During our dig, it seems there is a leak coming from inside the Transmission Oil Temp Sensor creeping out from the wires/plug inside of it 92860615200. Has this ever been seen before? Is the part available through MB? I could not find anything besides replacing the part from Porsche.

 

14 potential leak points on a Mercedes 722 transmission-
plus the pivot pin for kickdown fulcrum

the temp sensor not mentioned in this-
As I found out the leaks on these transmissions can easily look like they are coming from a different source-

 

I saw this video earlier, but the case is different from Porsche’s. As you can see, the plug area for the Protection Switch on the Benz is sealed with a plug and right above it is where on the 928 you have the ATF oil line with the Temp Switch located. My mech saw ATF coming out from the black plug on the sensor and flowing out. Could also include the washers on the banjo bolts, but he was confident it was from inside a failing switch...

 

I did some research on this switch for another purpose, and found several similar besides the one that's on the car. I was looking specifically for a sensor that offered a temp gauge connection, in addition to the high-temp switch closure function. It's a Bosch Group (VDO) switch in the car now, and can be found readily from our suppliers. Since it is external to the gearbox itself, and intended only to support the cooling fans in S4+ 928 models, you may not find it at a Mercedes parts counter. Know that the switch fits into the transmission cooler hose connection on the left side of the 928 gearbox. It has an aluminum ring seal of its own where it threads into the banjo block, which can leak. The Porsche-supplied switch includes the wiring pigtail that passes up to the connector in the spare tire well. A VDO (non-Porsche) replacement has a spade connector at the switch, so you'd get to modify the wiring there slightly.

 

Hi Dr. Bob,

thanks for the feedback. I believe at some point in its life, the sensor on my car was replaced by something as the wiring harness is hacked. Additionally, there was no washer between it and the banjo as well. As a temp fix, we went ahead and sealed the black plug with silicone to reduce the leaking. I ordered a new one and washers online and will replace it along with the full wire as I am not a fan of electric joints specially under the car where elements take their toll.