Change Leaky Transmission Connector

People talk about doing this frequently, but its not an obvious part to swap.

NOTE: This part is the same for 2002 and later (including 2012) Sprinters, so the process will be the same for all of them.

I noticed a leak under the transmission - when I popped under to see what the problem was, the passenger side (NAFTA) had a leak and it was coming from the connector junction.

I ordered 2 (1 as a spare) of these:

http://store.europarts-sd.com/transmissionadapterplughousing2002-2008.aspx

Removal ---

Once the connector sleeve showed up, I waited for a warm sunny January Colorado day (58 degrees) to swap the part. The service manual is pretty minimal about what to do. It looked easy.

I might add that its a screwy looking part.

I jacked up the passenger side so I could get under the Sprinter without too much trouble.

The lever on the sleeve (the one the show in the diagram) was jammed and it was a major effort to get it to move at all - it turned about 1/2 as far as it should, then I snapped it off - it was very hard to turn at all.

When you turn the lever, it moves the actual connector out of the transmission. I ended up breaking the part with the lever off and then working the connector out of the transmission. It was full of transmission fluid.

Now on to the actual part to replace. It has a threaded nut in it - I added some pictures showing that.

I used an extended socket to unscrew it. It is 7mm.

Yup. I *just* did this repair also. And yup, that stupid white/tan rotating cuff thing can be a BEAR to move. What should have been a quick 10 minute job turned into a 30 minute job because that cuff/collar/lever kept getting stuck.
Oh well, it all ended well enough. No more leak.
Nice photos.

Assembly ----

Once the part is out, I wiped down the opening where the new part fits in. It took a bit to playing with it to get it to line up. The lever on it should be down.

I had to jam a paper towel into the end of my socket to allow me to force the bolt that is in the connector sleeve to actually start tightening down.

Once in place, I wiped the connector clean and worked it into the connector. The lever (looks yellow in the picture) should start in the down position, but when you turn the lever to the up position, it locks the connector in place.

There is a black wire to holding a plastic sleeve onto the connector cover. I added some black electrical tape over this area, as the original sleeve had been broken thru (I suspect this might be the source of some shifting problems I had when it is wet out). I used white wire ties to hold the tape and connector cover in place.

I wasted a lot of time getting under and out again to get different things as I was not sure what I would encounter.

I spent 2 hours swapping this part.

Another good source of info is this thread:

https://sprinter-source.com/forums/showthread.php?p=21779&highlight=transmission+connector#post21779

Searching more might find even more info.

A postscript to the tech info for socket/o-ring replacement:

The replacement socket (w/the latest black Viton o-rings) can be VERY difficult to fully seat in the transmission housing. The latest o-rings are challenging to seat because they are more resistant to compression during installation.

It is important to visually memorize the approx. protrusion of the old socket past the trans housing and make sure the new one is fully installed to that same depth.

Lube the o-rings and never use the center bolt to fully seat the socket.

It is OK, once socket is radially indexed for installation and partly inserted, to gently strike it square across the face, to full depth, using your big ratchet's handle.

Doktor A

I did that just now - before and after pictures. Roughly 1/4 of an inch more (6mm) moved into the transmission.

I popped it out - cleaned it and re-lubed the o-rings before putting back in.

I used a small block of wood and a hammer to get it in place. It would not go any further.

I used a mirror to verify that there were no bent pins and could feel them with my finger tips after installing the sleeve.

After changing this part, I noted that I had transmission fluid on my Transmisson Control Module (TCM), which is at least 5 feet of cable away from the transmission connector - the TCM is under the drivers seat, way above the transmission. The oil appears to wick up there.

I have read about this problem on this forum before (and it can damage the TCM). I also looked online and found its a common problem with other Mercedes automatic transmissions (I am sure other vehicles have the same problem), however it looks to me like it might be preventable.

When I crawled under the Sprinter, the transmission connector wires were very oily. Online, other people used Brake Cleaner to remove the oil on these wires.

The wires run thru a corregated black plastic tube from the connector, so, if I could de-grease it, and plug it, I suspect the problem will not re-occur again. This is what I did (and hopefully it will work):

Note: I put a pan under where I was working, because it would get messy.

I bought a spray can of Brake Cleaner and CRC Lectra-Motive. Both are supposed to de-grease withouty residue. They both had tubes that could be attched to the spray heads to direct the flow.

Note: I needed one hand to take the pictures, so I can only show what I was doing.

Cleanup ---

I cut the wire ties holding the cable to the tube at the edge of the transmission. I also cut the wire tie at the end of the connector. This allowed me to pop the top off the connector. I then cut back some of the black corregated tube that went into the connector - a few inches worth. I pulled the wires thru the frame so I could hold the connector up high to fill and low to drain.

Then I flushed out the inside of the connector (draining into the tub). Then pushed the cleaner tube into the black corregated tube, held the connector up high and filled the corregated tube with fluid. After 10 seconds, I drained it (lowering the connector) and repeated this 4 more times. I then slid the corregated tube up and wiped the wires clean and dry with a paper towel.

After everything was dry, I did not feel any oily surfaces on the wires or tube.

Re-assembly ---

I used a tube of RTV and trimmed the tip to allow me to add a tiny amount at a time.

