I have a 2010 E450 28ft Forest river with the V10 5R110w transmission with 49k miles. Over the weekend I was pulling my 20ft enclosed trailer with 2 quads and a Side by Side in it. Pulling a long hill going 45 in second gear it started smoking from underneath the RV. I pulled over turned it off and crawled under. trans fluid everywhere but could not find a leak. started it back up and still no leak. checked fluid level and it was about a quart low didn't smell or looked burnt so I continued on to the next stop. topped off the fluid and continued on. went up 2 passes in Idaho (lookout pass and 4th of july pass) without an issue. Went up Vantage hill in central WA that is a 10 mile hill 2nd gear 45mph and 90degrees outside all fine no problems. stopped and fueled up and the next hill it started smoking again so I backed off the throttle and slowed down to 35 mph and the smoke went away. Slowly made it home without further issues. It looks like the fluid was coming out the breather on the top of the transmission.

What would cause this? how can I prevent it from happening again?

 

How many miles on present trans?

When was it last serviced and by whom?

Was anything done to the trans cooler?

I have seen where the trans fluid was low, and it started to aerate and come out the vent.. This all happened pulling a hill.

There may be a reason the level was low and operator was not aware of condition..

 

52k miles. I have no record of any service done to trans. I have owned it for 5 years and have put about 20k on it. Nothing done to trans cooler as far as I can tell. Seems small for a coach.I checked the level before the trip and it was good. Ran great from Seattle to yellowstone to Rexburg ID. to about half way to Butte Mt. before it happened. Was sluggish at the time but i figured it was part altitude and part headwind and hills.

Also there is some surface rust on the top of the dipstick?? but the fluid is not milky or discolored at all. Does not look dirty or burnt at all. Just condensation?

 

Pretty sure if unit is used to tow trailer, trans service is due around 30,000 mi.
Might be a good idea to verify with what owner's manual recommends..

 

I am going to change filter and replace the cooler and add a second cooler to the system.