When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I bought the car a couple of weeks ago. I am having an issue with the transmission. I’ve read through many situations and articles regarding TCM, solenoids, and maintenance but I am wondering how to move forward.
Synopsis:
In sport mode, it slips going into 2nd gear. I am not sure if to call it slipping. It rev’s up a bit followed by a harsh engagement of 2nd gear. The rest of the gears are smooth. Maybe 4th or 5th has a minor slip/rev to it as well but is barely noticeable. I have an Autel MK808 which didn’t detect any TCM codes. Although, I did clear some old and stored speed sensor codes. I am not sure when the last service was performed. I believe I have the red fluid. I need to further evaluate the service records to see when the last time the transmission fluid was changed.
Questions:
Are these transmissions known for rebuilds with such low mileage?
Is it common for my symptoms to resolve with a fluid change?
I bought the car a couple of weeks ago. I am having an issue with the transmission. I’ve read through many situations and articles regarding TCM, solenoids, and maintenance but I am wondering how to move forward.
Synopsis:
In sport mode, it slips going into 2nd gear. I am not sure if to call it slipping. It rev’s up a bit followed by a harsh engagement of 2nd gear. The rest of the gears are smooth. Maybe 4th or 5th has a minor slip/rev to it as well but is barely noticeable. I have an Autel MK808 which didn’t detect any TCM codes. Although, I did clear some old and stored speed sensor codes. I am not sure when the last service was performed. I believe I have the red fluid. I need to further evaluate the service records to see when the last time the transmission fluid was changed.
Questions:
Are these transmissions known for rebuilds with such low mileage?
Is it common for my symptoms to resolve with a fluid change?
Any suggestions?
Many thanks in advance.
What do your maintenance records show for when the trans fluid was changed? MB calls for 60k mile change interval.
My suggestion is to change the fluid and filter, then observe behavior. Additionally, I would reset the gearbox adaptations.
I x2 this. Unless you can verify that the transmission was already serviced, the fluid and filter need to be changed immediately. If this does not improve shifting, then an adaption is the next step for it to relearn. When I buy a used vehicle with more than 60K miles, I change all the fluids in the vehicle as sort of a health check and piece of mind.
The mechanical side of these transmissions are robust, its the electrics that have issues. The speed sensor fault you mentioned is one of them.
Thank you all for your input. Now that you guys have me thinking, you are right. Even if I find documentation that it was changed, was it really? I've heard and experienced the good ole' fluid change followed by a trashed transmission. Yet, I continue to hear great things - mechanically speaking - from these transmissions.
I looked at my Autel scanner yesterday to see what options I should use post-fluid change. This is what makes sense to me: TCM > Special Function > Tech-in processes > Resetting the adaptation values > Shift. It seems like this would be the option to reset. Anyways, I will order the parts to perform the fluid change tomorrow.
The command "Resetting the adaption values" will erase any learned behavior and reset the transmission to its default settings. If the "adaption of the gearshifts" is anything like whats in Xentry, it will allow you to relearn specific gear upshifts and downshifts.
Out of curiousity, which Autel model are you using?
Hi peeps, I was just out of town so I had to step away from the issue. Thanks again for the feedback.
I am using an Autel Maxicom MK808. Would it make sense to reset the adaptation values prior to changing the fluid to see if that alone may fix the issue? Then reset them again post fluid change?
Hi peeps, I was just out of town so I had to step away from the issue. Thanks again for the feedback.
I am using an Autel Maxicom MK808. Would it make sense to reset the adaptation values prior to changing the fluid to see if that alone may fix the issue? Then reset them again post fluid change?
Might actually be a good idea, not going to hurt anything. If nothing is improved, you can check out the control module and solenoids during the fluid change.
I am having a hard time believing that resetting and changing the fluid alone will fix my issue. I read some old codes with my Autel regarding "implausible wheel speed" or something of that degree.
Obviously, I need to do it either way, but I am thinking further ahead.
Anyways, I'm picturing dropping down the transmission fluid pan - then what scenario:
A - should I replace the fluid and reset tcm
B - should I replace the fluid and reset tcm + clean solenoids
C - should I replace the fluid and reset tcm + replace solenoids
D - should I replace the fluid and reset tcm + send TCM to repair.
