Transmission
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Joined: Apr 2019
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From: Wheeling, WV
Transmission
I have a 2019 f-350 SRW with the 6.7 diesel with 46,414 miles. It has the 6R140 transmission. All was good up until yesterday. After using my truck all day on Tuesday, parked it in garage. Yesterday, all of a sudden it won't shift from 3rd to 4th (unless you "finesse" it using the accelerator pedal). It does shift from 1-2 and 2-3 perfectly and 4-5 and 5-6 perfectly. Once I do have it in 4th, it has plenty of power, so assuming, no slippage? Fluid level is spot on, but has the color of chocolate milk. So, I drained the fluid, removed and cleaned all 7 of the solenoids, changed the filter, and refilled with fresh Mercon-LV hoping that would resolve the issue. But it didn't. I do daily towing, trailer is light at only 6720 pounds. I use it for snow plowing (truck has snow plow package). Any thoughts/ideas/suggestions on what is causing my truck not to shift from 3-4? TIA
Cargo Master
Joined: Mar 2004
Posts: 2,220
Likes: 1,423
From: CA
Since you mentioned chocolate milk, maybe the Transmission cooler (in radiator) is leaking coolant into the trans fluid? Or it's just so burnt that it extra dark? Either way, probably have an issue with 3-4 band and need a rebuild.
Posting Guru
Joined: Feb 2018
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Can you manually shift it through the gears? If it works fine manually, it's not likely to be a solenoid. You can try a logic reset. You owner's manual describes how to put the trans back into base level adaptive mode. I'd tell you what it says for my '18, but your '19 could be different. It sounds like it's skip shifting, which could be quite normal but I don't know if that is a programmed feature in that transmission. I don't pay attention to it. As long as it's pushing me forward, I'm good to go.
Lead Driver
Joined: Nov 2005
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The chocolate milky colored fluid is a big problem, and unless you had a flush machine or ran lots of extra fluid through it with the cooler line off to get all that contaminated fluid out, then you've still got a bunch in there.
Did you run the truck through deep water? Because the milky fluid really sounds like water contamination.
And, the shifting issue sounds like a bad shift solenoid, possibly due to the contaminated fluid.
Did you run the truck through deep water? Because the milky fluid really sounds like water contamination.
And, the shifting issue sounds like a bad shift solenoid, possibly due to the contaminated fluid.
Posting Guru
Joined: Feb 2018
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Maybe I'm messed up on this, but transmission pressure is substantially higher than cooling system pressure and the milkshake would be in the coolant, not the trans fluid. I don't know what he's seeing or what's causing it, but, yeah, let it be Ford's problem.
Lead Driver
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Hotshot
Joined: Dec 2005
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From: Chino Valley, Arizona
both systems were bright pink from the mixture.
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Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,695
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From: SE Florida
When the engine is running, you're right, transmission pressure is higher than coolant pressure. But when the engine is off the trans pressure goes to zero in a second or two, and the cooling system will hold pressure until either it leaks out or the engine cools back to ambient temperature. And that forces coolant into the transmission.
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