Update: the ACDelco fan (Actually Behr part) works great, no roaring, very quite.
New problem, coolant temperature lower (188-192 F), it used to be 196-198F (using OBD). The more the Engine is revved, the lower the coolant temperature gets (towards 188).
like this thread
- Thermostat: ACDelco - replaced 2 years ago (20k miles ago)
- Temp sensor: I never replaced it. IDK about previous owner
- Coolant: Dex cool 50/50. <1 year old. In changing the fan, drained and reused 2 times. There were some particulates in it but I filtered it through coffee paper.
Not sure if particles got in and thermostat is stuck open? Sensor is bad? or system not burped properly. Truck seems to warm up as fast as before.