Adaptations are performed in real-time with a Xentry console. In other words, one guy drives and a tech sits in the passenger seat with a laptop and performs the adaptation procedure.
The Autel won't change anything. I would just take it to the dealer for this one, let them service the tranny and do a proper adaptation.
I still haven't replaced the fluid. I am running short on time with family visiting for the holidays. The car isn't moving much. I have it charging with an AGM battery charger most of the time.
I believe the autel is capable of adaptations. When you select the option "adaptation of gearshifts" it outlines what seems to be a procedure requiring 2 people. I can show a screenshot tomorrow. I hope this is as effective as the Xentry tool. I am trying to avoid the dealer.
I think I'm having the same issue 2011 E350 Bluetec w 156k...between first and second, feels like the transmission slips / engine revs higher / then slips into second. Really disconcerting while driving. There's a way to reset the adaptable transmission without a computer, I'll paste that below in case anyone is wondering. I tried it...felt like it made a slight difference for a few days but it's back to slipping. Don't know whether to take it to my independent mercedes mechanic or a transmission shop, any advice there would be great. even changing the fluid looks like more of a task than I'd want to handle. Chassis: thanks for this "7Gs are known to lose speed sensors with higher mileage and earlier build years such as yours. New/rebuilt conductor plate is the solution." maybe that's the plan? any idea what this would cost? I think just the fluid change was like $750
Also that reset process, cut and pasted: Turn the key to position 2. You should see all the dash lights come on. Do NOT start the car. Position II: You should hear two clicks and all your dash lights should turn on. Do not start the engine. Press the gas pedal all the way. By pressing the accelerator pedal to the floor, you will activate the kick down switch. Keep the gas pedal pressed all the way to down. Wait. Continue to keep the gas pedal pressed for at least 10 seconds. Turn key to OFF, position 0. Don’t remove the key. Some models may need the key to be removed. Wait 2 minutes. During this process, key is left in the ignition in the OFF position.
Start the car and drive.
Once you perform this procedure the Engine Control Unit (ECU) and Transmission Control Unit (TCU) will work together to learn how you drive by monitoring your driving pattern. After you follow this programing method of the TCU / ECU drive the car for 15 min. Do not race the car, unless that’s how you plan on driving all the time. You should have a transmission that shifts smooth and normal. You may feel like you have a new transmission!
Thanks for the information, Joseph. I will ask the same question they've been asking me: When was the last time the fluid was changed?
On a similar note, I finally got my Autel hooked up and reviewed all the services in memory. I am 108K and the last time the transmission fluid was changed - according to service codes - was @ 38K.
With this confirmation, should I still consider changing the fluid? My gut feeling tells me I should but, my mechanic instincts tell me I shouldn't.
During the last cold front down in south Florida, I noticed the transmission was shifting smoothly. I also spoke with a reputable independent Merc shop in Pompano. They mentioned it's not worth just changing the fluid and with 108K it's better to change the conductor plate and the valve body. My guess is that they want to do the job once. However, that seems like an expensive route.
I'm going to take the car for one more drive and if it's shifting smoothly, I may simply change the fluid/filter.
Yeah I'm guessing if it's already slipping it's too late to change fluid and hope for the best. Did that on my last vehicle and still had to get a new trans. Let me know what they quote you for the throttle body / conductor plate / fluid, I'll post as soon as i get a quote on mine
On the flip side, I've read on the forums and heard from the MB indie shop that the 722.9 tend to have these problems when they sit for a while. It's almost as if the transmission likes to be driven and not stopped most of the time. So, if that is the case and the issue clears on its own from simply driving/resetting tcm, my guess would be that it might make sense to perform the maintenance. The shop I spoke with charges $600
I am baffled at how modern car manufacturers would allow such a long service life for A/T tranny oil, in terms of years and mileage.
I am more baffled if anyone having issues discussed in this thread, to not replace the A/T tranny fluid as first step of action if the oil in his/her tranny has been of service
more than 2-3 years or 30,000 miles.
NOTE : I do 2 years or 20,000KM tranny + oil filter + gasket + bolts + drain plug replacement as cheapest insurance to achieve longest smooth well behaved tranny life
possible as I intend to keep my car if possible for 20 years. So preventive maintenance regime need to be strong.
