Help, I know nothing! Trans Toast?
 

I took my 99 S320 (109,000) in for CA smog and it passed great, with no problems. On the way home the trans began to slip a bit and then it went into limp mode. I got the car towed home. My check engine light is on and the code read P0763.

I took it to a local Mercedes shop and they told me they think the transmission is toast and that I should have been changing the fluid every 40K. I told them I thought it was a lifetime fill. They said no there have been too many problems. They say the dipstick fluid looks black and the only computer codes they are getting are from the trans. ($98.50 diagnosis).

They want to replace the trans with a rebuilt $3700 plus $800 labor. Does this seem reasonable? Should I consider towing for a second opinion? I doubt the car is worth much more than $10K . Just nauseus right now.

Thanks for any knowlegable advice . chris

get another diagnoses first.

george

If they pointed to the black fluid as a sign of a transmission problem it would be time to look for another shop.

cemii -

The code 'P0763' is for 'Shift Solenoid C Electrical'. I'm no tech, but that seems like it could be an electrical part failure in the tranny (solenoid). I would imagine the part is relatively cheap and could be replaced within a few hours. Perhaps add the charge for a new sealant/fluid and maybe you are looking at a few hundred bucks.

Bring it to a shop that KNOWS Mercedes.

Good luck.

Get a second opinion.

Call a local dealer or two and find out who THEY send their trans to for repair and go there.

Here is an old write up from "Gilly" (a respected tech and past moderator) regarding teh 722.6 trans. You do need to change fluids. IMO 60k is prob OK. Use MB fluid for the 722.6, or the newer backward compatible 722.9 (G-Tronic 3353) MB fluid only.

http://www.peachparts.com/shopforum/showpost.php?p=702285&postcount=8

Terry, I am also in the Walnut Creek area. If you have any recommendations on service places, i'd appreciate leads. The place i took it is "German Sport", behind Midas on Autocenter dr. off north main. I need to either get it out of there on monday or authorize the work. Any recom. for second opinion? Stead is my only thought.
I'm very thankful for everyone's input.
chris murphy

Get your car away from there. Many of these transmissions are misdiagnosed because shops have not made the transition from dealing with vacuum controlled to electronically controlled transmissions. If the code says "shift solenoid electrical" then it is pretty certain that it is indeed an electrical and not a mechanical problem. This could be further diagnosed without disassembling anything, provided the shop has the correct diagnostics equipment and is actually willing to use it.

Diagnosing the 722.6 transmission is no big deal. The first step depends on the fault code(s) retrieved. In this case there are two options, depending on the test equipment that's available. The solenoids are located in the valve body and can be activated with SDS. The resistance of each solenoid can also be checked with an ohm-meter from the connector at the control unit. Personally, the first thing I would do, would be to check the ECU to see if it's full of ATF. If the ECU is clean, the solenoids can be tested right from the connector. The resistance values can be found in the Web ETM, available at all MB dealers. Serious indies' who subscribe to Startekinfo also have access to this information. This test only takes a few minutes. Also, at 109K, the pan should be removed to check for signs of internal damage.

I can't overstate how helpful SDS can be in diagnosing 722.6 transmission issues. My advice is to let a dealer check it out. An independant shop equipped with SDS and MB transmission experience would be a good alternative if you're not crazy about the dealer. Good luck

First check the TCM, Transmission Control Module for Tran’s fluid contamination, passenger side rear fender by the fire wall, black box. Look at the wires on the controller (SIEMENS EGS) if you see fluid on the wires that’s your problem.


A while back I posted the complete test For the TCM voltage and resistant test thru the TCM, I did an search and can not find it, maybe you will have better luck than me.

The last thing that happened before the transmission acted up was you had the smog test done. Is that test done on a chassis dynamometer in California? If so, did they disengage the traction control first? I am not sure the car would turn the rear wheels in that situation without disengaging the traction control, but maybe the transmission control unit is confused because the rear wheels were turning and the front wheels were not.

Update: I called AAA for a tow to the dealer. The T/T driver told me he knew a great MBZ only shop a couple blocks away and they would be way cheaper than the dealer. I took it there and they also told me trans was toast ($120 analysis; $5350 estimate on a rebuilt). They, of course badmouthed the last place I took it.

Well, know I'm really confused and feeling really stupid for listening to the T/T driver who may have had a vested interest or not, so I guess I'm going to try a third opinion at the dealer. I'm getting stubborn now and it's the only way I'm going to get an SDS opinion. But then what, I still don't really have faith in either of the two shops I've visited.

