Transmission temperature question

[lancekeys]

I have never towed anything with an automatic, but I know the temperature is critical. I will be towing with a 2009 Tahoe next weekend. At what temperature should I be concerned? Other than keeping it in T/H mode, is there anything I can do to make the transmission work better while towing?

[fly-boy]

Tystevens wrote:

fly-boy wrote:
If I pulled over every time my transmission reached 200 I would never get anywhere.

Yeah, my F150's transmission apparently has a thermostat, because it gets up to around 195* in a hurry (20-30 min of driving) and stays there, even unloaded and in cold weather.

Yup- my current truck is by far the best I have owned at staying cool under stress- it just does not get near as hot as other I have owned. That said, I added a bug screen to this one when I first bought it and I think it has really helped keep the radiator fins a lot cleaner.

Got the trans up to 254 on my 2008 one time. Changed the fluid when I got home and asked the dealer about it- they said not a big deal. Traded that truck in with 100k on her and she ran as strong when I let her go as when I bought her.

[Tystevens]

fly-boy wrote:
If I pulled over every time my transmission reached 200 I would never get anywhere.

Yeah, my F150's transmission apparently has a thermostat, because it gets up to around 195* in a hurry (20-30 min of driving) and stays there, even unloaded and in cold weather.

[BurbMan]

The chart is outdated due to the temps that newer synthetic fluid can safely handle.

[fly-boy]

If I pulled over every time my transmission reached 200 I would never get anywhere. My trans typically runs 85-90 degrees above ambient air temperature- unloaded- but running fairly fast.

With a load on hot days trans temps often get into the 225-230 range- which is no big deal. The allison can run at that temp all day long.

On a lighter duty trans, I would do my best to keep temps under 220- They hold less fluid and generally have much smaller coolers so it can get too hot fast.

When in doubt, travel at night or plan your grades for early morning. Have pulled the Baker grade when the big thermometer read 126 and when its read 60- ambient air temp makes a giant difference!

[BurbMan]

Tystevens wrote:
Wow, 2 days worth of posts and no one has posted that stupid old transmission temp chart?! I'm impressed!

Per your request:

[APT]

Tow haul mode. If 4-spd, lock out overdrive. If 6-spd, I recommend M4 or M5.

[Tystevens]

Wow, 2 days worth of posts and no one has posted that stupid old transmission temp chart?! I'm impressed!

With an '09, you have a 6 spd, correct? Our '10 has gotten as high as about 235* a few times with no apparent adverse effects. Usually it is right around 200* when towing; going up steeper interstate grades it will inch higher up around 215*. 235* was towing up a very steep and long 2-lane which climbed from 4000 to 8000 ft elevation over about 8 miles, so that was a workout.

I generally monitor temps most of the time I'm towing, but I wouldn't be concerned unless or until a "too hot" message popped up on the display.

Good luck!

[Old-Biscuit]

BurbMan wrote:

Vannnce wrote:
Dont be afraid to pull over. the temp drops quickly when you stop.

NOTE that when/if you pull over, you should leave the engine running to keep the fluid circulating through the cooler.

And depending on tranny....may have to leave in Neutral for pump to circulate. Not all do when in Park

[BurbMan]

Vannnce wrote:
Dont be afraid to pull over. the temp drops quickly when you stop.

NOTE that when/if you pull over, you should leave the engine running to keep the fluid circulating through the cooler.

[Vannnce]

I have both gauges in my truck, and the torque app. My tranny temp varies based on ambient air temp. I have my torque app set to beep at me at 215. at 220 i pull over to pee, stretch the legs and so on. Dont be afraid to pull over. the temp drops quickly when you stop. Some may run hotter, i prefer not to and i rarely ever see that hot

[ktosv]

What size/weight trailer will you be towing? With a 2009 I believe that you still have the four speed transmission. Depending on the size of the trailer, I think I would keep it in thrid/drive and use tow haul. When using tow haul if the trailer is large enough, it probably wouldn't want to shift into OD anyway...at least with my 05 Suburban it wouldn't until up around 65MPH with tow haul on in OD.

[poncho62]

I have a trans cooler and temp gauge...I tend to worry a bit more when it hits 200f. It doesnt seem to stay there long, usually in the 160-180 range

[intheburbs]

Dexron VI begins to break down at 270°. I doubt you'll get anywhere near that.

I recently pulled my TT on I-70 in CO over Vail Pass and the Eisenhower tunnel. Total weight was 14,500 lbs. We were also doing some four-wheeling in Moab in 100°+ temperatures. Through all of that abuse, highest my trans temp went was 235°.

Keep an eye on it if you want, but the computer will put the truck into limp mode or tell you to pull over and idle the engine if things get too hot.

Have fun.

[lancekeys]

No gauge, but the area where the odometer is can be set to read trans temp. We have a small trailer, so should be no problem, just wanted to know.