Mileage wise I am super low mileage per year, since 2020 and today would be 5,000 - 7,000 KM max per year and now at 36,000KM only and 8 years old.
I have replaced my tranny fluid 4 times now, latest one was like 1+ month ago.
My first tranny fluid replacement was a few months after I bought the car used at 9,700KM ish and near 4 years old.
MB dealer did not advice me to replace the tranny fluid YET when I asked but I replaced it anyway at my Indie.
Instantly the speed and sensitivity of gear change respond better to the throttle input.
Example : At 6th or 7th gear at 100KM/H for me to do a 2 to 3 gear down shift to 4th or even 3rd is very easy by throttle ( accelerator pedal ) modulation and in E mode,
it was not the case when the tranny oil was near 4 years old albeit only 10,000KM. To drop gear used to need more accelerator pedal depth and I ended up getting to
full kick-down lowest gear, not comfy.
However all these makes sense, because tranny oil in A/T is totally different to M/T.
A/T tranny is more of a hydraulic system and hydraulic system rule no 1 is ..........fluid cleanliness first and foremost, aside from a good healthy fluid.
Too bad A/T tranny generate lots of heat and all the friction clutches inside the A/T tranny do shed their metallic particles and that is the damn dirt the
2 magnets on the oil pan always catch.
The precision of oil flow control is what makes the tranny function as good as it was designed to do.
Gear change and clutch engagement are all pressure based aka hydraulic.
Watch this cleaning of the valve body, the labyrinth looking thingy.
The poster stated in Indonesian, the tranny issue simply is from dirty oil. valve body cleaned and problem goes away.
See how many small check valves and small orifices the tranny oil must pass thru.
This is an over-sized rebuilt kit for the 3 pressure supply valves which if its bore (liner) at valve body gone bad. https://www.sonnax.com/units/19-722-9
Frequent oil change can reduce oil contamination level causing all these issues.
Sure our tranny has a known maximum service life, but if we can make it operate as smooth/good as it should be all the time.... for as long as possible,
that is the target for a well maintain car. Its like a fortunate healthy man dying in his sleep at ripe old age and not a diabetic , cancer, heart issue plagued since 40 years old and
to die miserable at 50 years old.
=================
This video explains the 3 speed sensor the tranny uses, where one or more can fail.
Imagine if tranny metallic dirt which the oil pan magnets are trying to catch , are also accumulating close to these speed sensors tone wheel, it may create false reading
of an extra tooth. This could trigger Implausible Signal DTC for speed sensors or misreading of actual speed.
I seen similar freak condition on Pine Hollow Auto-Diag or ATS Automotive channel, can't remember which, where there was a metallic debris at the engine flywheel tone ring tooth and
causing wrong pulse count and creating problems.
NAPA also reminds techy of such issue https://knowhow.napaonline.com/commo...sensor-issues/ ....damaged metal parts can create debris in the form of metal filings or shavings, which the magnetic crankshaft position sensor can pick up. The CKP sensor works at a certain distance, accounting for the air gap from the reluctor ring, but captured metal shavings extend the magnetic field, closing the gap and leading to poor signal generation.
Here is a simple logic why I do not want to have oils older than 2 years in my tranny and Mobil Oil would agree. https://www.mobil.com/lubricants/-/m...mendations.pdf “Short” and “Normal” Shelf Life Products Normal Shelf Life:
In general, the recommended shelf life for oils and greases is typically five years when stored properly in the original sealed containers.
A clean brand new oil, not oxidized by 80C or higher temperature, no water vapor in suspension, zero contamination, 5 years storage life.
Now our tranny abused oil, albeit low mileage and if you can believe OE recommendation of say 4 or more years or X miles, LOL.... I guess Mobil Oil is stupid then.
Our mind loves good news, that is natural. So insane tranny oil life both in mileage and years is more acceptable to most..
Does sound less absurd than LIFETIME TRANNY FLUID ... LOL
Up to maximum useable life of a tranny with poor shifting quality yada yada until its demise,
versus tranny in very good working condition for as long as possible up to its end of life are 2 vastly different conditions.
Mechanical wear and tear is more predictable than electronics failure, so we take care of the predictable one first.
The other adaptation is driver driving style.
