2010 Mountaineer 5R55S leaking mystery

[FHP89LX]

Just wondering if anyone had a similar situation

2010 Mountaineer with 176K
Transmission rebuilt in Feb 2021
Shifts like new
This labor day weekend I was driving on highway 10 where we have lots of mountains here in Arizona. I was going uphill and I was speeding up to pass an RV. When I passed it I notice smoke coming from under the Mountaineer. I looked under and transmission fluid was all over the exhaust. After about 2 minutes it stopped leaking. It leaked very little but I did drive the truck back another 60 miles with no issues.

Going uphill I did not force the truck and I was going about 50mph on a 75mph lane. Still no smoke, no tranny leaks.
Next day no leaks, so I used my car for work. I do Doordash so I had to use the truck. It still shifts like new because my transmission was rebuilt back in February 2021 and NO Leaks indicated
I am guessing that if I take the highway again going uphill and 70MPH, it could possibly leak again. I think it could be a seal or sensor. Last week I was getting the yellow wrench but I am not getting it anymore. Any ideas would appreciate it.

 

[06MountaineerPA]

Did you check the level of the fluid? Maybe you leaked it all out and that's why you don't have a leak.

 

[imp]

Just wondering if anyone had a similar situation

2010 Mountaineer with 176K
Transmission rebuilt in Feb 2021
Shifts like new
This labor day weekend I was driving on highway 10 where we have lots of mountains here in Arizona. I was going uphill and I was speeding up to pass an RV. When I passed it I notice smoke coming from under the Mountaineer. I looked under and transmission fluid was all over the exhaust. After about 2 minutes it stopped leaking. It leaked very little but I did drive the truck back another 60 miles with no issues.

Going uphill I did not force the truck and I was going about 50mph on a 75mph lane. Still no smoke, no tranny leaks.
Next day no leaks, so I used my car for work. I do Doordash so I had to use the truck. It still shifts like new because my transmission was rebuilt back in February 2021 and NO Leaks indicated
I am guessing that if I take the highway again going uphill and 70MPH, it could possibly leak again. I think it could be a seal or sensor. Last week I was getting the yellow wrench but I am not getting it anymore. Any ideas would appreciate it.

5R55S has NO DIPSTICK or fill tube, if you do not know that. Therefore, transmission is vented otherwise to the atmosphere. A replacement rebuilt usually comes with NO VENT TUBE. The old tube must be removed from the old transmission and placed in the new transmission. Without the vent tube in place, fluid is likely to spew out under certain conditions.

WAS THE TUBE PLACED IN THE REBUILT TRANSMISSION?

"The external vent assembly must be removed from the original transmission and installed on the new, remanufactured transmission."

1. Remove the vent assembly from the original transmission.
   1. Use caution when removing the front, middle, and rear fittings from the transmission. Note: some models only have the front and rear fittings.
   2. The front is easily removed by gently squeezing the inner tabs slightly. You can see these by looking in at the top of the bell housing. These tabs are designed to lock in place, so do not attempt to remove the fitting without squeezing the tabs. (Fig. 1)
   3. The middle fitting, if present, is simply a tapered, press fit. Using a pair of locking pliers, twist the fitting back and forth as you pull it out.
   4. The rear fitting has tabs, but is not a locking design. (Fig. 2) Pull it out by hand, being careful not to bend it to the side. A twisting motion will help to ease the removal process.
2. Install the tube assembly in the remanufactured transmission in the reverse order.
   1. Insert the rear fitting in to the case. If necessary, lubricate the fitting with a small amount of clean transmission fluid.
   2. Gently tap the middle fitting down to secure in the case. A small amount of thread locker can be used if necessary.
   3. Insert the front fitting into the bell area.
3. If a replacement assembly is needed, then you can use the following part numbers to help getting the correct assembly from the dealer.
   1. For 5R55S and 5R55W units: OEM# 6L2Z-7034-CA
   2. For 5R55N units: OEM# 4W4Z-7034-AB