4l80

clrussell

pro-procrastinator
Sep 23, 2013
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I acquired another truck last weekend. Early 90s 6.5 auto truck
Trans was rebuilt a couple years ago by a local guy, shift great and all works as it should until it gets warm. And you’d probably never notice the problem other than towing in a field where you pull it down into low gear.

If you do pull it down to 1st or 2nd it won’t hold back after the fluid gets hot.

Anything easy/ common to look for? Is it something that can be fixed in the valvebody or is it deeper?

This trucks primary use was a farm truck for the last 10 years, and honestly will be just a beater for around town so if it’s to major I’ll probably just run it as is because I don’t really need it to hold back unless it’s hauling hay down a mountain with no trailer brakes.

pic for reference
 

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JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,714
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Texas!!!
They have an overrun clutch that does engine braking. If there are no other problems, I wouldn't worry about it.
 

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
15,681
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Fullerton CA
Could be rear band. The reverse band lugs are known to push themselves out of the case.