Thermostat and fan1&2 switch on temp

[69chevpu]

I am putting a '04 5.3L into my 67. No A/C currently but will add later.
I am getting ready to have my pcm programmed and I am putting a fresh thermostat into the engine.

Questions are:
1. What temp thermostat should I get? What is stock?
2. What temps should I have the pcm programmed to for turning on Fan1 and then Fan2?

Thanks, Mel

[Clyde65]

stock for LSx engines is 195 degrees I think.

Summit has 180 degree thermo stats for LSx engine but remember the LSX engines are designed to run at the higher temps.

With mine, I kept freaking out everytime mine got over 180 degrees for the first month. Now I dont get worked up until it gets over 210 or so. It only gets there when I am in traffic and have the AC on, yes I have dual electric fans and an aluminum radiator but it does get warm. I dont know what the PCm thinks the temp is, I am going from an Autometer guage. Also you can adj the fans on/off temps in your PCM tune if you want.

[TR65]

Clyde,

My 2005 LS2 6L runs a 190 thermostat as stock. I have talked to a couple of "experts" and they say these engines need to run 190. (Actual is 191-193 according to the ECM)

The stock program turned on the first fan at 220 and back off at 210.

I backed that off to 210 on, 200 off.

Basically my fan never comes on unless I am sitting at idle for 5 min or so even in the hotest SC day. Never had the second one come on.

I suppose that they will run a lot more with the AC I am installing now. The ECM uses AC system pressure to control the fans when the AC is on.

TR

[Clyde65]

TR65, I have also heard that too, that the LS' run hotter than the SBC's, I just couldnt remember what temp, I have a stock 02 truck harness ( engine is actually a 05 with DBC TB on it) that doesnt have the fan control wired, it might do it, I just dont have it wired and dont know how.

[TR65]

Clyde,

I think the trick it to obtain the factory service manual that goes with the computer and harness (if stock) that you have. Then you can find the wires that control the fan relays and you are off to the races. At least that is the way I did it.

TR

[cableguy0]

Most modern engines are running at north of 200 degrees. It helps to have a more complete burn and keeps the engines cleaner inside. Thats why temp gauges dont have numbers on them factory anymore.