Doing some upgrades to my 86 (built 4-23-86 ). I want to put a 160 stat in and change the fan on temp as well, I ordered ( V01 ) heavy duty cooling when I ordered the car so it has a bigger radiator and a ( B4P ) pusher fan in front of the radiator as well. In searching this forum it seems that some say you have to change the fan on sensor or some say that you have to do it by re-programing the ecm. Which is it? Or is it both? I have a SuperRam to put on it as well as TPiS headers and Y pipe and am changing the mufflers to something a little less restrictive. I am going to delete the air pump as well just to clean up the engine compartment. I would like to change the cam......just can't seem to make up my mind. Would love to change the heads but I think I might wait for that. It's an auto car so I have a D44 3:45 sitting on the bench to install as well just in case I do some future mods.
Thanks
Joe

 

The ECM turns on the main fan, the temp switch in the head turns on the pusher. The pusher doesn't really do a lot though. I put a 160F thermostat in my '87 with a 195F temp switch to control the main fan relay instead of the ECM. I then used the ECM relay to turn on the pusher. I've never seen it over 210F even sitting in traffic with the A/C on.

 

I would like to do that as well. I have a 160 thermostat and a low temp on switch making the auxiliary fan come on sooner. How did you switch the relays making the main fan come on instead of the auxiliary one with the temp sensor?

 

You all need to remember that this C4 Corvette "needs" the higher temperatures for the emissions to run cleaner. You can't take a Corvette designed to run at 195-215 degrees and make it run cooler by simply adding a cooler thermostat. The cooler thermostat will just stay open after startup. To change the fan operating numbers requires a new prom for your computer which is not that hard.

I have the B4P Auxiallary Fan on my 1988 C4 and it has been a blessing in this Hot Humid part of the country. It is activated by a switch that goes to ground between cylinders 1 and 3. The connector for this particular switch looks like the one used on the knock sensor. On my Corvette I have it on a manual switch and it stays on all summer long around Northern Virginia.

Cleanliness is CRITICAL for a good cool running Corvette! Clean out the space between the radiator and the condenser every year or install a screen down near the bottom of the gap. I also remove any oxidation from my aluminum radiator and Condenser using "Coil Cleaner" or if you are a welder the aluminum "surface prep" spray will remove all the corrosion leaving aluminum to transfer the heat.

Last but not least be absolutely sure that your Corvette has the Air Dam under the nose of the Corvette. It's job is to force even more air through the radiator getting rid of more heat. If your Corvette is missing the air dam you will know it...

To help Hot running Corvette I encourage people to verify that the EGR valve is working properly. The EGR can fail and when it does the engine runs Hotter and the potential for detonation is greater. On a C4 the EGR is very important and it requires maintenance. The EGR can not be disabled properly without making a new prom for the computer as well. I like to verify that it is working at least once a season I test it with a Vacuum pump.

Having the right ratio of anti-freeze to distilled water can also lead to engines running hotter than normal. 50/50 is what most use around this area. I use 70% distilled water and 30% distilled Water which allows the engine to get rid of the heat.

Be Well and Stay Well!

 

I installed manual override switches for both fans so I can turn them on and off whenever I like. Super easy, cost me like $5 for the switches, the rest (wiring, quick splices, tape, etc) I had around the garage. Used this vid as a reference:

 

ECM grounds the main fan when coolant hits 228F, you can manually wire that relay to ground via a switch. Do not be dumb enough to set it to run all the time, as its actually a detriment to cooling when the fan runs over about 35-40mph or just because you want it on at 185 or something silly. Turning it on at 200 or 210 is low enough. The car will never run at 160-165 Coolant temp unless its January anyway.

The alternative is have the chip reburned and just change the main fan setting. ECM does not control the front B4P fan, which naturally comes on at about 10F over the Main fan in most years.

B4P option, you can just change to the hypertech switch that goes into the cylinder head, available from MidAmerica/Ecklers/etc. and that will turn the front fan on earlier to push air through the condenser and radiator from the front. I'd recommend doing that before the previous.

This all assumes your tstat is working and the space between rad/condenser is cleaned.

I have done all the things above to make the C4 run cooler, including upgrading WP and radiator, the best bang for the buck was a DeWitt radiator.

 

I thought the Hypertech fan switch caused the main to come on early? Not sure it matters as it appears to have been discontinued. 🙁