Transmission temp.

240/250 for short periods of time will not hurt it . just use a good fluid. I added another trucool cooler to my F350 because I tow a 12K toyhauler on long 6/7% grades in Az heat. Rarely gets above 180 unless in stop & go encountering an accident or something. You are fine. Change the fluid regularly with good fluid and put some tape over the gauge.

That's why manufacturers don't like gauges. Too many nervous customers. The preference is either warning lights or gauges which read "normal" until it isn't.

Trannies usually can take temperature "peaks" beyond normal operating parameters as long as they don't last too long and the oil is maintained.

Long ago, I made the mistake of putting a SW tranny heat gauge on my old '84 Itasca 454, probably one of the hottest running RV ever. And every year after that.....while towing my 19ft boat. I saw 300 on the gauge while climbing Donner Pass to L Tahoe. (I-80) I changed fluid every couple yrs as I remember, but it never smelled burnt. Last I knew, that tranny is still going. Trannys work better w/o heat gauges.
Yep, like I was going to stop 1/2 way up Donner and let it cool off !

The temps sound normal to me. I can see tranny temps in the 220-230F range while towing in the hills. Been that way for 18 years now with the same tranny. I do keep the fluid fresh.

Normal. Service by the book.

My fan clutch was kicking in as well as the electric cooling fan. It has a factory external cooler on it and like I said it was running cool enough on the level at interstate speeds but it went high when pulling a grade after a lot of stop and go traffic with some pretty good grades and then went to 215 on a real steep climb.
the fluid is still nice and red. I asked my GM mechanic and he didn't seem too concerned considering the situation. I think I am OK on flat ground but not sure I would feel comfortable in the mountains with the Jeep towed behind. Thanks for all comments!

According to Allison normal operating sump temperature is 160°-200°F.

The best thing you can do is change the trans fluid to synthetic trans fluid and then you won't have to worry about the trans temps.

I routinely hit 210 on steep grades. Right around then the clutched engine fan kicks in and starts bringing it down a little (ATF cooler is integrated into the radiator). The tranny temp usually tracks the engine coolant temp pretty closely.

190 is no problem. You really don't want to drive the motorhome to often when the temperature is not above 165 before shutting it off. This can cause condensation within the transmission oil to collect water vapor, while going above 180F will boil out all that moisture.

215F is also not a problem if it is temporary. 215 for a long distance, or while on a flat area indicates the need for a larger transmission cooler. . If it reaches 230F, you can slow down, and this should reduce the transmission temperature right away. 250 can be damaging to the transmission, so if it goes that high, pull over and rev the engine enough that it starts to cool down (don't shut it off, that stops the cooling process). 300 and I hear that the transmission fluid is good for about 500 miles. 275 and it is good for all of 1,000 miles. 260 is good for around 3,500 miles. 250 - 5,000 miles. 215 and you still should change the fluid every 15,000 miles, to that it stays fresh, and looks red. If it turns brown, then change it right away!

If you just bought the RV, it is a good idea to flush out the fluid, and change the rear axle fluid as well. Brake fluid is only good for about 7 years, some change it at 6 years old.

If you drive the rv up a steep mountain grade, and do not hear the fan clutch engage, it is probably bad, and needs replacement. That will bring down the coolant and transmission temperature fairly quickly. If you are running 215 F transmission fluid, then the clutch probably engages, then gets really noisy, and pulls about twice as much air through the radiator, providing a lot of cooling.

Have fun camping!

Fred.