1997 E420 Trans
 

My E420 trans will not shift out of first gear after 175,000 miles. I am wondering if I should have my trans re-built or buy a "Factory" rebuilt trans??????????????? I am located near Chicago and am looking for advice on the best way to go for the money and reliability. How much should I expect to pay either way?

It sounds like your 722.6 is in limp home mode. Do you have a CE light? Can you move the shifter through the gears (though it stays in first)?

I have heard of some of the early 722.6's having faulty conductive plates causing the tranny to go into a "permanent" limp home mode and is locked in first, and sometimes fifth gear.

For a good diagnosis, you'll have to go to someone with the SDS sytem so they can access the tranny system on board. Before jumoing in and buying a new tranny (the 722.6 might not be available from rebuilders yet...?) you should see if the one you have can be fixed without a total tear-down.

Has the tranny been serviced along the way? There is much debate about whether or not to service the 722.6 since MB declares it "set for life" though they don't define what they mean by "life."

My belief is that MB's defines "life" as the warrenty of the vehicle.

My cousin works for Borg Warner, and a co-worker defined life of their transmissions as 100K miles.

I consider a vehicle dead when it goes to the bone yard.

There is also the possibility that the range recognition switch is not functioning properly. The limp home mode keeps in 2nd gear. Do you mean it is stuck in 2nd gear or 1st?

I have seen a 722.6 stuck in first gear in limp-home. Though incorrect, it seems to happen. I met another member whose car was locked in fifth.

There are a few problems that it could be that do not require major surgery, but without the SDS diagnosis system, it'll be tough to tell. Heck, even with SDS, it can be tough. Early conductive plate failures were often misdiagnosed by many techs. It's a guessing game for us on the forum. Hopefully our stricken member will keep us informed...

The fix for mine was to disconnect the negative battery cable for a minute or two. Hooked it back up and all has been well. This happened to me about a year ago.

Len
'99 E300TD 60,000 miles

Thanks for all of your replies. My trans is shot. After 175,000 my local MB dealer is rebuilding it for around $2,000. Is it a must to use only MB synthetic fluid?

Yes.Yes.Yes.Yes.Yes.Yes.Yes.Yes.Yes.Yes.Yes.Yes.

Was the trans ever serviced along it's way?

Yes with Amsoil. Once at 75,000 and then again at 160,000.

Interesting. Did you change the fluid yourself? This might be an example of the incorrect fluid leading to an early demise of the 722.6. 175K-miles seems like decent life, but I have seen and heard of many 722.6's going much farther with little care.

Is the work being done by a dealer? I haven't seen too many dealers willing to rebuild trannies, installing factory rebuilds instead. The price sounds pretty good compared to a brand new 722.6. Perhaps there are no factory rebuilt 722.6's available?

Agreeing with John, Amsoil is not an approved fluid for that tranny to the best of my knowledge. My fluid spec sheet says that there is only one approved fluid for the 722.6, the MB fluid, it MUST MUST MUST MUST be used.

I think this is an answer to your question, John, about if any have been serviced improperly. It is interesting that it did go over an additional 100k miles with the wrong fluid.

Always use only the MB approved synthetic fluid in the 722.6

My understand is, and I may be wrong, is that the wrong fluid leads to degrading of the clutch packs. I have no idea of why, but that is something a tech once mentioned to me. He also thought that the factory fluid allowed greater temperature stability which leads to much longer life.

Again, I have NO idea of the validity of these statements.

The reason I had the other thread going was that some members on another MB forum were arguing that the MB sluid was just a sham.

John, I have heard the same thing too. I believe this is so because with something so sensitive as paper based friction materials on the clutch disks they need exactly the right coefficient of friction and lubrication properties from the fluid that they were designed for. Wrong fluid and the clutch disks prematurely wear.

I wonder how many more miles it would have gone with the correct fluid. Maybe 250k or more?? But that is just speculation.

Here's another thought:

By traveling 175,000 miles in a 1997MY car, I would assume that lots of the miles are highway, which places a very light load on the transmission (unless towing or steep-steep hills, or towing on steep hills) and since it's not shifting, this would extend it's life. By how much? Who knows, it's not an easy thing to quantify.

However, I have met the occasional super-high-mile owner of 1997 and later cars that have racked up the miles on highways and report no problems with the driveline.

I remember one of the techs on the forum talking about seeing some really high mileage 722.6's with no problems, so they're out there. I think the consensus is that the .6 is very tough and long lived, but must be cared for. It's also best for early builds to have updated bits like ETC's where required, and I'm sure that helps as well.

I will stick to the specified fluid, just in case...

What dealer is rebuilding your trans? I am also in the Chicago area and would like to know what dealer will do it for $2000.

Thanks!