W126 Transmission Issue
 

I love my 560SEL. I just replaced the original 250K mile transmission with a used unit with 160K miles. It was fine at first, but now it shifts perfectly when cool, but loses gears when it warms up after about 20 miles highway driving.

I believe that this has something to do with heat, indicating a cooling system problem. My mechanic believes its a pressure issue with warmer fluid with lower viscosity causing the problem.

Can either of these issues be corrected wiutho9ut replacing the unit? Transmission shops seem reluctant to repair transmissions, pushing you to replace, which I'd rather not due twice in a year.

Any feedback would be appreciated!

I assume it is a 91 car?

What model transmission do you have?

You lose all the gears? correct? or will not drive out of first?

Martin

Well... it was a used unit. Did you drive the vehicle prior to install?

Are you certain the unit is full of ATF?

A used unit with 160k could be 160k of aggressive city miles....no way of knowing what condition it was in unless tested or inspected before install....always a gamble if buying untested high miles parts.

I've saved alot of money by removing trans my self,and buying the rebuild kit.Then let a trans shop rebuild it.I look for a shop that can rebuild Mercedes Transmissions.