Its more for how fast or how far lower gear change are executed by the computer based on dude A been driving style.
If dude B been driving granny style and give the car to dude A, dude A need to drive enough cycles with his style to get computer to adapt to dude A liking.
Everytime I went to the track and do enough laps, my tranny need to adapt again in bumper to bumper traffic in the city as its too aggressive for creeping/snail speed.
How long will the tranny hold high RPM before going to higher gear when throttle is not at big opening is also part of driver's adaptation.
No the transmissions are VERY sensitive to the quality of the transmission fluid. I would change it out right away with a fluid. I can help you do this, basically you just need a Slippery Pete hand-pump, the adapter for the pan, and your choice of fluid after you've removed the pan and reinstalled the new bolts, gasket, plug, washer, and overflow tube. You're going to drain about 4-5L of fluid, you're going to fill it, warm the car up to operating temp, and drain the excess. You can sort of do a "flush" by overflowing it .5L at a time and draining it out but this is just a waste of fluid when you can go back in and do another transmission service in six months to a year and keep more of the fluid in thie pan fresh. Even after 20k of driving for the AMG models the fluid usually smells horrendous and there has been degradation of performance almost to the point of the customer asking if their transmission is broken.
Basically because only 2/3 of the fluid gets changed out 95% of the time, the old stuff contaminates the new stuff and degrades the thermal and lubrication properties of the fluid, it being the low viscocity fuel efficient crap we all had to change to, probably IMO makes it worse.
I mitigated this with either annual changes on my customer cars, or switching to a lengthier interval multi-ATF (at your own risk, not approved by MB) like Valvoline MaxLife or Amsoil's FE Signature series which is my running favorite.
One need to drain the torque converter to maximize new oil into tranny. New drain plug can be purchased and has the special sealant on the thread already.
If I remember correctly, TC holds approx 2.5 liters out of the almost 9 liters my 7G-Plus total tranny fluid proper level at 45C.
I need to explain why 20,000KM is my max target mileage. The 2 years is self explanatory.
I been logging my average speed, you can use the Engine Hour feature the instrument cluster has and average speed data is there too.
I log my engine oil for max 5,000 KM or 200 running hours service or 6 to 9 months max now since 2022 , was 1 year max previously.
The average speed city use which is 90% of how the car spend its life at, is 20-21 KM/H.
So the 20,000KM tranny distance, is equal to approx 1,000 hours of tranny oil running life.
1,000 hour is a lot. So my 20,000KM falls under extreme condition.
In reality 10,000KM is 90% chance the car will do in 2 years, so 500 hours tranny oil working life...better.
======================
Oil cools, lubricate and cleans tranny internal.
Cleaning is by holding dirt/contamination in suspension and some will be caught by the filter, some can't be caught by the filter due to limitation
that a super fine filter will do negative impact to oil pump. Since tranny oil filter works at suction side and not pressure side like engine oil filter would, it would be a course one.
MB uses 50 micron (uM) tranny oil filter element
50 micron is not very fine but not bad.
Cummins/Fleetguard aftermarket tranny oil filter commonly is 60 microns as per their catalog.
I believe engine oil filter typically 20-40 micron so I read.
Common rail diesel final fuel filter would be 2-3 microns.
So comes again the question :
Why would one risk having an oil with contamination <50 microns held in suspension for as long as 4-5 years ?
Severe oxidation/degradation aside during the 4-5 years, just simple logic we need to use.
Ever wonder why AMG LSD differential has oil change interval while our open DIFF is deemed as Lifetime Fluid ?
AMG LSD has clutch pack
If clutch pack is not worn out, a slip means the required hydraulic pressure not reached to make clutch get a good bite.
What causes the reduced hydraulic pressure ?
Well ....poor oil flow is most likely . Why poor oil flow ?
Well.... semi clogged solenoids is one best CHEAP possibility.
When I had my W211 the dealership performed a reverse flush on the transmission. This did not involve pulling the pan and draining the fluid that way. As this was not a recommended procedure I insisted that the do it per the book. What do you all think of what they were doing? One thing that occurs to me is that the checkvalves would prevent flowing in certain passages which would mean those wouldn't get cleaned out.
12-08-2022, 10:55 PM
.
