No Reverse, 4L80E Any Ideas?
03-06-2006, 01:53 PM
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No Reverse, 4L80E Any Ideas? I have a 4L80E in my work truck.(01 3500hd 8.1L gas) Everything is working except for reverse. Fluid level is good. It is a little dark, but not terrible. This just happened, as in, this morning it worked, and right now it does not. You can put the selector into revers, and it just free revs like it is in neutral. any ideas? Any help is greatly appreciated.
03-06-2006, 04:21 PM
#2
My 1998 4L80E did this at 60,0xx miles.
First time it lost reverse it was because the servo apply pin was too short and the piston was bottoming out in the case. This time it moved a little bit.
Second time it lost reverse was sudden and it would not move at all. Line pressure was 500+ psi. It broke the reverse servo piston.
From what I learned high pressure parts breakage is common with a 4L80E.
One shop showed me a blown out oil passage in a case, and a direct drum with the piston seals blown out.
There are some checks you can do that require removing the valve body, but I have a feeling you might just take it to someone.
First time it lost reverse it was because the servo apply pin was too short and the piston was bottoming out in the case. This time it moved a little bit.
Second time it lost reverse was sudden and it would not move at all. Line pressure was 500+ psi. It broke the reverse servo piston.
From what I learned high pressure parts breakage is common with a 4L80E.
One shop showed me a blown out oil passage in a case, and a direct drum with the piston seals blown out.
There are some checks you can do that require removing the valve body, but I have a feeling you might just take it to someone.
