macmac
Well-known member
This is a question about my truck's cooling systems ?
I have a Silverado, 1 ton dually, Duramax/Allison powertrain, new in 2004, standard specification for towing. It hauls a 13,000lbs fifth wheel.
When it?s working hard on tow I hear various fan noises. These increase in intensity and speed as the engine gets hot but I?ve never been able to figure what fan is making what noise. I can see a large diameter, viscous-coupled fan behind the two closely mounted large radiators and that?s all. I can hear that kick in and out, speed varying according to the gear I?m in.
So what other fans (if any) can I hear and what causes their speed to increase markedly under heavy load sometimes ? the turbo intercooler?
Lastly, towing up Wolf Creek Pass, CO, on a recent hot day I found the limit of the cooling sytem. Close to the summit I could see the engine coolant temperature was getting close to the gauge red sector. Literally as I pulled off the highway to allow the engine to cool, the engine management system indicated a coolant overheat warning. A few minutes parked in ?P? with the engine at around 1500rpm cooled the system to near normal but the transmission temperature indication didn?t budge.
Luckily I was only a half mile from the summit and as we descended the transmission quickly cooled too.
But why didn?t the main fan cool that along with the engine coolant?
I have a Silverado, 1 ton dually, Duramax/Allison powertrain, new in 2004, standard specification for towing. It hauls a 13,000lbs fifth wheel.
When it?s working hard on tow I hear various fan noises. These increase in intensity and speed as the engine gets hot but I?ve never been able to figure what fan is making what noise. I can see a large diameter, viscous-coupled fan behind the two closely mounted large radiators and that?s all. I can hear that kick in and out, speed varying according to the gear I?m in.
So what other fans (if any) can I hear and what causes their speed to increase markedly under heavy load sometimes ? the turbo intercooler?
Lastly, towing up Wolf Creek Pass, CO, on a recent hot day I found the limit of the cooling sytem. Close to the summit I could see the engine coolant temperature was getting close to the gauge red sector. Literally as I pulled off the highway to allow the engine to cool, the engine management system indicated a coolant overheat warning. A few minutes parked in ?P? with the engine at around 1500rpm cooled the system to near normal but the transmission temperature indication didn?t budge.
Luckily I was only a half mile from the summit and as we descended the transmission quickly cooled too.
But why didn?t the main fan cool that along with the engine coolant?