I own a 1993 40th Anniversary 6-speed that comes close to overheating in the summer as I live in the desert southwest (115-120 degrees). The secondary fan comes on at 238 degrees and I want to lower that number to 185 degrees using a 1984-95 (C4) 185 degree Low Temperature Cooling Fan Kit. Has anyone made this conversion? The instructions refer to the “Factory Cooling Fan Switch.” The service manual refers to an “Engine Coolant Temperature (ECT) Sensor.” Are they the same thing? The instructions say it is located on the cylinder head between spark plugs one and three or six and eight. The service manual shows the ECT on the lower water pump housing. Connecting the secondary fan relay is pretty straight forward, but I am not sure what sensor or switch to remove. Also, assuming I remove the right one, will bypassing the ECM cause codes to appear? I own a Z06 too, but it does not come close to overheating in the summer. Can anyone help? ROGER

 

The car is operating normally. If you change the temp switch I would go with a 160 Thermostat as well. You will also need to get a matching ECM. Without the ECM she may run rich.

 

The easiest -- and proper -- way to alter the cooling fan on/off settings is to reprogram them in the ECM. Contact TJWong. He should be able to flash you a new EPROM that you can then install in your ECM. But I'd recommend you set the temps to:

Primary on/off: 205/195
Secondary on/off: 210/200

...so that your fans don't run all the time. If you want the fan settings lower than this, change to a 160* thermostat and set the fans to:

Primary on/off: 190/180
Secondary on/off: 195/185

The ECM controls the fans based upon numerous inputs (including Vehicle Speed Sensor inputs, etc). If you use a fan switch instead of changing the settings in the ECM, the fans won't shut off at highway speed, etc.

Live well,

SJW

 

there is no good reason to change to a 160 therm as stated by jngizzi, maybe he should read all the tech posts concerning this issue before offering bad info.

 

Like you I am a 93 owner from a hot weather state so I understand your concern. As the others have stated your fan and cooling system operation does sound normal, but we both know how scary it is seeing that gauge climb when it gets hot, I didn't like it either. I would agree with those who advise against the 160* stat and changing the fan if I lived in a cold weather state, it is no problem here in Florida.
I installed a 160* stat and the cooling switch you are considering, I did not want to pay for ECM tuning just to run the fans at a lower temperature, since my engine was nearly stock.
Those modifications reduced operating temperatures at least 20 degrees with no adverse driveability issues experienced. The cooling switch did cause my car to set code 28 (quad driver module circuit 3) that code should not illuminate the check engine lamp per the FSM and did not in my car.
My switch is installed between cylinders 1 and 3, there is a plug in that location from the factory, the temp sensor for the digital gauge is in the water pump housing, the one on the right bank is for the analog gauge, do NOT replace either of those with the low temp switch, it simply overrides the ECM control and that is the reason it sets code 28.
I have made more changes since and eventually had the ECM chip tuned to run my fans and have now disconnected my switch, the code 28 no longer sets.
PM if you have any other questions, have the instructions that came with my switch and could scan & fax them to you.

 

I changed to a 160 Thermostat. Where do I get a matching ECM? After reading the responses, I m not convinced the switch is the way to go.Thanks.

 

I would agree with you as I was stationed at Ft. Lewis WA and never needed my AC. Las Vegas temps can well exceed 115* in the summer months and much of the driving is stop and go. My temp guage will read just below max in heavy traffic. During the cool months the temperature is normal. Thanks for your response.

 

SJW, thanks. I sent TJWong e-mail.
Roger
Las Vegas

 

I live in AZ so I can relate to the high temp issue. I did this to my LT4 and it runs ALOT cooler now. Also went w/ 90% distilled water/10% Dexcool and added 2 bottles of Water Wetter. The difference is night & day...car never goes over 208-210* (even in stop n' go w/ a/c on) in the baking summer heat. Before doing this, I was seeing 235-240+ temps under the same circumstances.

FWIW..Also just installed a EWP last weekend, so I expect my stop n' go temps should drop even a bit more.

One more thing, let the digital gauge be your guide (not the analog)...as it gives a more accurate reading of the coolant temp.

 

JEFNLSA, thanks. I never considered your suggestion. I'll give it a try. I did change my thermostat to 160* although I know it won't affect my operatering temps.

 

I was waiting for someone to comment.

 

Bad info? Most of the post on this board are subective my friend. If you bother to read the question the gentleman is running in the dessert. Simply resetting the temp progs will not do the trick imo. Having spent time in Vegas driving an LT1 with a 160 stat the cars temp never exceeded 195ish. Granted she ran a little rich but overheating was not an issue.

Your entitled to your opinion as well .......

 

http://gmtips.com/3rd-degree/dox/tips/cool/cool.htm

 

I installed this kit on my 95 and wow what a difference I had to remove a plug from the side of the block put in the sensor that came with it wired into the fans and bam no more 200plus.

 

Hello,
Here in Georgia we get about 105 or so degrees in the summer.

This is what I did(I am not saying this is the best, worst or telling anybody else to do this!): I installed a 160 degree thermostat, a Fan switch to turn-on that fan at 175 and turn it off at 165, a relay to turn on the front fan with the ignition and a PROM programmed for the car to run cool without enriching the mixture, like a 'cold-choke' condition.
The car used to run up to about 235-240 in traffic or a drive-thru and that gave Me a lot of stress! It now doesn't get over 180 in the worst traffic conditions, now! I am Happy with My mods and if you(anyone) doesn't like them, than BY ALL MEANS DON'T!!!!!!!!!!!
The sensor for the fan switch is on the driver's side between cylinders #1 and 2 (NOT cylinders #7 and 8), on My 87 model. I run about 30% anti-freeze/coolant and 70% water, I too add two bottles of water-wetter(one bottle doesn't seem to do much but two bottles work good).
This info is for your information and is not an argument.
Take Care and Be Safe, -John

 

The OP has an LT1 with the reverse cooling system. Therefore, the info in this post doesn't apply.

If you knew more about engines, you wouldn't be quite so pleased with your "mods".

RACE ON!!!

 

I was waiting for this post. Was not disappointed.

 

Are you getting any more advance out of the "coolant temp vs advance" table?

On my buddies iron headed L98 a thermostat change, fan temp enable change, a little bit of fuel reduction, and a hair more advance got 1/2 second reduction in et.

-- Joe

 

I'm also in Hot Arizona. IMHO, the 160 t-stat is a waste of money. Within 2 blocks, you're temp is going to be 180 anyway, so it really accomplishes nothing. What helped me the most was installing a big-azz Ron Davis radiator with the primary fan coming on at 195. No overheating problems anymore.

 

i was just about to say that