Is the 722.6 transmission prone to leaks? - PeachParts Mercedes-Benz Forum

shertex · #1 10-28-2013, 08:33 AM

Does anyone know if the 722.6 tranny is particularly prone to leaks? I just bought a 98 E300D. Only 73k miles. According to the dealer, the tranny was resealed at 35k miles. Got it up on ramps for the first time this morning....noticed a bit of ATF on the belly pan.

Ordinarily mild ATF leaks don't concern me. But with this sealed for life crap, I guess I now have to buy the measuring stick and breakable tabs for the cap. Oh well.

Other than the tabs and the measuring stick, is changing the fluid and filter and different than on the 722.4?

Zulfiqar · #2 10-28-2013, 01:00 PM

This transmission has two leak points both easily repairable.

1 is the electrical bushing adapter - its the piece where the transmission wiring connects to at the front.

2 is the park pawl thing at the back of the transmission which has a bellows seal on it.

the bushing/plug adapter is very easy to replace as it takes a 7mm socket and only 2.5 nm torque to tighten (very very gentle) you will lose about half a quart or less if you do it.

the rear one requires a full pan drain and removal of the pan too.

Otherwise this transmission is very very good - the way it shifts and handles the torque converter clutch is really amazing for being such an old design.

alabbasi · #3 10-28-2013, 01:33 PM

This transmission should not be treated as a sealed for life unit. You can buy fluid and pan filters and change the fluid. You can also buy a dipstick for it.

ngarover · #4 10-28-2013, 08:59 PM

AH the 722.6.... That transmission has been a bane to me...

I have a very lengthy thread about one in my 1999 E320. And all the issue I had trying to at first rebuild then swap it out. Then after all that I forgot to reseal the front pump on the final replacement and guess whats leaking now...

Do not treat these as sealed for life!@ Not a chance, not unless "life is 100k" IF you do happen to pull it to work on it, make sure you address that front pump seal. Hell just address all of them...

BTW, Orielys caries a version of their trans fluid that is only 2 bucks a quart... save yourself the cash and use it. I've put 15k on the stuff with no issues, except for of course the puddle on my driveway... They can look it up for you easy.

Skid Row Joe · #5 10-28-2013, 11:58 PM

Quote:

Originally Posted by shertex

Does anyone know if the 722.6 tranny is particularly prone to leaks? I just bought a 98 E300D. Only 73k miles. According to the dealer, the tranny was resealed at 35k miles. Got it up on ramps for the first time this morning....noticed a bit of ATF on the belly pan.

Ordinarily mild ATF leaks don't concern me. But with this sealed for life crap, I guess I now have to buy the measuring stick and breakable tabs for the cap. Oh well.

Other than the tabs and the measuring stick, is changing the fluid and filter and different than on the 722.4?

Would you mind taking several pictures for me to see where the leaking is? Please remove the main belly pan for the pictures. The main pan is held in place with (4) screws, easily removed.

I have never had a transmission leak in any of the AT diesel MBs I, or my family has owned up to 400K miles and 20+ years old.

TnBob · #6 10-29-2013, 02:11 PM

nm to inch per sq in

Torque Conversion Chart - Nm to In-Lbs

jay_bob · #7 10-29-2013, 03:50 PM

Quote:

Originally Posted by alabbasi

This transmission should not be treated as a sealed for life unit. You can buy fluid and pan filters and change the fluid. You can also buy a dipstick for it.

And our very own wiki has the procedure...

PeachPartsWiki: 722.6 Transmission Fluid and Filter Change

sokoloff · #8 10-29-2013, 07:13 PM

Your '98 still has the torque converter drain plug, so you can drain about 95% of the ATF by removing both of the drain plugs. I'd change the electrical connector mentioned above on principle while the ATF is drained. It's only about a ten buck part and has been revised numerous times.

pawoSD · #9 10-29-2013, 08:20 PM

My bro's has a 722.6 and it shifts great and is 100% dry at 148k+ and counting. According to service records at some point they did have to replace the wiring seal and the controller (probably got trans fluid in it).

shertex · #10 10-30-2013, 08:30 AM

Prior to my ownership, this car (98 E300D) sat for great lengths of time. On the 722.4 trannys, it is my understanding that, under such prolonged periods of not being driven, the tranny would leak some fluid even if there are no actual leaks....you just top off and drive.

Is this also true of the 722.6?

alabbasi · #11 10-30-2013, 09:15 AM

I can't really tell you, but the smart money would go to the person that checked all fluids before driving the car if it sat for some time. As mentioned dipsticks are available and the fluid should be changed.

Skid Row Joe · #12 10-30-2013, 11:49 PM

Quote:

Originally Posted by shertex

Prior to my ownership, this car (98 E300D) sat for great lengths of time. On the 722.4 trannys, it is my understanding that, under such prolonged periods of not being driven, the tranny would leak some fluid even if there are no actual leaks....you just top off and drive.

Is this also true of the 722.6?

Once you ascertain where the transmission is leaking, then you'll be able to plan which parts to buy. Have you seen where it's leaking from?

shertex · #13 10-31-2013, 10:28 AM

Looks like mine is leaking at that bushing adapter. Good news!

Quote:

Originally Posted by Zulfiqar

This transmission has two leak points both easily repairable.

1 is the electrical bushing adapter - its the piece where the transmission wiring connects to at the front.

2 is the park pawl thing at the back of the transmission which has a bellows seal on it.

the bushing/plug adapter is very easy to replace as it takes a 7mm socket and only 2.5 nm torque to tighten (very very gentle) you will lose about half a quart or less if you do it.

the rear one requires a full pan drain and removal of the pan too.

Otherwise this transmission is very very good - the way it shifts and handles the torque converter clutch is really amazing for being such an old design.