Since there are many other small cumulative small shortcomings with the car (tires, rims, 2 rock chipped headlights and a windshield bullet chip, non working auto aerial, window activators weak, etc) I am closing in very quickly on net deducts from FMV that are fast approaching a big zero. It may be time to think about a headstone!

i'll update again after the dealer with whatever the next quantum leap is, just to update for all who have been so very helpful and to reaffirm how lucky you are to know what you're doing.

I also thought it was interesting that neither one of these two MBZ shops would have thought that it might be necessary to turn off the car again in limp mode to get it to engage from R to FWD as I had learned from pure trial and error. Both pushed the vehicle into their shop. But maybe this is unusual and only particular to my problem?

Can anyone lead me to a resource that would tell me which other Mercedes yrs./models used the same 722.6 as my 99 320S. This just so I can look at a potential junkyard swap as an alternate though i recognize the risks inherent.

The 722.6xx started showing in late 97 I believe.

Do mention to the dealer your problems began when the car was on the dyno getting a smog test. THat point seems quite relavent.

My gearbox fluid was as black as diesel oil when I changed it, and that was done at 168,000 miles.

http://homepage.ntlworld.com/tom.jef.../old%20atf.jpg

You have good advice above, before you spend any money, follow it. The gearbox electrical connector is a good place to start, when those seals fail the ATF will wick its way up the cable and into the ECU, making a right mess of things (although it can be cleaned and restored 100% with alcohol or lighter fluid).

Oh, and changing the ATF would be a very good idea. Get yourself a dipstick, and read this:

http://forums.mercedesclub.org.uk/showthread.php?t=25566

follow
 

i did get a code printout and can make a pdf of it attached, but i don't understand

Can you post the transmission adaptation data?

This is all I received from the independent that diagnosed it as unsavable. I do have another page of codes but it only has minor stuff like door contact errors, alarm set offs and the like. This is not a dealer SDS printout. The mechanic also said he detected a noticeable whine from the pump and he said the fill rates were off. chris

Transmission adaptations well show wear tolerances

Off positive or Negative
__________________

If i were starting over from scratch I would have taken this to a dealer first to get the diagnosis and full SDS report.

what i got was 3 indy bottom line opinions, little factual data and all somewhat different but totally confusing to a lay man.

I left the vehicle at the third where i was promised a working vehicle with a 24/24 trans warranty in a week for 4500-5000. they were kind enough to call me in after tearing down the trans to pieces/parts.
Assuming what i saw was all mine, all 3 indy's were correct in their diagnosis of TOAST, however they each got there. The overdrive was completely frozen, many gears and the planetaries were completely chewed up and the valve body was completely jammed with metal chunks. The bottom was full of metal which included several bearings which had fallen out of their races. I am frankly surprised i was able to limp anywhere in the vehicle.

I'm sorry it turned out to be a worst-case scenario, but I'm glad you finally got the right answer.

Every time I hear a story like this though, I'm amazed that any repair shop would condemn the complete transmission without dropping the pan first!!!

Oh yeah, I almost forgot. Make sure they flush the transmission cooler completely. There's sure to be lots of potentially damaging debris in there. Hopefully, they know this, but it wouldn't hurt to remind them. ;)

Iluvmils, I'm confused. You say you're happy to hear that he finally got the RIGHT answer, it seems to me that the first place had the right answer. They told him his trans was no good... It was no good. What better answer was needed? In this case it seems that the customer wanted further convincing, and perhaps the first shop wasn't able to explain to his satisfaction, but they told him what he needed to know. They wern't wrong were they? I think it's just a shame that he had to waste a week and probably several hundred dollars to come to the conclusion that had already been stated.

MV

What he finally got was a sound, properly researched "right" answer. There's plenty of transmission shops that say "rebuild" on every customer that comes in the door and they are right part of the time. But it's like the proverbial blind squirrel finding an acorn - the sinister version.

BTW, how many miles on the car - just curious. The thing that amazes me is that there are people who continue to defend 722.6s. I can get a 722.3 rebuilt for $1250, including in and out of the car. There's a lot less anxiety in the process at $1250, especially when it's likely to last longer.

109250

The first place recommended replacing the transmission based on pulling the dipstick, and seeing nasty-looking fluid. That's a more than reasonable opinion, but before offering to take a few thousand dollars from the owner, they should've dropped the pan, just to make sure. The mess that was found by the third shop would've been all the explanation that was needed.

When the trans is toast, it is way cheaper to swap it out for a rebuilt one from Mercedes than to tear it down. When you tear it down, you are incurring the time and labor cost of tearing down the trans just to see the broken parts.

How much is "way cheaper", i.e. for rebuilt 722.6xx from the dealer?

