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'84 300D, '78 300CD w/ '82 Turbo, '91 300TE (RIP), '88 260E 5 Spd (RIP), '98 E320 4 Matic (sold)
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Discussion Starter #1 (Edited)
Well,
Because of lack of funds, and a large supply of ambition, I am attempting to rebuild my 722.358. I have been scouring the internet for weeks collecting information. I figured I would share some of what I have discovered for you other insanely ambitious folks.

Step 1: Download and memorize the pdf links below- all 150 pgs of each
http://www.w124-zone.com/downloads/MB%20CD/W124/Index/Resources/27-600trans_removal.pdf
http://www.w124-zone.com/downloads/photos/300TE/remove_tranny/tranny_722_repair.pdf
http://www.w124-zone.com/downloads/photos/300TE/remove_tranny/transmission%20repair.pdf

lots of very nice diagrams, and how to instructions

Step 2: Set up a work area, and make sure it is SUPER clean

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Some tips in the photo above.

Step 3: Find a low miles (<150K) transmission in a junk yard and plan on rebuilding that one, not the 250,000+ mile clunker that has failed in your
W124. It can get expensive quick if you have to replace every little piece due to wear. At that point, it will be cheaper to buy a rebuilt than to do it yourself. If the steel plates are blued, pocked, or worn, don't even bother. Go for a rebuilt transmission. There is nothing left to salvage in your tranny at that point. I picked up one with 140K miles for $132 at my local pick-apart.

Step 4: Don't order anything until you have cracked it open and figured out what you are getting into. Don't order piles of un-necessary parts. I almost sprung for the full "master rebuild" kit, when it turned out that all I needed was an overhaul seals kit, and B3 friction disks. *Clean the S$%# out of the casing before opening anything up. Dirt gets inside and you will need to take every last little piece apart and meticulously clean it. I cleaned the outside casing with mineral spirits on a rag, and steel wool. Then I scrubbed it down with a wire brush and simple green. Plug all holes ( I used pieces of micro-fiber cloth) before cleaning.

Step 5: Clean all of the parts, and place in sealed container full of fresh transmission fluid. Allow to soak overnight, then reassemble using all new gaskets, and plastic, rings etc.

Step 6: Pray to your respective divine entity that you did not miss something.

Step 7: Remove transmission in your car and swap. The exhaust and drive shaft will need to come out. Replace your flex disks and muffler hangers before re-install. Plan on replacing the modulator, speed cable, kick down solenoid, transmission mount, shifter linkages and bushings.

I am using cheap generic walmart brand Dextron III/Merc fluid for soaking the parts. I will also probably do the first fill-up with the cheap fluid and then replace in 1,000 miles with Valvoline MaxLife Dex/merc. I have a feeling the fresh fluid is going to push out a lot of junk and will need replaced in short order.

A few things I noticed when cleaning and beginning the disassembly. The front pump seal was leaking. The kick down solenoid housing was cracked. The modulator was dry rotted and the plastic was slightly disfigured so it was not getting a good tight seal.

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After opening it up, I found all of the B3 friction discs were shot. Completely disintegrated! This was at 140K miles. Pulling the K1 and K2 discs, I could still read the printed numbers on the face of the discs. Essentially zero wear. In fact the only thing in the whole transmission that didn't look brand new to the point that I could still read all of the print was the B3 bands. I am replacing all of the seals because I bought them, and because it would be foolish to not do so, but I could have gotten away with just the B3 bands and a new front pump seal, and front cover gasket. The transmission currently in my car has already lost reverse, and is slipping in several of the gears, so I imagine that one would not be so easy.

Whole project including buying a transmission jack, snap ring pliers, torque wrenches, cleaning supplies, parts, ATF fluid, and junk yard tranny cost $800.

I bought the friction discs, pan magnet, and filter from Makco transmission, best price/ quality combination. Everything else came from authausAZ

Update:
Things I found particularly challenging during the rebuild-
Keep an eye on all the little balls when cleaning out the valve body assembly. There are 18 balls in the 722.3. There is a 19th ball in some of the variations.

Both the transmission I pulled from my car, and the junk yard transmission had a notch stamped into the propeller shaft nut making it super difficult to get free. Here is how I finally got that sucker loose.


What a rebuilt transmission looks like:


Special note:
There are two teflon rings at the front pump housing that are a bugger to get to stay in place. Use vasoline to hold these in position long enough to get the front pump back on without them moving. If they move you will not have a good seal, and there will not be enough pressure to engage the piston against the reverse bands. After all the work to fix the failed B3 reverse bands, you will STILL not have reverse.

