Well, I took mine to the shop and it had a crack someplace in the system that expanded when heated, draining all of the coolant into the overflow basin.
$251 and 3 days and I should have her back good as new.

SOF Vette

 

If you have the Automatic HVAC, with the digital read out, try this to verify gage accuracy...

Push both fan buttons until -00 shows on the readout.
Using the right button, scroll up to -16 and push the 'auto' button in the middle.
This should show you the temp, in Celcius, from the CTS.
Convert to Farenheit and compare to your gage, which no doubt, is woefully inaccurate.

 

Well, I am experiencing a similar problem. After repairing a leak in the intake to head gasket and replacing a bad injector, the engine was running great. Until....

After going for a drive with the top off (my car not the wife!) I pulled in the garage to find the temp going through the roof and the coolant overflowing. It had been fine on the road but doing a short city drive overheated. Dang.

Neither fan was running. They wont run while in the diagnostic (grounding the diagnostic ports) mode. If you jump A and E, they work. I obviously have power to E so the inline fuse is good and so are the fans since they both run. Depending on how you read the haynes manual (these manuals leave something to be desired) if the fans work when you jump A and E then replace the relays. Course, that didnt work. It also says to check D by grounding it. If the fan doesnt work check the fuse (which one?) and check the ignition wiring. What wiring? The wiring diagrams I have dont show squat.

I should have mentioned it's a 91. Also, I've already replaced the coolant sensor (for the ECM) but not the gauge sensor which is located on the ride side in the head. My understanding is that the ECM controls the fans based on the coolant sensor only (front of the intake). I'm thinking I'm going to a straight manual system on this pig.

So...any ideas?

 

Brother. Finally went through the corvette owners manual to see if it had anything. In the service section under fuses, you find in position 9 about twenty things under one 10 amp fuse, along with the fan relays. Amazing what a new fuse will do. Not sure why it popped so I have to look into that but at least I know where it is and they work again.

Its tempting to set one up that bypasses the ECM. That way at least one will work if the ECM gets confused. Makes sense there would be a spot avail on the left head as the heads are interchangeable. They should have put the gauge sensor on the left side just to make it easier to get at. The right side is a real bite.

 

get to know the locals in your area, with the right equipment the fans can be reprogramed in the ecu in a couple minutes. mine are set to come on at 150 which is basically always running. one of these days i'm going to a 180/190 on the primary and secondary.

 

Hey Guys,

I just purchased this kit from Ecklers - "Corvette Low Temperature Cooling Fan Kit, 200º, GMP, 1984-1995"

https://www.ecklers.com/product.asp?...0&dept_id=1748

I will let you all know how the install goes, and whether or not it works! By they way, anyone have experience with this kit? Your adivse or input would be appreciated. THANKS!

 

I have used that switch, not the whole kit. I would recommend you just hook up one fan to start. That way the fans are staged. You will need a socket IIRC 22MM. (Don't take my word on that). You can add coolant back through the overflow tank when you are done.

 

When I got my 90 several years ago I had a slight overheating problem. I put the front up on jack stands and tried to feel my way around inside the fan shroud. To my suprise it was full of leaves, some paper and other forms of road litter. I suggest to all new owners to make sure that the inside of your fan shroud is clean. Spin the fan blades as well to make sure there is no obstruction. This perhaps is the cheapest and most effective way to keep the cooling system working.

 

agree but would like to add that the radiator really should be removed and blasted out with air and a pressure washer. so much junk gets wedged in the fins that it creates serious cooling issues. also our cars are getting so old that $99 for a new old stock GM unit is really a good idea. heater cores and radiators fail constantly at 18 years here in the pacific northwest. water, minerals etc..

 

I could not agree more!!! I took mine out later and did exactly that. I found that straight Simple Green cleand the outside completely. I let it soak in for a while. It was a noticeable difference.

 

Hey Badduck, I am actually planning on connecting both fans. Currently, NEITHER of my fans will come on no matter what temperature the coolant is at. If I hook up only one fan, then the other will NEVER come over.
By the way, the Ecklers part number for the fan switch that I bought is 40290

 

be careful with compressed air. i had my radiator out of the car, and was blowing the crap our of the fins, and got the nozzle too close, and the aluminum fins bent over, and clogged the air passages in the radiator. it took about 5 hours to straighten them well enough I was comfortable installing it again. That was 3 years ago, and all is well.
Just be careful with that nozzle.

 

I installed the new thermal switch, and the fans are running as they should (on at 200, off at 185). I have them both wired to come on and off together. So far, so good! Very pleased!

I ended up making my own tool to get the water jacket plug out. I took a 3/8" drive extenstion, and ground it down to 5/16 with my trusty Dremel. I let penetrating oil soak on the plug for about an hour. It came right out! Did not need a breaker bar.

I spliced the wires to the "F" connector wires on the two cooling fan relays. Very easy install.

Looks like I have found a solution for my non-functional cooling fans. I will post again if I have any issues with this solution, but so far...It does the trick!!!