I slid the corregated tube up, seperated the wires and started filling the areas between the wires with RTV - I wanted a good seal. Then I added RTV to the outside of the wires. Then I slid the corregated tube down, and filled it some more.

I added some new corregated tubing (its the blue stuff you see) - this was split so it could go over the old corregated tube. It goes down about 1 inch into the connector (the original corregated tube did the same thing). I snapped the top onto the connector I used wire ties (white ones in the picture) to hold the connector together, and to hold the blue tube in place. I also reattached the black corregated tube back on to the metal transmission tube.

The goal is to plug the black corregated tube and seal the wires so they don't wick anymore.

I used the same cleaner on the TCM wires and connectors too (putting down paper towels before spraying) - under the drivers seat.

Thanks for the update.

My experience is that when oil or other liquid travels other than downhill in wire harnesses it does that by capillary action. It is the close proximity of the stranded conductor within the wire insulation (the "tube") which sets the conditions for the liquid to move that way. I've seen some creep along the outside of the insulation (the "tube"), but to travel any distance up hill it is most likely moving along the inside. YMMV.

Regardless, replacing the connector should correct the problem. vic

Added:

Aqua Puttana said:

Some recommend a partial slow change out schedule if a transmission hasn't been regularly serviced. The concern is that a complete change out can flush junk free or somehow otherwise shock the system.

I have no data. I'm merely being a parrot. Good to hear that it seems to be working for you.

vic

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Added:
I have some tips for the Connector Body install.
Don't use the bolt to try and pull the connector into place. The bolt threads into a fitting on the circuit board. It is fragile.
Align and push the connector body in as far as it will go. After mostly in, use your fingers with the 7 mm socket to thread the bolt in until finger snug.

Note: The bolt sticking out prevents full seating. Screwing in the bolt finger tight and just pushing on the connector may yield similar results as my screwdriver levering method. The leverage made me feel better about fully seating without any strain on the circuit board screw mount.

Hold a kinda long chunk tip of a 2x2 against the tranny housing recess. Use a large screwdriver against that to lever/move the connector body in without forcing. Use the socket and your fingers to turn the screw in again. It should turn in some. Alternate the screwdriver pressure to opposite sides of the connector.
Repeat the above procedure until the screw no longer turns in using your fingers.
Use a ratchet handle to snug the bolt in. Try the 2x2 and screwdriver lever procedure one last time. Check that the bolt is still snug. If snug, you are done. DO NOT OVERTIGHTEN.



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Thank you..A lot of help..Will pick-up or will order the elect. connector part.

Thanks for the pictures & info. I had a leak right after changing the trans fluid. I figured it was the pan gasket, it wasn't. I ordered the O ring & connector, w/ the pictures & write up it went EASY!
Thanks,
Matt Murphy

I just did the transmission connector and full service ie: changing the trans fluid and filter, It was relatively straight forward, I did however find it necessary to loosen the trans mount bolts and pry the transmission up just a bit to get the pan off and on.

when doing the connector I was able to jiggle it off and then re-install the new one by pulling it down and jiggling it a bit to get it to seat , then tightening the 7mm bolt down, all,s well,

thank you all for all the info.

freeman

So about 5 months ago I installed a new connector. I noticed now it has developed a small leak. My question is can I clean it and tighten it down or do I have to replace the whole thing since it may be contaminated with fluid??

mawsea said:

So about 5 months ago I installed a new connector. I noticed now it has developed a small leak. My question is can I clean it and tighten it down or do I have to replace the whole thing since it may be contaminated with fluid??

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Did you replace the connector socket liner, or the male part of the connector (w/ external wires going to the TCM under the driver's seat)?

I replaced both parts.

mawsea said:

I replaced both parts.

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If the plug is leaking at the wires, then I would at least replace that part (w/ new wires) since failure there could result in transmission fluid being transported to the TCM underneath the wire insulation.

mawsea said:

I replaced both parts.

Click to expand...

I take that back, I only replaced the transmission adapter plug housing. If that makes a difference? I'll look for ATF fluid traveling up the wires.

So, if the part you changed is leaking again, I would conclude that it is defective or wasn't installed correctly. I would install a new one. For comparison, mine was changed by a Dodge dealer at 55k miles and has not leaked since.

I've been noticing tiny puddles of trans fluid on my garage floor for the past month and so I decided to do this today. I was expecting the worst after reading everyones experiences but, to my surprise, everything went like clockwork and I had it all done in 15 mins!

The old connector came right out with no effort at all (O rings included) and all I had to do was tap the new one in the last 1/8" very gently using a small piece of wood and it went right in. I ended up adding 200 ml of trans fluid to bring it up to the 80c mark @ 175f engine water temp on the dipstick.

Thanks to all for this writeup!

An old thread, but served me well today, and I must give credit to abittenbinder and jmoller99 for their excellent tips on what to watch for, aligning the socket, and especially using a small block of wood to tap the new socket in.

It took me about an hour to do mine, (and that is on my hoist), so kudos to you all who did it in less time with your Sprinter on the ground.

When done, I added almost a liter of oil, so I lost quite a bit yet the transmission appeared to be functioning just fine.

As for that connector and socket, as I was working on this job, I couldn't for the life of me think of the rationale for Mercedes engineers to go to make such a complicated connector.

On a positive note, it is fortunate they made it readily accessible.

Thanks again to those who go out of their way to share their experiences and help others on this forum.