*Also don't put the inner LB3 piston seal ring in backwards. You won't have reverse if you do that as well. Durrrrrr

Some specialized tools:



I had to fabricate a spring compressor for the clutch springs. The pressure gauge I got a harbor freight. Modulator pressure should be 2.5 bar at 50kph. The idle pressure is roughly .2 bar lower than driving speed, so you can adjust to 2.3 bar at idle and be fine.




Cheers,
Werner
 

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86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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Go Werner go...Nice write up. Hopefully your entire experience will be moved to the DIY sticky ...keep taking pictures and good luck.
 

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1993 400E
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After opening it up, I found all of the B3 friction discs were shot. Completely disintegrated! This was at 140K miles. Pulling the K1 and K2 discs, I could still read the printed numbers on the face of the discs. Essentially zero wear. In fact the only thing in the whole transmission that didn't look brand new to the point that I could still read all of the print was the B3 bands. I am replacing all of the seals because I bought them, and because it would be foolish to not do so, but I could have gotten away with just the B3 bands and a new front pump seal, and front cover gasket. The transmission currently in my car has already lost reverse, and is slipping in several of the gears, so I imagine that one would not be so easy.



Cheers,
Werner
The B3 friction plate's is a common problem, mine were worn out at 120K

Slow to engage reverse.

 

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About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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Way to go Werner!

I have the cooked box out of my 260E/300E, the unknown box out of a 91 TE 4Matic that came loose with a parts car, and the box in my 91 TE 4Matic project car that won't upshift out of 2nd gear.

That last box is so clean that I'm betting it has been recently overhauled so it should have a lot of good parts inside.

I'll follow this thread with great interest since I see several winter projects developing!
 

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money pits of various forms
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You missed a critical ingredient. Beer!

Nice writeup!
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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You missed a critical ingredient. Beer!

Nice writeup!
+10. Another key ingredient is cleanliness, cleanliness and cleanliness. Wash down any parts before disassembling and/or installing.

The slightest contaminant WILL cause issues. Disposable gloves are a necessity and also consider using a hairnet.
 

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About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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When I briefly considered a beautiful 1999 Audi A8L a few years ago I knew that it shifted kind of funny and I did some research before buying it. I learned that an Audi reman gearbox cost something like $9k, had a 12 month/12k mile warranty (wow) and came in a plastic clamshell container the size of a casket.

I was told that no mere mortal should considering opening one of those transmissions and that they were assembled in a "clean room" to keep out any contaminants. That phrase didn't describe any transmission shop I'd ever been to. LOL
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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Correct on not opening up one of those Audi electronic gearboxes as the trans and diff are combined into one unit and fluid is separated by a diaphragm. If the diaphragm tears, which is not uncommon, huge problems loom ahead.

I too loved those late 90s A8/S8 but having had a love/hate relationship with my '96 A6 C4 chassis Audi I decided to move back to greener/simpler pastures like the W124.

IMO, Germans and electronics just don't mix regardless of marque.

When my W209 gearbox went boobs up just a few miles before the warranty ran out, I was told it would have cost about $12K to fix. That figure covers the radiator replacement (cooler contamination damaged trans), reman trans, GSM (gear selector module) and new diff. My diff blew up at the same time. I was told the diff ring gear is/was made of glass. Yikes

Traded that loser MB in the following day, with my CL500 and C230 shortly afterwards. Glad those electronic nightmares on wheels are gone.

If I ever buy another MB, it'll either be a G class or a Sprinter van with preference towards the Sprinter due to less complexity and being a diesel. Otherwise, it's gonna be a Hyundai Genesis R-spec or Equus.
 

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'84 300D, '78 300CD w/ '82 Turbo, '91 300TE (RIP), '88 260E 5 Spd (RIP), '98 E320 4 Matic (sold)
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Discussion Starter #9
I actually do work in a cleanroom, but I think they rest of the staff would crap a brick if I dragged in a transmission no matter how clean it is.
Cheers,
Werner
 

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'84 300D, '78 300CD w/ '82 Turbo, '91 300TE (RIP), '88 260E 5 Spd (RIP), '98 E320 4 Matic (sold)
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Discussion Starter #11 (Edited)
Also, get yourself one of those harbor freight coupons for the all metal digital calipers ($9.99). Several dimensions need to be taken to evaluate the health of parts. Torque converter placed tranny side down on a table should measure 121.5 mm from flywheel mounting surface to table top. Mine is is 121.7. Not sure what I will do about that. Hoping the one still in the car will be good. $200 for a reman one from makco.

Some day I am going to open a harbor freight store. I love that place.
 

