasn't worked right since I've had the car...

Any one know if the Derale is a decent fan control? I'm open to any suggestions that will get this thing working reliably. I don't want to hook the fan up to a manual switch either.

I should stress that this is a single fan, non ECM controlled (1983) system.

 

What type of switch, stock replacement or aftermarket? Stock ones don't come on until 220-230 degrees. There is a post in this section with a bunch of part #'s and what temp they come on. This is the switch in the pass cyl head, correct?

https://www.thirdgen.org/techbb2/sho...hreadid=260999

 

It screws into the drivers side block, under the head. I tried factory replacements (3 of them), and none worked. With the stock system, the car would overheat. I'd watch it till it got up to 240 (just below red) on the gage, and I'd have to pull the wire off the switch and ground it so the fan would run and cool the car down.

Thanks for the link, but if I can't get a stock switch to work, I doubt any switch would help.

 

Driver side block? What happened to the one that is in the passenger side cylinder head?

 

Yeah, you might be right Stekman, I presently don't have the fan switch installed, because as I said above, I've been running the "probe" type sensor in the rad core.

Regaurdless, when I did have problems with the stock system, the sensor was screwed into the stock location where it was in the coolant flow. That could be the thermostat housing, water jacket etc...

Only thing I presently have screwed into a head is the temp gage sender in the driver's side.

 

If it works when the wire is grounded, try a different, lower temp switch. All the switch does is ground out the relay. All the ones I have seen are in the pass cyl head. Again, the factory ones come on way to hot, and if your gauge is off a little (might be 225 when it reads 240) the factory switch might not be ready to come on yet.

 

You're not putting any form of teflon tape or anything on these are you? IIRC, they ground out through the sensors contact with the cylinder head. I may be wrong, it's been a few months since I've actually used one in my engine.

 

Yeah, that's how I thought the system worked, but it's just unreliable..the switches just don't ground all the time. But I see what you're saying about using a lower temp switch - and it might work, but to be honest I like to be able to adjust the turn-on setting that the aftermarket switches allow. BTW, I tried installing the switches with or witout sealer and got the same result.

So I ordered and just recieved a new Derale unit that has a screw in the block type probe instead of the radiator fin type probe. But I wish Derale supplied a longer probe wire though. It only came with a 18" wire which is not enough to get the relay away from the heat. But they say in the directions that the wires "may" be extended - more connections that can go faulty...errrr...

I'll report back on how it works...

 

So all isn't well.....

I install the probe, wiring and relay. I installed the screw in pickup into the thermostat housing. Directions say it's factory preset to 160 fan on. Also suppse to be adjustable from 150-220 degrees.

So I start it up and let it warm up at idle. I notice it's been 10 minutes and the fan didn't start. Look at my temp gage - says 220 - and rising.

Then I go under the hood and checked the upper rad hose. Didn't feel like the thermostat opened yet - didn't feel any flow and wasn't hot - (it's a 180 degree stat) - it should have opened already.

Temp climbs to around 230 on the gage. T-stat finally opens, and fan starts shortly after. I look at the gage again....climbed to 240!!

Fan still running, temp slowly...slowly started dropping to around 230ish and hung there. Fan ran never shut off once it started. I shut it down and nothing boiled over but there was a good amount of heat from the engine.....this is frustrating. I guess I'll need to hook up a aftermarket temp gage up to see if the factory gage jives. And maybe replace the T-stat again although this one is practically new....

I just can't believe another fan control is defective along with a T-stat at the same time...

Any ideas??

 

You might want to get a cheap mechanical gauge, install it in the pass head, and verify that your temp gauge in the cluster is reading accurately.

 

Yeah, I think you're right...

At somewhat of a risk, I decided to take it out on the road and just see what happens. Never got above 240, and ran great. Had it out over 1/2 an hour - no probs. It's gotta be the gage.

If the switch is factory set at 160, that would explain why the fan doesn't shut off with a 180 T-stat. I'm thinkin this factory gage is maybe 40 degrees off....

But I can still turn 'em.....at a 15 mph roll!! .....in 2nd! lol!!

 

Well, I think I got it nailed now. Decided to loan out a heat gun from work.

It's got kindof a laser pointer, I pointed it at my T-stat housing - it gives you a digital readout down to a fraction of a degree -it's pretty darn accurate.

Found out that at 180 actual, the T-stat was OK because it started to open right at around 185. But my dash gage reads 225. At 190 actual, the gage reads 230!! So it's around 40-45 degrees off....so until I get another gage, I guess I'll just have to remember that I'm not really hot until my gage reads 260 or above...

I set my fan on setting while I was at it. On at 200, off at aound 180. Thirdgen stock gages are junk....at least the 82-84 are.

 

Is it the gauge or the sending unit in the head?

 

Unfortunately, I think it's the gage itself. This is the 2nd one I've tried, and it seems to make no difference at all. - But they are Autozone replacements so...

I may try another one anyway since it's easier than ripping the dash apart.