FYI for tranny malfunction

[TheFixer]

Here's an FYI for those with the 6AT. I lost forward and reverse yesterday just out of the blue. No codes at all.

I dropped the pan and mechatronic valve assembly and found my bridge seal cracked.

This will cause a no forward or reverse issue.

It is pretty brittle after 140k miles.

I think the failure may have been accelerated due to changing the fluid last month.

Anyway, if you plan on doing a filter and fluid change you should go the extra step and change the seals and mechatronic valves because it's right there in your face.

That's all folks.

 

[derekgates]

That is wild! Thank you for the post.

 

[TheFixer]

That is wild! Thank you for the post.

Yeah.... the smallest things break these cars hard.

Glad I can fix things.

 

[TheFixer]

Forgot I posted in two sections..... I'll update here too then.

Finished the valve body rebuild last week with a Sonax zip kit, ZF seals and ZF solenoids. Can't believe how much smoother and responsive the trans is now. With xhd in stock flash I can't even feel the car shift through the gears. Well worth the time and money.

Not difficult to do and quick to do.

Put this on your list of mods even if you think the trans is fine. The parts in the sonax kit are a huge improvement of what's in the stock valve body.

 

[derekgates]

Forgot I posted in two sections..... I'll update here too then.

Finished the valve body rebuild last week with a Sonax zip kit, ZF seals and ZF solenoids. Can't believe how much smoother and responsive the trans is now. With xhd in stock flash I can't even feel the car shift through the gears. Well worth the time and money.

Not difficult to do and quick to do.

Put this on your list of mods even if you think the trans is fine. The parts in the sonax kit are a huge improvement of what's in the stock valve body.

Oh I bet, those are some critical parts.

I don't have AT, but instead DCT and I was having driveability issues. I decided to do filter and fluid change... and it actually helped quite a bit! Sounds like a similar revelation to your experience.

 

[seb.apprenti]

Forgot I posted in two sections..... I'll update here too then.

Finished the valve body rebuild last week with a Sonax zip kit, ZF seals and ZF solenoids. Can't believe how much smoother and responsive the trans is now. With xhd in stock flash I can't even feel the car shift through the gears. Well worth the time and money.

Not difficult to do and quick to do.

Put this on your list of mods even if you think the trans is fine. The parts in the sonax kit are a huge improvement of what's in the stock valve body.

hi my friend, i have a question for you
in a few days i will drain my 6hp21 and replace the mecatronic seals.
apparently it is recommended that the oil be at operating temperature for the change, but my car is immobilized for the moment. it poses a problem to do it without reaching the temperature?

 

[TheFixer]

hi my friend, i have a question for you
in a few days i will drain my 6hp21 and replace the mecatronic seals.
apparently it is recommended that the oil be at operating temperature for the change, but my car is immobilized for the moment. it poses a problem to do it without reaching the temperature?

The car needs to be running when you do the final fill procedure and the transmission at required temperature. You have to cycle through the modes as well before final fill. Then fill, run through the modes again, and check fluid again. Otherwise you won't have the proper amount of fluid in the system.

There's quite a few threads on proper fill procedure on various bmw related forums. It's a pain, but critical you get it right.

 

[seb.apprenti]

The car needs to be running when you do the final fill procedure and the transmission at required temperature. You have to cycle through the modes as well before final fill. Then fill, run through the modes again, and check fluid again. Otherwise you won't have the proper amount of fluid in the system.

There's quite a few threads on proper fill procedure on various bmw related forums. It's a pain, but critical you get it right.

okay
but to remove the oil, we don't need an X temperature?

 

[TheFixer]

okay
but to remove the oil, we don't need an X temperature?

No. It will just drain quicker when warm. That's all.

 

[TheFixer]

okay
but to remove the oil, we don't need an X temperature?

Sorry, I didn't understand you meant just for draining it.

 

[seb.apprenti]

No. It will just drain quicker when warm. That's all.

perfect
thank you very much for your quick response