Tranny towing temps

[Pitch1]

What is to high? I have a 13 express 5.7. Sticker claimed "heavy Duty Transmission cooling"
I tow a 6000# travel trailer tranny temps seem to average 170/180 on the road. On one steep slow speed climb I once hit a bit above 200.
Should I install an auxillary cooler,do I already have one(Heavy Duty) or is it just not necessary?

 

[smurfs_of_war]

What is to high? I have a 13 express 5.7. Sticker claimed "heavy Duty Transmission cooling"
I tow a 6000# travel trailer tranny temps seem to average 170/180 on the road. On one steep slow speed climb I once hit a bit above 200.
Should I install an auxillary cooler,do I already have one(Heavy Duty) or is it just not necessary?

6 or 8? I think 190 is normal for the 8, so I assume a 6 speed?

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[Pitch1]

6 speed 3.55 rear

 

[smurfs_of_war]

6 speed 3.55 rear

Do you use the tow/haul mode?

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[NYCruiser]

I have the 645RFE (6-speed) tranny in my '14 also (and 3.55 gears too). I read in a shop manual at the dealership that normal operating temp range for that tranny is considered 80-240 degrees fahrenheit. Sounds like you're good. If you're gonna tow, wait until it warms up past 80 tho.

 

[NYCruiser]

Found this on google from a 2010 manual. The 545 and 645 are essentially the same trannies:

545RFE Transmission Operation
The Transmission Control Module (TCM) is programmed to allow a select variety of shift schedules that are dependent on the following physical conditions:
· Selected gear range
· Throttle position
· Engine load
· Transmission fluid temperature
· TCM software level
The TCM will adjust the shift schedule of the transmission as environmental and driving conditions change.
-16°F and below and with the transmission in the Drive position, the shift sequence will be 1st to 3rd until the ATF temperature reaches -12°F. When placing the gear selector in either 1st or 2nd gear the transmission will be on 2nd gear only. There will be no torque converter lock up and switching off Overdrive will have no effect.
-12°F and -10°F the transmission shift sequences are as follows:
· No torque converter lock up
· No shift in to 5th gear
· Delayed 2-3 upshifts
· Delayed 3-4 upshifts
· High speed 4-2, 3-2, or 2-1 kickdown shifts are prevented
· High throttle opening shifts will be early
· Switching off Overdrive will prevent shifts into 4th gear
-10°F and 36°F the transmission shift sequences are the same as above, except that 2-3 upshifts are not delayed. Switching off Overdrive will prevent shifts into 4th gear
40°F and 80°F All shift sequences are normal except there will be no torque converter lockup. Switching off Overdrive will prevent shifts into 5th gear.
80°F and 240°F This is normal operating fluid temperature. The 545RFE will be in the normal shift sequence, including allowing torque converter lockup.
240°F ATF or the engine coolant 244° F, the transmission shift sequences will be as follows:
· delayed 2-3 upshift
· delayed 3-4 upshift
· 3rd gear FEMCC from 30-40 MPH
· 3rd gear PEMCC above 35 MPH
· Above 25 MPH the torque converter will not unlock unless the throttle is closed or if a wide open throttle, 2nd gear PEMCC to 1 kickdown is made.

 

[Pitch1]

OK thank you much for that. I am more comfortable now

 

[smiley]

Do these trucks have a way of shutting down if it were to get too hot?

 

[NYCruiser]

I think they go into "limp" mode and lock into 4th gear if the tranny overheats. Did you mean the engine temp?

 

[smiley]

No I meant transmission as I was thinking they must have some way of preventing failure due to heat.


$miley

 

[smykowski]

outside air temp + 80ish degrees = my trans temp. Weird, but it's been consistently accurate since November.