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Ford F250 diesel automatic transmission momentarily sprays ATF

My neighbor and I each have a Ford F250 PowerStroke with automatic transmission, and we had a strange thing happen with his the other day. He had a 3500 lb trailer loaded with bark attached and I was backing it up his driveway. The driveway is pretty long (300-500 feet), curvey with a dog-leg, and up-grade, and the trailer has electric brakes that weren’t connected. It all seemed OK at first, but then it gradually started to resist the attempts to continue backing. The further I backed, the more throttle I had to apply. I had to shift once to go forward to handle the dog-leg and there was no resistance going forward (actually, I just costed forward). After getting lined up after the dog-leg, the resistance to backward motion continued to increase. After getting the trailer positioned where he wanted it, we noticed that the transmission had been spraying ATF during the last part of the backing.

The next morning he drove the truck without any signs of trouble, no unusual resistance and no spraying of ATF.

1). What might have been happening that caused the increased resistance and the spraying?

2). What corrective action could I have taken when I noticed the increased resistance?

3). Might his tranny have suffered damage?

4). Is this something that could happen on my truck (it has SB 99-3-5 installed).


1- the trailer brakes might need work. Perhaps the safety brakes (there is a little battery in the elect. brake system) that activates the brakes if the trailer gets disconnected might have been active.

2- stop backing and investigate the problem.

3- yes

4- yes

Get under the truck and see if you can determine where the ATF “sprayed” from. Monitor ATF fluid level in the transmission until you have determined the source of the leak and corrected it. Perhaps a fitting on a transmission cooling line couldn’t handle either the pressure or the heat.

Thanks, UT.

Will check on the trailer’s braking system, but his wiring connection to the trailer does not have a line for the brakes.

We did check under the truck and the spray looked like it was coming from the rear seal. We will investigate further.

Also, he has a couple of add-on guages, one that gives transmission temperature, and the temperature was normal throughout the difficulty. I have to find out what the other guage is.

Some trailers (U-Haul for instance) have mechanical brakes activated by the trailer tongue. When the tow vehicle stops or brakes, the momentum and weight of the trailer compresses the trailer tongue activating the brakes on the trailers. Trailers of this type can be difficult to back when there is enough resistance to activate the trailer brakes (for instance – up a hill or on a sandy road). This may account for the increasing resistance as you back the trailer.

This happened to a friend of mine backing in a travel-trailer. The fluid was overheating due to the resistance of backing up a slight incline. His sprayed ATF out of the fill tube. Once allowed to cool, everything was fine. Checking the fluid the next day, it was only down a 1/4 quart.

One mechanic told him it was a quirk of the Ford Automatics to do this in reverse when the fluid gets too hot. Having to struggle to get the trailer in position like you did added a lot of heat the the ATF.

From what you are describing, I have no doubt that the fluid heated up tremendously. What temperature was the guage reading during the backing??