This morning I noticed how much these things hold their heat. The trans, oil, and coolant were all about 60ish degrees after sitting in 30ish degree weather for a little over 7 hours.

 

Yep, with 3 gallons of oil, 16 gallons of coolant, and approx 400lbs of iron that's an awful lot of mass that holds heat. Think of the side of a brick building at night that gets direct sun all day, it feels warm to the touch throughout the night.

The opposite is true as well, when the engine and fluids are below 30° to start with it takes a good 30 minutes to get things warmed up, maybe longer if you're driving slowly.

 

Team,


An update from an entertaining day with the dealer. No disrespect to Ford, but their troubleshooting guide and shop manuals never considered the failure mode of an overcooling transmission, just overheating.


I got the usual responses to my questions which clearly showed the tech really did not know how the system was supposed to work. The troubleshooting guide he showed me had tests for transmission fluid flow through the transmission cooler at three set points - 160Deg, 170Deg, and +180Deg. Interesting the flow values doubled at each increment (16, 32, and 64 oz per 15 sec). I told the tech that this indicated that there was some form of thermostat or solenoid that controlled flow to the cooler as a function of fluid temp. This of course contradicted his assertion that fluid always flowed to cooler.


I finally had a chance with the service manager to look through all the ford documentation and troubleshooting material and neither of us could find anything that tells the tech what the fluid flow through the cooler should be at lower temps (warm-up for example) nor what the target operating temp should be at steady state. Beyond that, we could not figure out whether the flow ways controlled by a manual thermostat or an electronic one, though there was a note that there is an electrical control on the front transmission pump that would seem to control flow, but it is not a signal that he could see using the Ford diagnostic software through the ODB port.


They were nice enough and we did go ahead and change out the fluid and transmission filter, but I am no closer to figuring out if there is a problem or what its root cause might be.


On the plus side since they had the truck already fully warmed up before I headed home for the day, I was able to confirm that the set point for the transmission is around 195F which is what most of you have indicated that you see. In 50 miles I have not been able to get above 170 on a 70F day so there is clearly something going on. Additionally, my MPG returned to its previous level over the same 50 mile drive I make every day. I think the overcooling is impacting my MPG, which is what I have been chasing all along.


At this point, its now a science project - what is going on, how does the system really work, what component is not working, and at the end of the day, what the heck am I going to do about it.


Fun times, but I really wish I had a Ford cooling system engineer to chat with - engineer to engineer.


Stay tuned and thanks for everyone's help and support.