I did a lot of searching, but was unable to find help.

My 1990 300TE w/ 722.358 tranny, 208k miles. The tranny has always been reliable, solid shifting, no signs of slipping at all.
Then, after driving about 50 miles, the tranny started doing some weird hurky jurky while on the freeway doing 70mph. I think it was possibly downshifting to 3rd, then back up to 4th...would go for a short time normal, then did it again...then all of the sudden, I have no tranny. I coast to a stop. Started driving...now I have 1st and 2nd, but no shifting above that.

I have since drained the oil, which was at normal level, did not smell burned, and showed the usual mild particulants you would see.

I am waiting for a new filter, then i will refill the tranny with new fluid and see if this changes anything.

I will not have the filter until Monday.

Ideas? I am totally new to trannies, so any help would be great.

Thanks

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1990 300TE....all comments are about this car...in case I forget in the actual post

A fluid and filter change is more wishful thinking, have a look at the attached apply diagram. Clutch K1 is common to 3rd and 4th so there is some sort of failure either in the clutch , apply piston , or valve body.

Attached Thumbnails

 

One common theme I saw was to go ahead and do a fluid/filter change and see what happens. I guess a low percentage actually corrects the issue.

Didnt expect any miracles

With the pan off right now, I was considering dropping the valve box, but unless the problem was obvious, I would not know what to look for.

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1990 300TE....all comments are about this car...in case I forget in the actual post

I don't have a valve body breakdown handy for this trans, there might be one on the net. ( the 722.4 4 speed is similar just physically smaller, 722.5 is similar as is a 5 speed with a overdrive unit in the tail.)


The 722.3 starts out in 2nd, are you sure you are shifting between 1 and 2 not 2 and 3?

Pressure checks would let you more about what is going on, Line pressure , governor pressure, modulator pressure, not sure if you can watch any friction element pressures on this unit.

Are the shifts you are getting on time and not super late?

If I start out in 2nd, it stays in 2nd. If I start in 1st, it will shift 1st to 2nd, then stay there. I normally do the shifter thing where you lock it into 2nd for longer to get the rpms up before shifting into 3rd. It will not go into 3rd regardless.

The 1st-2nd shift is on time.

I did read about the pressure testing thing...I would need to either buy the tool, or make the tool via the instructions I downloaded...banjo bolt, gage, etc.

Right now, the valve body is sitting on my workbench. I will be giving it a going over this evening. Hopefully, something obvious.

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1990 300TE....all comments are about this car...in case I forget in the actual post

If you can come across a "worm track" diagram for the case, you can air check friction elements by using a rubber tip air gun and ~ 100 PSI air. ( sometimes you need to make a plate that covers an entire track in order to apply air. )

You should hear a solid "thunk" when adding air, you might get a slight hiss. If you can't make any pressure and hear a large air leak, either sealing rings or piston seals have failed.

Might be a problem withe the K1 accumulator in the valve body. You can probably find more info searching for that.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

K1 and K2 are the same, and sold by the dealer.

Here are some meaty threads to help:

K2 spring number for tranny 722.3 - Mercedes-Benz Forum

K1, K2 & B1 accumulator spring kits - Mercedes-Benz Forum

DIY Mercedes 722.3 722.4 722.5 Transmission K1 Piston Spring Repair Kit Install - Mercedes-Benz Forum

K1/K2 does not fix the problem. What i would do short of rebuilding the transmission. Is rebuild the valve body with new seals. mercedes does not sell these seals, but I would buy the $100 dollar tranny rebuild kit from rock-auto(it is by TransTech-American Company) as it contains ALL the seals for the entire transmission, but you are interested in all the little "dime-size" Teflon seals in the kit. One does not need to separate the valve body to expose the "balls" just remove the valve body(and you may not even need to remove the valve body, but just remove one valve at a time, and replace the seals one at a time), replace the large paper gasket(it is in the $100 dollar kit) replace the seals under plate. It worked for me. You can do the whole job in half a day or a day... You will need service literature for reference. I have it if you are interested. I cannot post it as it's too large to post here.

Best of luck,

Martin

Attached Files

MB 722 Tranny Adjustments and Valve Body Diagrams.pdf (436.0 KB, 290 views)

MAVA,
Thanks

I did note this Improvement/Correction suggested by the TT/CT document
(See Attachment)

I wonder if that's from experience outside the MB FSM?

Attached Thumbnails

 

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'84 300SD sold
124.128

I gave the valve body a going over. Everything seemed to slide ok, nothing rough or hanging up. The tension from the springs seemed ok, as far as I could tell. None broken.
Decided to put the valve back in the car with fresh fluid to see if anything changed.
Test drive...car now shifts normal.
I drop the pan. There are now metal flakes at the bottom of the pan, silverish.
When I first dropped the pan, it was more of a fine particulate. Now, more like small shavings.
It is as if I had a back log of metal junk accumulating somewhere, and my messing with stuff loosened it up, and it got purged.
Not sure, but drained it all again, fresh again, shifting fine for now.
Keep you posted...
GREAT LINKS...THANKS!!!

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1990 300TE....all comments are about this car...in case I forget in the actual post

Saint,

Glad you got it going. You must had "junk in the trans"

Compress,

You are welcome

Just buy a new factory B2 piston. The chamfer mod is just to hard to do it safely. The thing to do is to replace the bore seal, and to replace the metal sleeve with the revised plastic sleeve.

How to Replace Your Oil Cooler Lines

Martin

Not to sound argumentative, but if it aint broke, dont fix it?
Why replace the B2 piston?
What I have read gives a list of problems that are B2 related, but none of them are/were mine.
I dropped the valve box again awaiting my new K1 and K2 spring kits. Figure it will all go back in this weekend.
I still have time to order the B2 if needed...just do not understand why I would need it.
Thanks!

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1990 300TE....all comments are about this car...in case I forget in the actual post

Saint,

Yes...No B2 if you do not need it..It is a pain to remove on most cars while the transmission is on the car. It is a mater of a few min when the transmission is out.

Here is rough repair manual for 722.3-722.5, but it has a good troubleshooting and tuning section. Download the master.pdf attachment on post 26

no reverse / jerks in reverse when cold - Mercedes-Benz Forum

Martin

Just downloaded them...thanks!

I also ordered the tranny seal kit like you said...so while I am inside the valve body, I will replace them 23 year old seals.

I am actually looking forward to finishing up this tranny stuff. The hours and hours I have spent reading the myriad of posts...just love DIY!!!

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1990 300TE....all comments are about this car...in case I forget in the actual post

You are welcome,

To do DIY AND... to be informed is a powerful thing!!

The Service manual is here:

Transmision work shop manual - Mercedes-Benz Forum

Best of luck,

Martin