Well, for starters you are paying the hourly rate $80 per hour for my indy to tear it down. Should he change out the parts and put it all together again, you're paying hourly. He's quoting me $3000 to get a rebuilt trans from Mercedes and installing it with a one year warranty and an extra $1000 with the toque converter. He says that the torque converter typically doesn't go bad so I'm going for the $3000 job. 6 months ago, the trans was missing gears and not shift up from 2nd to 3rd and 4th. He changed the filter and fluid and it didn't improve. Finally the trans went into limp mode 2nd gear so I brought it in to do the trans job. I have a rip-off Penn Warranty that wanted him to tear it down and replace the worn parts but he refused saying that it would cost me more that way. That is Penn Warranty's way of ripping you off because you would then have to pay for the tear down and the diagnosis. Then I read on the internet how Penn Warranty was ripping off people with trans malfunctions by forcing them to pay for the tear down diagnosis and then locating a cheap junk yard trans with no warranty to swap in. So I went with my trusty indy who has been doing my MB work for 6 years and 5 Mercedes,

FINAL CHAPTER:
I got the car back today and must say that it is driving very smoothly right now but...........the final bill was even outside the top end of the estimate at $5098.34 as follows:

removal/ install 782.00
overhaul 1380.00
master kit 742.80
used gear train 885.00 from good core
rblt valvebody 950.00
fluid* 218.52
tax 231.11
misc. 5.06
nice customer dsct (100.00)
TOTAL $5098.34

*The thing that scares me most is that he used Mobil 1 Syn ATF @20.37 a qt and 10 oz. of Lubeguard Platinum and told me they find it better than oem and a big savings to me. Everything I've read in here says NEVER anything but OEM fluid.
and I think the OEM is less.
MERRY CHRISTMAS, chris

Chris, glad the car was fixed! I feel your pain, I'm facing an engine rebuild/swap problem, probably bring me to a similar amount.

Perhaps the techs can weigh in, but when I had my transmission fuild changed in my E430 (Im not buying that 'lifetime' crap), my tech also stated that I should only use the MB tranny fluid. He has no problem recommending other fluid brands for certain models/applications, but he specified for the 722.6 tranny, you use the MB fluid only. The MB fluid is expensive as well.

You may want to look into that...don't want to spend all that money and have a non-spec fluid ruin it.

Just my non-tech $0.02...good luck!

I feel your pain. I just paid $4400 for a MB rebuilt trans with torque converter and control unit. The parts alone from MB was $4000. He only charged me $400 labor as he initially quoted me $4000 but MB gave him the wrong parts cost initially. I paid in cash to save on the tax. My 97 E420 has 132K miles. It quite a shame that these MB trans don't last very long. My indy says that this trans is electronic and that was it cost so much more than the 94 E320 rebuilt trans that he installed for $2400 at 78K miles. My 93 BMW 525iT has the original trans with 168K miles although he had to rpolace the trans oil cooler. With the cost of computer controlled parts no one will be able to afford the new car off warranty. It's a mess and will only get worse.

Did the '97 require the Mercedes fluid only or did that start with the '98 models? BTW, as I recall I think the Mobil 1 synthetic ATF is something like $8/liter. Your mechanic is making one hell of a profit charging you $20/liter. The MB fluid can be had for about $10/liter. If your transmission requires the Mercedes only fluid, then that's what I'd insist be in there.

I notice a couple of red flags with that invoice, no mention of a rebuilt torque converter, they are dirt collectors; a rebuilt is a must especially with planetary failure.


No mention of an updated K2 drum, so he must have used the early design planetary gears which failed often, due to lack of lube, Your transmission failure, early design pre 1999 722.6 transmissions had this type of failure, failure of lube bushing that links the K2 input drum with planetary gears. Updated planetary kit comes with an updated K2 drum.



No mention of a TCM soft wear RE flash, which is done with an updated valve body. Rebuilt Valve body must be the original early design from your car, no updates or improvements.

Hopefully you will get another 109,000 miles from that transmission. .
Good Luck.

Now I get my 97 E420 back with the $4400 rebuilt trans and torque converter and it feels like the trans is a bit rough. It shifts up and down hard and is perceptable whereas the original was very smooth and it would shift seamlessly. Is there a break in period for rebuilt trans? Doesn't MB thoroughly test these rebuilt trans before selling them? My indy says to drive it for a week and bring it in for a check up and not to worry as it is warranteed. Any thoughts?

722.6 transmissions have what is called “Adaptive memory” The TCM will correct and adjust the time and pressure it takes, for a clutch drum to apply to optimize shift feel. The more you drive the better it will shift.

Thanks, Steve. It has been feeling better and smoother as the days go by. I appreciate your input.