I have 92 300E 4matic that has a reverse problem. Most threads I read talk about how it works when cold then dosnt when warm. My is the opposite. Dosnt work until the car has been driven for a while? B3 still probable cause?

Either way I am putting a new motor in the car soon and if B3 is my problem I was hoping some one had some info. A walkthrough of the procedure? A specific manual that might help. Tips? other parts?

Also is it just the piston that is replaced? Are there other seals or parts I might need related to it. And where can I find any of these parts online? I cant seem to find the b3 for sale anywhere..

Thanks for your help.
Brad