4l80e
Thread Starter
Teching In
Joined: Jul 2013
Posts: 22
Likes: 0
4l80e I have a 4l80e that was just rebuilt by a friend, I was there during most of the rebuild process and it seemed fairly straight forward and seemed as if a good job was done. I have installed it now, and it has virtually zero line pressure you have to floor it to get maybe 50 psi in drive after which it will move. The fluid is already black with metal everywhere (think its fried again) so I took it out tonight. After 4+ hrs of sitting the torque converter was still scorching hot, I couldnt leave my hand there for more than 2-3 seconds. Even the engine block was cold. Is this normal? Nothing else was even warm besides the tranny being barely luke warm, yet the converter was blazing hot. I would also like to mention all new electronics were used. Other issues were everything was like drive, neutral was drive even reverse was drive. at first it would move forward in reverse but if enough throttle was applied it would seem to bind as reverse engaged. The tranny originally had burned forward clutches which was reason for rebuild, shift solenoid A literally fell apart upon removal, which was probably part of the reason the forwards were burned. My buddy said it was probably ok to reuse the torque converter even though the forwards threw metal everywhere. I was sort of wondering about that but didnt have money to buy another so decided to risk it (brilliant i know). What else could have caused the burned forwards could it be the same problem? The tranny was high mileage (427k miles and yes this was first rebuild i'm positive)
Last edited by Gearhead115; Jul 31, 2013 at 12:12 AM.
The used converter, that came off the trans with failed forward clutches probably nearly immediately filled the trans pump with sand like grit that caused the pressure regulator valve to stick at minimal line setting. No pressure, you get some slight pressure at higher pump speeds due to the volume.
This is why you don't use a used or contaminated converter on a fresh rebuild. Hard lesson to learn. I got to "re-learn" it recently when a vendor did a flush on a converter and not a cut and clean.
4L80E's have a very solid forward clutch circuit and design, they only fail when there is a low pressure condition.
This is why you don't use a used or contaminated converter on a fresh rebuild. Hard lesson to learn. I got to "re-learn" it recently when a vendor did a flush on a converter and not a cut and clean.
4L80E's have a very solid forward clutch circuit and design, they only fail when there is a low pressure condition.
Thread Starter
Teching In
Joined: Jul 2013
Posts: 22
Likes: 0
Thank you for confirming, I suspected that might have been the issue. I'm sure it didn't help i drove it 3+ miles in that condition either.. So what might the original cause of failure have been? 427k miles it started out hesitant to go into first gear, slowly got worse. Later it hesitated and shuddered between 1st and 2nd. and finally it shuddered and slipped in all forward gears and shifts. Upon tearing it apart the only damage was to the forward clutches.
I'm assuming that the reason im getting drive in all gears is welded or seized forwards due to low line pressure and attempted driving?
And about the new electronics I put in.. do you think they are toast or would they stand up to the onslaught of debris? Sorry for all the questions
I'm assuming that the reason im getting drive in all gears is welded or seized forwards due to low line pressure and attempted driving?
And about the new electronics I put in.. do you think they are toast or would they stand up to the onslaught of debris? Sorry for all the questions
Last edited by Gearhead115; Jul 31, 2013 at 02:03 AM.
