1993 C3500 454cid 4le80 trans, no overdrive

hillbilly135 · March 8, 2015

Greetings everyone!

I just purchased a 1993 C3500 dually with the 4le80 transmission.

I purchased it knowing the OD DID NOT work.. transmission shifts all gears fine, except OD.

Put in a pint sized container of the SeaFoam Transmission Tune up just for fun, as I am thinking a re-con transmission anyhow.

The next day, as I was driving to work in it, the transmission shifted into OD and ran for approx 4 miles... worked like a dream.. did not downshift except when it needed to. BUT, when it DID downshift, would not go back into OD again. (Until the next morning...)

SO, it seems as though the OD does work... when it wants to.. also has a code of 68 in ECM (cruise system problem)

Am I still looking at a re-con transmission or, is there, perhaps, a cheaper alternative?

P.S. Transmission cooler lines are SEEPING at radiator.. nothing serious

Transmission fluid appears clean with no burnt smell.. not sure about filter though..

I hope that I have included enough details for you techs out there to help..

Thank You..