W126 Tranny Fixed!

[Ed1Sinclair]

After some 2-3rd flaring, no fourth gear and loss of forward drive the old 380SE has been reborn. Yes it is possible to repair a Mercedes Benz automatic transmission even without removing it from the car.
First step was head scratching and mild depression at the cost of a replacement unit with a "reconditioned" one.
Then some investigation and net-surfing to assess my options.
Thirdly, lots and lots of research and diagrams (all on the net).
Fourth was budgeting. Parts came to $450 AUD, including $150 for tools.
Finally, a day in the pit under the opened auto box.

As prescribed by various sources (thanks to all!!!) the 2-3 flaring was probably fixed by a replacement K1 kit. Fourth gear is still a mystery but I think was revived by very carefully opening the valve body and cleaning it out. Forward drive was most obviously the B2 piston which had broken into at least six pieces (typical catastrophic B2 piston failure at 220000kms/135000miles). The most tedious part of the operation was removing the old piston seal and metal sleeve. Opening the valve body was risky but I think paid off.

The tranny fluid pan was very clean upon initial inspection so I decided to go ahead with the job since this indicated there was probably nothing else major wrong.

The kick-down (bowden) cable sits at around 1mm play at throttle rest. I did turn the modulator adjustment anti-clockwise 1 turn for softer gear changes.

Now to get some miles on the old girl while fuel is still affordable!