What trans temp does your truck normally run unloaded in cold weather (below 20 degrees F) ? Mine seems to stabilize around 40 degrees. That is much lower than any other truck I have had. Other truck I have owned will stabilize around 85 degrees in cold weather. Is my 40 degrees ok, or is there a thermostat for the trans somewhere that may be stuck open?

 

At approx. 25 F my trans oil will reach 155 F

 

My trans in the winter, temps single digits to twentys, will be around the upper 140's to lower 150's.

 

i was having that same question. around here (southern mn) its been pretty damn cold. mine wont go over 120-130 when it would usually run 150ish. i have not yet figured it out..

 

Where are you measuring the temperature? That is too low. There is a thermostat in the trans, it could be stuck open.

 

Depends on how fast and how far I drive but mine operates around 150-160F once it gets warmed up good.

 

Isn't the transmission fluid cooled by engine coolant?

 

I believe all SD's came with a separate transmission cooler. It's not tied into your radiator.

Towing and 8500lbs skidsteer and 2000 lbs. trailer, mine recently hit 164 at -25C. I think your temps really depend on how cold it is, how long you drive and what kind of load. The 40 degrees though would have me worried. That is way too low. After a few minutes (5-10) of idling at -25C, my tranny temp will be over 60F.

 

I noticed the same thing - hoping this is normal. My temp was at 40F at around 20F with no load and hwy driving. Heated a little bit when I got into stop and go traffic.

 

Update: I put a "winter front" on the truck from a 2010 super duty and it fit right up. Ambient temp on the way to work was 3 degrees F. Trans temp stabilized at 60 degrees F 20 degrees higher than what I've been seeing. I'm almost positive the thermostat is stuck open now. I've heard its a pita to change though. Anyone see a problem with putting an "inline" thermostat after the external trans filter?

 

Yes it is, but the TorqShift has a thermostat. When the trans is under 165°F the flow to the coolers is cut by 90%.

All SDs from mid-2000 to present came with a separate trans cooler AND a trans cooler in the radiator.

You're probably right. The thermostat is located in the pump body. The trans has to come out of the truck to replace it.

I don't know anyone that has tried and external thermostat.

 

Better replace the factory one.

 

Not to insult you but are you sure your not reading celsius? 60c = 140f

 

I talked to the mechanic at my dealership today about the above issue, after an hour of talking and looking at one that he had in pieces he suggested a hot flush before we went any further to see if any gunk had accumliated on the thermostat.

I have also thought about adding an external thermostat to cure the problem, and today I found out that the 4r100 had one. I don't know if this would work or not, but the mechanic told me ford pays 6.5 hrs. to remove and install the trans, that doesn't include tear-down to replace thermostat.

 

The 4R100 did not have any thermostat inside or outside the transmission. It did have a pressure bypass, but it was not a thermostat.