I have a 2005 Mack granite CV 713 dump truck with an Allison 4500 RDS transmission. The truck's coolant temperature maintains a minimum of 175° throughout the day. The air over electric fan engages at 205° as it should. The Allison was typically running at a temperature of 10 to 15° higher than coolant temperature. Over the last 3 days the Allison has not exceeded 160° (typically 150) under load and quickly drops to 120° upon any short length of time idling. Both thermostats and coolant temp sensor on rear of manifold are less than 3 months old (plus truck coolant maintains operating temp, as prior to thermostats it was running 150). Replaced the transmission temp sensor yesterday and transmission dash gauge continues to run cold. Any thoughts or suggestions? TIA.
