e39 auto trans compatiblity between 2002 520i and 1999 523i

[mons2b 0]

Hi

Wondering if anyone here knows if a automatic transmission from a 2002 M54 520i e39 would work on a 1999 M52TU 523i? I know the engines are different but I believe both are the same transmissions with the same transmission model number. The only difference is end of the part number varies slightly between 520's and 523's and 525's.

Im taking a educated guess and thinking maybe they are setup for different engine torque ratings?

None the less if bolted up would it work or would the ecu reject it with a christmas tree of error lights?

Edited November 5, 2015 by J B W

[mons2b 0]

Hi

Wondering if anyone here knows if a automatic transmission from a 2002 M54 520i e39 would work on a 1999 M52TU 523i? I know the engines are different but I believe both are the same transmissions with the same transmission model number. The only difference is end of the part number varies slightly between 520's and 523's and 525's.

Im taking a educated guess and thinking maybe they are setup for different engine torque ratings?

None the less if bolted up would it work or would the ecu reject it with a christmas tree of error lights?

No ideas anyone?

[Allanw 1071]

Sorry - I can't really help either, but...

It might work... but you'd really have to know what trans is in what car, and that can vary by the market it was made for.

You could look them up by chassis number, and see what they should have had, on RealOem or similar.

You also have to be a bit careful, because the Japs had a 525i which was really a 523i, and wasn't like the M54 525i at all. There were the M52 engines, AND the M52TU's. I couldn't tell you the differences about the trans, but very early E39's are just about an entirely different car to the late ones, from an electronics point of view.

Some of the transmission codes changed, JUST because they went from proper oil changes, to "sealed for life" - even though the trans might be functionally exactly the same, there is no dipstick etc. It's a hard call to make without being REALLY sure.

It's a lot of work to fit a used trans, then discover that some guy you don't know, who said it was going to work, was wrong... on the internet... practically never happens

Find a manual box and cram that in

[Ahmedsinc 414]

I have read that the Japanese E39s followed a similar trans path as the E36 - licensed Jatco boxes in the early to late 90's cars then solely ZF transmissions from the 2000's onward. No idea how accurate the info is but it wouldn't surprise me if correct.

My guess would be the M54 trans wouldn't run with the older TCU. Far better to find a good transmission from a matching car or have the current one rebuilt (if salvageable)