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About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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I can add another transmission rebuild to my list: the one in 88 TE#1 cooked itself on the drive home this evening. It was more or less a repeat of the situation I had a few years ago with my signal red 260E/300E.

I had leaks and fixed them one by one. With the leaks fixed I thought i was good to go and the transmission felt good and shifted fine.

With two kids in the car, heading from my parent's place to my home, I smelled hot oil and looked in the rearview mirror. I was horrified to see a humongous blue smoke screen behind me. The trans was slipping and heating up the fluid enough to boil it out the filler tube onto the exhaust manifolds.

In tonight's version I was only 10 miles from my parent's place so I turned around, turned off the a/c, opened all the windows and the sunroof, and turned the heat to max to remove as much heat from the transmission fluid as I could.

I made it home, thankfully. Short term the MBZ reman trans in recently retired 88 TE#2 (white) will be moved into 88 TE#1 (smoke silver) asap. Joy.
 

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1992 300ce, 3.0, 207,00 mi.
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Sounds like the vac modulator gave out and eng sucked most of the tranny fluid out. Might have a slim chance trans did not destroy itself, don't know if these trans can suffer a catastrophe like you experienced and still recover.
 

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'84 300D, '78 300CD w/ '82 Turbo, '91 300TE (RIP), '88 260E 5 Spd (RIP), '98 E320 4 Matic (sold)
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Discussion Starter #14
augapfel (apple of my eye?), sounds pretty bad. Might be vacuum modulator, or maybe brake band B1 shifted when you pulled the B1 pressure body (perhaps from not applying correct torque to bolt?). If the B1 band was not in the correct position on the drum, it would create a lot of friction which made the heat that boiled off the fluid. Drop the pan and check for shavings. No metal in pan = good.

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Try pulling B1 body again, clean very well with can of parts cleaner, apply new rubber rings, and correct torque. Then replace with fresh Dex/Merc fluid. Maybe you will get lucky.

Cheers,
Werner
 

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'84 300D, '78 300CD w/ '82 Turbo, '91 300TE (RIP), '88 260E 5 Spd (RIP), '98 E320 4 Matic (sold)
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Discussion Starter #15
Updates

I have posted some new photos and updates into the original post highlighting some hick-ups I had during the rebuild. Definitely wish I had know these things going into this.

Cheers,
Werner
 

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1987 300D Turbo Powered by ÜRO
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I have posted some new photos and updates into the original post highlighting some hick-ups I had during the rebuild. Definitely wish I had know these things going into this.

Cheers,
Werner
Glad to see you got back on the horse. Keep us posted and I wish you great success in round 2.
 

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'84 300D, '78 300CD w/ '82 Turbo, '91 300TE (RIP), '88 260E 5 Spd (RIP), '98 E320 4 Matic (sold)
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Discussion Starter #17
Finally got the rebuild running today. Dropped the tranny for the second time, pulled the front cover and opened up the primary pump. Turns out I had put the inner LB3 seal in upside down, and this caused it to tear the lip off. Pressure could not build up behind the piston. Took 7 hours for the removal, front pump rebuild, and reinstallation. Car runs better than I thought possible. Smoothest shifting W124 I have ever driven (considering I have only driven all original 20+ year old cars, this is not saying too much, but it is a good ride none-the-less).

I included some new photos in the original post about the tools I used. I had to fabricate a spring compressor, and I included a photo. Don't give me a hard time about my poor welding skills. I am self taught, and have only welded two or three items in my life.

Cheers,
Werner
 

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Finally got the rebuild running today. Dropped the tranny for the second time, pulled the front cover and opened up the primary pump. Turns out I had put the inner LB3 seal in upside down, and this caused it to tear the lip off. Pressure could not build up behind the piston. Took 7 hours for the removal, front pump rebuild, and reinstallation. Car runs better than I thought possible. Smoothest shifting W124 I have ever driven (considering I have only driven all original 20+ year old cars, this is not saying too much, but it is a good ride none-the-less).

I included some new photos in the original post about the tools I used. I had to fabricate a spring compressor, and I included a photo. Don't give me a hard time about my poor welding skills. I am self taught, and have only welded two or three items in my life.

Cheers,
Werner
Congrats on the success. Many feel automatic transmissions are secret black boxes (me included) I think you're officially a mythbuster
 

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1994 E320 Sedan
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Congrats on the success. Many feel automatic transmissions are secret black boxes (me included) I think you're officially a mythbuster
Seconded. Good for you Werner, that's really great. :thumbsup:
 

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About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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And thirds...

I now have 3 boxes out of the car and ready for experimenting and you have given me hope for a successful outcome.
 
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