REPLACING A PILOT BUSHING IN A 2006 MERCEDES SPRINTER

By way of explanation for this blog post, I'd first like to reproduce my corresponding animated entry from Instagram:

Rant:  Multiple times, I have challenged both local mechanics and online forums (more than one!) to HELP ME CREATE A LIST OF EVERY TINY PART THAT WILL DISABLE OUR VAN WHEN IT INEVITABLY FAILS DUE TO AGE.  I would gladly pay someone to replace ALL such parts preemptively, if only they could be systematically identified!!  But all my efforts to date have been an absolute failure in this regard.  Seriously – I’ve taken this van to an MB shop and explicitly said, “Please replace EVERYTHING you think might fail, because one way or another, I will be doing those replacements, and I’d prefer to do them in one fell swoop right now.” With all the expertise I’ve tapped to date, every set of suggestions has totally missed the mark, including at MB.  Our latest headache is the failure of this $10 part that nobody called to my attention previously – but it isn’t even a $10 failure, it’s really a 3-cent failure because it’s the o-rings *ON* the $10 part that are the real problem.  This despite paying MB for a transmission servicing just 16 months ago!!  How do I surmount this barrier to efficient T1N Sprinter ownership? Maybe @millionmilesprinter will be the one who develops that elusive comprehensive list and offers that preemptive service to those of us who don’t want to keep repairing, and repairing, and repairing, ugh (fingers crossed).  

This replacement has been covered by numerous YouTubers and forum participants (the offending part is sometimes called a nag plug or transmission adapter housing - see here).  I just wanted to throw in my own pics and observations to round out the efforts of those who have come before me.

So what's the very first thing you do when confronted with the fact that your transmission has been leaking for an indeterminate period of time?  You check the oil level.  But guess what?  Mercedes Benz doesn't provide you with a dipstick.  Not if you own a T1N Sprinter, that is.

Why on earth would they not include such a basic piece of equipment?!

This is why.  "MB Workshop Only".  Which might not be such a bad idea if they were competent and could be trusted as a result.

It's because they don't want DIYers working on these transmissions.  But guess what??  I paid a Mercedes Benz shop several hundred dollars to service this transmission just 16 months ago.  Obviously they didn't do it properly if it began leaking fluid so soon.  

Listen to The Picard.

So then what do you do in a situation like this?  Well, having no idea how much oil leaked out of the transmission, you can't risk driving with too little, and you can't get it fixed unless you drive it to a place where it is fixable (I was not going to pay for a flatbed tow because of this fiasco).  So you take an educated guess.

Ultimately, our educated guess looked like this, which we found out several days later when an aftermarket dipstick arrived from Amazon.

Here's the description of that dipstick as it appeared on Amazon:  TRANSMISSION DIPSTICK TOOL w/INSTRUCTIONS & FREE LOCKING PIN Mercedes 722.6 Transmissions – Replaces OEM 140589152100

It takes a while to get the hang of this dipstick.  I can see why MB would not want uneducated DIYers trying to mess with it, because it's easy to get an erroneous reading.  But with enough iterations on both hot and cold engine states, you can get the "feel" of when you are getting a good reading.

It does not insert all the way in like an engine oil dipstick does.

OK, now on to the leak itself.  @MillionMileSprinter told me in an email that there was about a 99% chance that the pilot bushing was the source of the leak (with oil spread everywhere, we could not tell by looking).  So we ordered one of those.

Another reproduction from Instagram.  Why are we having to learn so much of what we know about our vans from a photo sharing site, for crying out loud?!  Theory says I should be able to pay one or more mechanics for that knowledge. 

By the way, failure of this $11 part is more serious than a loss of oil.  If the leaking oil wicks up into the transmission controller, it can put the Sprinter into permanent limp mode until fixed.  And of course, ours had to obey Murphy's Law and begin leaking in earnest shortly before a planned Christmas trip (we noticed it less than a week before).

Here's where that little device mounts on the curb side of the transmission:

Photo center.

It's a very easy job to swap this thing out.  Search for it on YouTube vids for more detail, but basically you rotate that thumb tab downward, pull out the black plug-like object with the wires attached to it, and unscrew the bushing:

Pop the new one in, re-tighten the screw, re-insert the wired module, and tighten down the thumb tab to seat it properly.

OK, so did the replacement of this $11 part solve our issue?  The proof is in the Christmas pudding:

Explain this crap - why couldn't Mercedes Benz have done this simple, simple thing 16 months ago when I paid to have the transmission serviced?

Either one of two things has to happen here in order to make the management of this issue professionally defensible:  Either Mercedes Benz has to include the replacement of such a common known failing part in their routine transmission servicing, OR, they have to tell customers, "By the way, it is not our policy to replace this $11 part on the transmission when we are doing a servicing for you.  You should expect that to fail shortly after you leave our shop."

Either one of those needs to happen to do right by customers.  But this example is just a symptom of a far wider phenomenon, and that is the paradigm of "We'll fix it when it breaks".  The paradigm is NOT what it should be, which is "We'll do what is logical and common-sense necessary to help you keep your van running reliably given that you are a paying customer."

As I said in my Insta-rant above, we are just not there yet.  Here's a screengrab from the resulting comment section, and I think this sums the whole situation up nicely.

"Local dealers are merely parts installers." Ouch.  But I have to wonder what the explanation is here.  This part commonly leaks on MANY Mercedes Benz vehicles - not just Sprinters (e.g., see here).  How could any MB shop either not know, or simply not bother, to replace this part as a matter of course?!

20190203 EDIT:  We checked the transmission control module to see if any oil might have gotten into it from the previously-leaking bushing described above.  Not a trace was seen.  This examination has been well-described by other sources, but here's a reference pic anyway: