E40D issues
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4wd High
Joined: Apr 2026
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E40D issues
I have a 1997 f250 7.3PS e40d 4x4. I have lost overdrive while driving highways speeds and significantly harder shifts in the remaining 3 gears almost as if line pressure was raised. At the same time this has happened I can hear a distinct whining noise coming from specifically the bell housing/torque converter area that becomes louder as rpms go up. also od/off light flashing. I am wondering if these transmissions have a limp mode and if the fault is in the torque converter and that is what has caused the loss of overdrive and higher line pressure feel? looking for diagnostic help and where to start. thanks.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,730
Likes: 2,658
From: SE Florida
The torque converter can't affect overdrive.
The ONLY way to fix this is to read the codes. Then we can help direct you to the problem. Anything else is just guessing, and will waste a lot of time and money.
The ONLY way to fix this is to read the codes. Then we can help direct you to the problem. Anything else is just guessing, and will waste a lot of time and money.
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4wd High
Joined: Apr 2026
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After finding that code I decided to clear it and try and reproduce the issue. I started driving it with codes cleared and it felt like it was back to normal again. no hard shifts, almost as if a "limp mode" was removed. everything seemed normal until it would shift into 3rd gear and i could feel it trying to engage converter lockup and it kept slipping and wouldn't lock. any thoughts?
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,730
Likes: 2,658
From: SE Florida
Clearing the code does remove the FMEM (Failure Mode Effects Management) aka, limp mode.
You most likely have a failure in the torque converter lockup system. Since you don't have an electrical code, we can rule out the PCM, wiring, and the solenoid. It could be a bad seal on the input shaft, a bad converter, or a stuck converter clutch control valve. The trans needs to come out to check each of these.
You most likely have a failure in the torque converter lockup system. Since you don't have an electrical code, we can rule out the PCM, wiring, and the solenoid. It could be a bad seal on the input shaft, a bad converter, or a stuck converter clutch control valve. The trans needs to come out to check each of these.
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4wd High
Joined: Apr 2026
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okay thank you. Are you saying that the p1728 code is not an electrical code? what does this code mean? on the scan tool I was using it just said something along the lines of "transmission slippage" and nothing to do with torque converter.
thanks
thanks
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4wd High
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I forgot to mention that after I cleared the codes, the whining noise coming from the torque converter/bell housing area had went away. That confused me a bit.
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Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,730
Likes: 2,658
From: SE Florida
The noise is from the pump. When certain codes are set, and P1728 is one of them, the transmission defaults to high line pressure. That can cause noise from the pump.
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4wd High
Joined: Apr 2026
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Thank you for that information. knowing all of this, when I go to put everything back together are there any upgrades or improvements I should be making to the transmission specifically on the torque converter circuit side of things to keep this from happening again? maybe increasing line pressure? Also, say I wanted to replace the factory torque converter with a triple disc converter, does this require any tuning or other upgrades?
Lead Driver
Joined: Apr 2016
Posts: 7,210
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From: Bahstun
triple disc is just the TC clutch like plates inside and OEM uses a single that can only hold maybe 300 HP according to interwebs
The stall speed on OEM is a bit high which creates more heat and the cooling system is oversized for this, the lower stall ones apply power at lower RPMs and reduce heat
There are seals, bearing and pump circuit mods that can be done.
The stall speed on OEM is a bit high which creates more heat and the cooling system is oversized for this, the lower stall ones apply power at lower RPMs and reduce heat
There are seals, bearing and pump circuit mods that can be done.
Fleet Owner
Joined: Jul 2006
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From: Mi'kma'ki
Thank you for that information. knowing all of this, when I go to put everything back together are there any upgrades or improvements I should be making to the transmission specifically on the torque converter circuit side of things to keep this from happening again? maybe increasing line pressure? Also, say I wanted to replace the factory torque converter with a triple disc converter, does this require any tuning or other upgrades?
The Installation Of Transgo's 'Tugger' Reprogramming Kit (Shift Kit For HD Hauling & Towing)
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4wd High
Joined: Apr 2026
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alright so I have torn down my transmission to the point of i think finding the failure. I cut open my converter and found the thrust bearing on the lockup clutch side to be warn horribly very significant grooving (little confused how this could cause slipping). the stator fins were all messed up. also, lots of friction material but surprisingly still material left on the clutch disc itself. I then cut open my filter and found metal shavings in it. i tore out the pump from the trans and found some slight grooving I could feel on the pump gear with fingernail. weird thing was the torque converter had a build date from 2004, but it looks like somebody had recently gone through the transmission because on the separator plate of the valve body it was all branded transtec which is aftermarket and looked very clean. I only pulled the overdrive clutches and steels and found to be perfectly fine, pretty much no wear like brand new. so, my question is, do you guys think i would be ok just changing the pump and converter and not tearing into the whole transmission or is the whole trans scrapped. I plan to put a tugger kit in it also. I also tore apart valve body and couldn't find anything on converter circuit to be damaged or stood out to me.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,730
Likes: 2,658
From: SE Florida
Unless you drive mostly with the OD OFF, or frequently use manual 1 or 2, the coast clutch is just along for the ride. It is only engaged with the OD OFF button pushed, or when the shifter is in the 1 or 2 positions. It is a very poor indicator of what the rest of the transmission looks like.