Absolutely. Many automatic transmissions rely on the engine's cooling system to help regulate transmission fluid temperature. It's possible for the engine to maintain a normal operating temperature while the transmission is running much hotter than it should.
Here are some of the most common causes:
Restricted Transmission Cooler
The transmission cooler or cooler lines can become partially restricted, reducing the amount of heat the fluid can shed. The transmission may shift normally when it's cool, but as temperatures rise in stop-and-go traffic, the fluid gets hotter and shift quality begins to change.
Cooling Fans Not Operating Properly
When you're moving down the highway, airflow through the radiator and transmission cooler keeps temperatures under control. In traffic, the cooling fans become the primary source of airflow. If a fan isn't operating correctly or isn't reaching high speed when needed, transmission temperatures can climb rapidly—even though the engine temperature gauge remains in its normal range.
Torque Converter Clutch Problems
If the torque converter clutch isn't applying properly, the converter continues to slip and generate heat. The extra heat often becomes most noticeable in slow traffic, where airflow is already limited.
Valve Body or Hydraulic Problems
As transmission fluid gets hotter, internal hydraulic leaks or worn valve body components may become more noticeable. The result can be increasingly firm or erratic shifts as operating temperature rises.
Engine Cooling System Issues
A radiator that's partially restricted internally can still keep the engine at a normal temperature while reducing its ability to cool the transmission fluid that passes through the transmission cooler built into the radiator.