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expedition 4r70w 4th gear issues

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Old 07-16-2013, 03:24 PM
usaf_yz426 usaf_yz426 is offline
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expedition 4r70w 4th gear issues

Hello everyone,

I have a 2005 ford expedition with 91000 miles, it has the 5.4 w/ the 4r70w transmission.

For some reason when my truck tries to shift into 4th gear, the RPM's climb to approx. 3000 rpms (meanwhile the truck is not gaining speed) and slowly drops down to about 1000-1500. once the rpms drop down fourth gear eventually engages and I can go about my business as normal as long as I do not let my mph drop too low.

If I turn O/D off, the truck drives perfect, minus not having overdrive.

If I come to a dead stop and put the truck in 2nd gear, with O/D on the truck drives great and it has good engine braking so I am assuming that the band is holding.

I took it to a transmission shop to have some diagnostic checks done, they told me that fourth gear was barely engaging and that they would have to tear apart the transmission to diagnose it further, I told them not to disassemble the transmission.

So I changed out the torque converter (which I assumed was "fourth gear") and changed out all the fluid, the fluid looked a little burnt but there was no debris in the pan but there was some silver material on the tranny pan magnet, and installed a new filter. and the problem still exists. I am stumped and was hoping someone could provide a little insight.
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Old 07-16-2013, 07:55 PM
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The torque converter is NOT fourth gear. That was a waste of money.

You have a problem with the overdrive band. That band engages fourth gear. There is a clip in the overdrive servo which applies the overdrive band. This clip often breaks and overdrive will do what you're seeing. It and could also be burnt.
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Old 07-16-2013, 09:27 PM
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darn, thanks Ford dealership for telling me that the O/D is "4th gear".thanks for clearing that up for me Mark. would it be worth changing out the band, or just getting a remand transmission? I knew I screwed something up when I was towing my 4k lb travel trailer with the O/D on. Expensive lessons I tell ya.
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Old 07-17-2013, 08:17 AM
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OD *IS* fourth gear. Neither OD nor fourth gear is located in the torque converter.

It may not be the OD band. It could be the servo clip.

The truck should have no problem towing 4k pounds in overdrive.
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Old 07-18-2013, 11:59 AM
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The direct clutch could be starting to slip. Either way it needs to come out and be torn down for diagnosis.
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Old 07-18-2013, 10:10 PM
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every now and then second gear will slip a bit, but it slips in forth every time. Im probably going to take it to AAMCO transmission, the Air Force doesn't give me much time to tear my vehicles apart, instead i'm tearing apart airplanes and fixing them.
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Old 07-19-2013, 06:35 AM
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Quote:
Originally Posted by usaf_yz426 View Post
every now and then second gear will slip a bit, but it slips in forth every time. Im probably going to take it to AAMCO transmission, the Air Force doesn't give me much time to tear my vehicles apart, instead i'm tearing apart airplanes and fixing them.
AAMCO? I wouldn't let them flush my toilet.
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Old 07-22-2013, 03:37 PM
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well, the verdict is in. Because i burned up the lock-up in my torque converter, it ended up sending fine silver metal debris throughout my transmission. That ended up messing up my O/D servo and O/D band. Life is full of lessons, and this one taught me to tow with the O/D off.
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Old 07-22-2013, 03:37 PM
 
 
 
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