The plug for the transmission is leaking. It was changed in July 2013 after it had been leaking for some time. It has not leaked since then. A few days ago the vehicle began having shift problems while out on the road. At home upon parking the vehicle a LARGE puddle was observed under the car. It appears the plug is leaking again. Upon putting the car up on ramps and removing the plug about 1 pint of fluid drained out is that normal ? Can i spray contact cleaner on the pins or will that get into the transmission ?....any ideas on the premature failure of the plug?

THANKS ROD

the electrical plug i am referring to is called a transmission pilot bushing.

Rod

722.6 transmission does not like incorrect fluid levels - apparently less than a pint of fluid loss causes major problems.

Yes the electrical connector is known to leak. In order to change it out you'll probably need to drop the pan.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

My understanding is that they updated the plug design several times over the years and that the recent designs are much less prone to leaking. That said, I'm still tempted to replace the plug every time the filter is changed just for peace of mind.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

As to how sensitive the 722.6 is to fluid level....when I got my 98 I noticed it was leaking fluid. I think I probably added a good quart or so (certainly no more) to bring it up to level but I never noticed any degradation of performance in the time I drove it with low fluid.

__________________
14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Shertex, it appears that it is losing a large amount of atf, could the conductor plate where the pins are located be damaged ? or is it more likely that the pilot bushing 2 black o-rings be bad after 17 months....the o-rings upon inspection seem to look brand new.

Not sure...perhaps others who are more knowledgeable can chime in. Hard to imagine those o-rings could be bad after such a brief period.

How many miles on the car?

__________________
14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

The vehicle has 156K miles on it. Aprox. 13k since the last pilot bushing was installed.

So you are saying you removed the 7mm bolt and pulled the pilot bushing out and 1 pt fluid came out? Or you just unplugged the electrical connector and 1 pt fluid came out?

I'm not sure what happenes when there is fluid in there and you pull the pilot bushing. But i'm guessing fluid would come out. I've always drained pain first. Maybe it was overfilled? Thats a lot of fluid to leak out past those orings. It could be pan gasket, cooler line, dipstick tube connection. I just changed mine and it had a little fluid outside of it but not puddles.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

Biopete, the car is on ramps tilted front to back. upon removing the electrical plug "cap" it started leaking, upon removing electrical plug the leak speeded up, upon removing the 7mm screw and pulling the bushing out the leaking continued until it became a drip.......if i add atf now with the car still on the ramps and bushing back in and electrical plug out i am assuming it should not leak as the plug has the red o -ring for dust and the bushing the 2 black o-rings as a seal against atf leaks. Is this a correct assumption?

The connector does have o-rings for the purpose of holding back the fluid. The pins on the plug run into the "conductor plate", which holds the solenoids and sensors that control the transmission. The plate is in the "wet" area inside so there is ATF behind the plug.

The reason I suggested dropping the pan was to inspect the condition of the conductor plate since it seems to me that something may be damaged in there causing a poor seal.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Jay Bob, exactly what i did not want to do since i changed atf only 17 months ago.....will probably order a new bushing refill and test if not will have to do as you say.