57 chevy truck swap, cooling issues
07-07-2022, 10:49 PM
#1
57 chevy truck swap, cooling issues Donor engine is 2004 avalanche, 5.3 flex fuel. I bought it from someone else that had the ECM unlocked by lt1swap.com, over 10 years ago, so I have no idea what has been done to the ECM. I installed it into 57 chevy truck with LS swap aluminum radiator (steam port), 2 speed electric fan.
Fan issue. I have no idea if or what temp the ECM is programmed to run the fans. At approximately 205 degrees, the low fan (fan 1) triggers ON. Shortly thereafter, it cycles the low fan like a turn signal "on/off" which then overheats the relay. The temp keeps climbing until I shut it down at around 220-225 degrees and let it cool down. I have never run it long enough to see if the temp will get high enough to trigger the HI fan (fan 2).
Questions... Since the donor did not have electric fans (mechanical fan), would it need the fans to be manually programmed into the ECM? A family friend (retired mechanic) thinks it is a bad "driver" in the ECM, not programming.
How hot can I safely run it to see if fan 2 will trigger ON?
What is an optimum temperature to run this engine? I have seen numbers all over the internet from ranging from 190 - 220.
Next, when the temp is showing 220, I checked the radiator with an infrared thermometer. The top of the radiator is about 220 and the bottom is about 130. Do aluminum radiators really cool that much top to bottom, or would that mean the thermostat is stuck? How could I verify if the thermostat is opening properly? I put in a new 187 thermostat before installing the engine.
Thanks!
Fan issue. I have no idea if or what temp the ECM is programmed to run the fans. At approximately 205 degrees, the low fan (fan 1) triggers ON. Shortly thereafter, it cycles the low fan like a turn signal "on/off" which then overheats the relay. The temp keeps climbing until I shut it down at around 220-225 degrees and let it cool down. I have never run it long enough to see if the temp will get high enough to trigger the HI fan (fan 2).
Questions... Since the donor did not have electric fans (mechanical fan), would it need the fans to be manually programmed into the ECM? A family friend (retired mechanic) thinks it is a bad "driver" in the ECM, not programming.
How hot can I safely run it to see if fan 2 will trigger ON?
What is an optimum temperature to run this engine? I have seen numbers all over the internet from ranging from 190 - 220.
Next, when the temp is showing 220, I checked the radiator with an infrared thermometer. The top of the radiator is about 220 and the bottom is about 130. Do aluminum radiators really cool that much top to bottom, or would that mean the thermostat is stuck? How could I verify if the thermostat is opening properly? I put in a new 187 thermostat before installing the engine.
Thanks!
07-08-2022, 12:27 AM
#2
TECH Senior Member
Which fans are you using? Twin fans are not usually 2 speed.
The following users liked this post:
G Atsma (07-08-2022)
07-08-2022, 10:28 AM
#4
One Volvo 2 speed fan. Fan1 = LO, Fan2 = HI. Not a fan or relay issue. It is computer issue. The ECM is pulsing the fan "on" signal, instead of continuous on.
After filling and running a couple times, I jacked up the front end, pushed the upper hose below the filler and topped off the coolant. I'm sure it is properly burped and the block is full of coolant.
What is the best bang for buck way to get into the ECM and re-program the fans?
After filling and running a couple times, I jacked up the front end, pushed the upper hose below the filler and topped off the coolant. I'm sure it is properly burped and the block is full of coolant.
What is the best bang for buck way to get into the ECM and re-program the fans?
The following users liked this post:
G Atsma (07-08-2022)