Running Hot - Need Advise

[jblowers]

I took delivery on my first Corvette last week - a 1996 Collector Edition and of course I couldn't be more pleased. I'm working what I think might be an overheating problem and could use some advise.

I am basing my comments here on the stock temp. guage in the dash - the guage has a 185 & a 260 degree marker indicator with two equally space tick marks in between. I'm assuming each one to be 25 degrees so I'm assuming 185, 210, 235, 260 on the guage.

The day time temps. in Dallas have been about 90 degrees as a reference.

On Saturday night while driving to the IRL race - country road, no AC, driving between 65 - 75 MPH the temp. seemed to reach around 250. Leaving the race, in idling traffic to get away from the track it almost pegged the needle. Sunday I looked things over and found what appeared to be a bird nest pressed into the radiator cooling vanes. The same for the AC cooling unit (the radiator looking thing in front of the main radiator). I cleaned all of that off with my shop vac and a brush.

Today while driving to work without AC it went to above 235, coming home in 90 degree temperature, and AC ON is also got close to 235. There does not seem to be any overboiling into the overflow tank.

Coolant level seems fine with plenty in overflow tank. Fans come on with AC turned on. Fans also come on once the guage reads somewhere around the 235 degree mark. I've read in a service manual that the primary fan should come on at around 219, second at around 230 or so.

I could sure use some advice on this. Thanks in advance.

 

[Edmond]

How about a system flush? Since you've cleaned out the bird nest, that should be fine.

I haven't done this, but it's said here that if you add Water Wetter, it will reduce the temp by a few degrees.

You can also reprogram the computer to turn the fans on earlier. I believe your model is tuned with LT1 edit. The earlier C4 models replace the whole chip, which is what I did and my fans turn on at 200.

 

[SPANISHVETTS]

Congratulations on the CE and welcome to

Check the temp with the digital readout in the HVAC unit. The analogue gauges are famous for inaccurate readings.

Hold down both the fan up and fan down buttons for about 10 seconds. The read out will go into diagnostic mode. Use the fan up or down button to select ¨16¨ on the readout and press the middle fan button. The readout will now give you the coolant temp in ºC, a quick conversion to ºF can be made by doubling the readout and adding 32.

With ¨bird nest¨ in your radiator you need to do a more thorough cleaning. This requires removing the radiator and cleaning it with soapy water and a soft brush. Do a search here and you will find a lot of info on the procedure. It is not really that big of a job.

Corvettes do run HOT. The folks here at CAC are of mixed opinions as to whether to cool them down or not. I over cooled mine and now suffer from terrible gas mileage on short runs however once the beast gets up to temp it stays nailed to the thermostat opening temperature. 93 in the shade here today and the Vette is hovering aroung 190 in traffic.

 

[all4c4lt4]

On the 96 your fans are set to come on at about 235. This was done by GM to help pass emissions. However, it is way too hot for you to run consistently. Besides the additional wear on the engine, you are robbed of performance. Alot of people do the following:

1. You need to pull the radiator and clean it thoroughly. Just vacuuming is not enough. (ask me how i know). Although, I would advise to replace the radiator w/ an aftermarket one if you pull it. Be Cool rads are popular, but almost anyone will be better than stock. Fit is usually the only question when replacing the rad and how much modification it takes to install it.

2. Do the throttle body bypass mod.

3. You can use water wetter, I have and it does work to some degree.

4. Reprogram your fans to come on earlier. This is essential. Mine come on at 195 and off at 188. You can send your computer out to have it done (pcmforless.com) or waste your money on a Hypertech PPIII to do it. I recommend getting a custom tune and having it done then.

5. Replace the stock thermostat w/ a 160* one. The engine will not operate at 160*, more like 170 - 175, which IMO, is perfect.

 

[vader86]

I think youve got a stuck stat or a dying WP.

Those temps shouldve dropped when you cleaned the radiator.

 

[Rabbit]

The gauge in the dash is not graduated as you wrote. The owners manual will give you the corrected version of analog.
Whats the reading on your digital?

 

[cntrhub]

Factor in ambient temperature during the day. Hold on swapping out all this radiator, fan, and all the other things I've read. Do a simple test first. Drive the car during the night. If it's cool out, even better. Early morning, before the sun comes up would be ideal. If you have a cooling problem, the needle will peg no matter what the air temperature is...day or night. Stuck stat, clogged water jackets, Condor nests you can't see, all those variables and more, will overheat an engine.
If you find the gauge is running normal driving late at night, it's just the ambient temperature adding heat to the radiator during the day. If you peg the needle up into the 230 plus range looking at the stars, then I'd start thinking about ripping things out.