- Joined
- Oct 15, 2026
- Messages
- 1
- Points
- 1
- City
- POINTE-CLAIRE
- State - Country
- QC - CAN
- Vehicle Year
- 2003
- Vehicle
- Ford Ranger
- Drive
- 4WD
- Engine
- 4.0L
- Transmission
- Automatic
- Total Lift
- Factory
- Total Drop
- 0
Good afternoon to all! I'm writing to see if anyone with more knowledge than me on the subject of transmission rebuilds can help me troubleshoot an issue.
I recently rebuild my 5R55E transmission with a complete paper, rings and gasket set, new bands, new clutches & frictions and a transgo shift kit in the valve body. The transmission now operates flawlessly from gears 1 - 4. While driving I had suffered an external leak from my overdrive servo cover, which caused the transmission to overheat and burn up the overdrive band. As a remedy to this, I replaced the band, the overdrive piston and the cover O-ring. I made sure to tighten the O/D band adjuster to 10ft-lbs and back it out carefully by 2 turns before tightening the lock nut.
After the repair while doing my first highway test and logging with a high grade OBD scanner, I noticed that the overdrive would cease to engage and the real time gear ratio would fluctuate in an active region between 0.75 and 1 while the PCM requested 5th gear & 0.75. After about 10 minutes of highway, the fluid temp crept up to 108°C (226°F), so I shut off the truck and let it cool down. On the drive home I disengaged the overdrive and drove home in 4th gear, temps settled to 70°C (158°F). I think its a fair deduction to say that when the PCM requests O/D the band doesn't engage properly and starts to slip which overheats the fluid. From this, my best guess is that there is an internal leak in the overdrive hydraulic circuit.
I'm planning on removing the VB today and using compressed air to test the servo apply and release ports and see if the air leaks through the seal or bore. What other possible failures might there be specifically related to the overdrive hydraulic pressure circuit? What tests should I be doing to help narrow down my fault?
Any help or insight will be greatly appreciated!
Thanks,
Oliver
I recently rebuild my 5R55E transmission with a complete paper, rings and gasket set, new bands, new clutches & frictions and a transgo shift kit in the valve body. The transmission now operates flawlessly from gears 1 - 4. While driving I had suffered an external leak from my overdrive servo cover, which caused the transmission to overheat and burn up the overdrive band. As a remedy to this, I replaced the band, the overdrive piston and the cover O-ring. I made sure to tighten the O/D band adjuster to 10ft-lbs and back it out carefully by 2 turns before tightening the lock nut.
After the repair while doing my first highway test and logging with a high grade OBD scanner, I noticed that the overdrive would cease to engage and the real time gear ratio would fluctuate in an active region between 0.75 and 1 while the PCM requested 5th gear & 0.75. After about 10 minutes of highway, the fluid temp crept up to 108°C (226°F), so I shut off the truck and let it cool down. On the drive home I disengaged the overdrive and drove home in 4th gear, temps settled to 70°C (158°F). I think its a fair deduction to say that when the PCM requests O/D the band doesn't engage properly and starts to slip which overheats the fluid. From this, my best guess is that there is an internal leak in the overdrive hydraulic circuit.
I'm planning on removing the VB today and using compressed air to test the servo apply and release ports and see if the air leaks through the seal or bore. What other possible failures might there be specifically related to the overdrive hydraulic pressure circuit? What tests should I be doing to help narrow down my fault?
Any help or insight will be greatly appreciated!
Thanks,
Oliver
