I have just recently purchased a 95 Firebird with the lt1. it has 60,000 miles on it and runs great, or so i thought. As I was in town last saturday sitting in holiday traffic the temp gauge moved up to over 230 almost 240 before the fan kicked on. I came home and installed a new temp switch, relay, thermostat and flushed the system(which was in need of new coolant anyways). And the cooling fans still will not come on till almost red line. I can turn the ac on and the temp drops to 185. I know that the fan runs because it comes on with the air conditioner. Is this a common problem or do i have a wiring nightmare on my hands? And would it be worth it to install a adjustable electric fan wiring kit from jegs so I can just set the temp myself, prob the radiator and be done with it?

 

So, the gage works but the PCM doesn't seem to know how hot your engine is getting. There are 2 temp sensors. The one in the head runs the gage in the IP, but the PCM reads the one in the water pump. Sounds like the PCM is not getting a good temp signal, but the gage is. I'm guessing you changed only the sensor in the head? Check the one in the pump. Electrically all else sounds OK since you get fans with A/C.

 

best thing to do is to get the PCM scanned to see what kind of temp readings the PCM is seeing. it could be a bad temp sensor... but it's better to pin point the problem before throwing parts at it and hoping it gets fixed.
if it is the temp sensor just know that the two (one in the head and one in the w/p) have two different part numbers. i don't trust anyone to get it right except the dealer. been through that twice with different parts stores where they gave me the wrong one. shoebox should have the part numbers on his page:
www.shbox.com
just went on there to see if it's there and of course it is...
part number is: 15326386

 

The stock fan settings turn the fans on low speed at 225*F and high speed at 236*F. When you turn on the A/C it turns the fans on at low speed, no matter what the temperature is. As noted above, check the water pump sensor performance, either by observing the temperature fed to the PCM, using a scanner, or by measuring the resistance of the sensor at various temperatures.

 

Another possibility is that the gauge is reading high (and everything else is working normally). Again, using a scanner, you can compare the reading the PCM is getting to what the gauge is saying.

 

I replace the on in the water pump.... Has the temp sensor for the gauge been known to go bad? Because supposidly the man at napa said there was a bulletin for the on in the bottom of the water pump going bad. So if figured for 10 bucks it was worth a shot.

 

the stock fans are set to come on that late? isnt that a little to warm? Im used to shutting a normal (70s and 80s model) 350 down at 220. and wont that kill the performance

oh and thanks for the part number i'll cross it with what i put in to make sure they got it right

 

You need to update to the current EFI tech, reflecting the demands of fuel economy and emissions. GM designed the engine to run at 200+*F. That gave them good fuel economy and minimum emissions.

Higher coolant temperatures can increase the thermal efficiency of the engine, increasing both power and economy. Where you get into trouble is where the increased coolant temp can transfer heat to the incoming air charge, as in the coolant heated throttle body. Remove the coolant and you net 6HP. And, running a 160*F t'stat, and lowering the fan on/off temps will also increase power, apparently because the elimination of air charge heating, and the ability to throw in a couple degrees more ignition advance more than offset the loss in thermal efficiency.

Look at the tech info on Evans NPG coolant. By running the engine at a hotter coolant temp, and using a coolant that addresses nucleate boiling, it allows the production of more power. Evans has the patent on the "reverse flow" coolant system used in the LT1 engine, and successfully sued GM to prevent them from using it..... hence the return to "conventional" flow cooling in the LSx family of engines.

http://www.evanscooling.com/index2.html

 

Is it safe on the fan motors to run both fans 100% speed all the time? I live in FL and my car is always hot so it might be a good idea to have a manual fan switch?

Sorry for the Hijack!

 

Safe for them to run all the time? Probably. A waste for them to run all the time? Yes, IMHO. A 160° thermostat and some fan reprogramming would likely solve any cooling issues you might have.