t1n0

I've searched, but didn't find this particular experience, so here goes.
(Sorry for the repost if you already saw this, but I had posted in the w203/ regular C-Class forum, and I was told I should post in the C32/C55 forum instead, and there's been new 'developments...)
I bought my C32 with 60k miles, CPO, 3 years ago. No problems. I asked on the forum about tranny service, and it was the consensus that fluid should be changed at 90k. (Supposedly, MB trannies are 'sealed for life' but I don't think so...) My mechanic also concurred that it was originally 'sealed for life' but I should change the fluid and filter before 100k. I did that about 9 months ago at about 105k. The tranny was working fine, mind you, but I want to keep the car for as long as possible, so I thought I should change it. Tranny had no issues, ever, before fluid flush. After the fluid and filter change, worked the same, but 3 months later, the problems start.

-->> After the fluid change, it started have these symptoms: Engages and starts good. the shift from 2nd to 3rd is a little soft, but when it does grab, it's kinda jerky; reminds me of someone who doesn't know how to use a clutch. Higher gears are all fine, incl reverse.

Then, one day, about 6 months ago (3 mos after fluid change) the tranny fails. The following symptoms are the same for all three failures: The car will drive a little in first, up to about 2000 RPM, and then it just slips out and revs like neutral. If you stop car, and try to drive again, no drive or reverse. If you put in park, turn off and wait a few minutes, when you put in drive it will engage again for first gear, but slips out over 2000 or so. Once it slips out, will only engage if it's put in park with engine off for a few minutes, but only first gear, and then slips out again.

I took to mechanic, he says it was most likely the solenoid assembly. About $450 P/L. He showed me others in shop as example of what happens. Drop the pan, shows me the part. It's worn, but not worn out, but job is done, and he says it would gone soon enough, and he'll give me credit for the part if I do end up rebuilding, that he estimates will be in the next 30k miles anyway. Ok, drive off, everything good. Lasts about 5 months.

A month ago, Symptoms return: Slips out after 1st, won't drive after the slipout, only engages if it sits for a few minutes with engine off in park. Tow to Mech, He says it's rebuild time. Normally about $1,600, he's gonna credit $400 of recent parts and work as he said he would, so he rebuilds tranny for $1200. Get the car, drives good, all is well. Been driving it for 4 weeks, and I was 'breaking it in gently' bc I want to keep car for a long time.

Yesterday, without warning, Failure symptoms return. It's 5:45 PM, and mech has closed at 5:00 pm until Monday. I happen to coast to a stop at a tranny shop (imagine that) and I tell the guy what's going on. He says that if the rebuild was done and the lines going to the cooler were not thoroughly flushed out, the remains of the previous tranny failure could get back into circulation and eventually cause the filter to clog, in which case it would exhibit the exact symptoms I related to him. He says the filter clogs, pump loses suction, tranny loses hydraulic pressure, and slips out of gear. When it sits in park for a few minutes, the pump can have some fluid return to it, which is just enough for it to engage 1st, but soon again loses suction and slips out.

I bought the filter from him and was considering changing out filter, as mech doesn't open till Monday and I don't want to get a rental, but reconsidered against doing any work on it this weekend bc I don't want mech to say that I tampered with the tranny and void out my 12k/12m warranty. Had it towed home.

1) has anybody had the symptoms I described?
2) Do the prices sound reasonable, bc the dealer wanted 3k for rebuild.
3) Why does it have the same exact symptoms for the 3 failures?
4) Is the second mech at tranny shop correct in saying the cooling lines were not flushed and if so, would driving it a little ways with low pressure/slipping out put excessive wear on what is supposedly a completely rebuilt tranny? In other words, does slipping out bc of low pressure burn up fluid/bands/clutches etc, and this freshly rebuilt tranny now has the equivalent of a year's worth of use on it?
5) This has been my mechanic for this car since I bought it, everything else has been reasonable and very well done, he's always got a full shop of work, and 'been good to me' so to speak, so I don't want to suspect that the tranny wasn't in fact rebuilt, but how in the world does a rebuilt tranny fail after 4 weeks of light use?

BTW, these symptoms have NOT been accompanied by any banging, clunking, grinding, leaking or anything else besides simply slipping out after first, and after ebuild, the mech said that the rest of the tranny was mechanically sound and the pump was good.

Any comments about rebuild experience, fluid changing experience, and the solenoid plate are welcome, and I thank you in advance for taking time to respond,
Tino

====

Update: Mechanic said that one of the clutch plate assemblies that had been put in as part of rebuild were defective from factory and were not engaging evenly and were causing the problem. He said it was very rare to have a new part be defective like that, but it can happen. He dropped and rebuilt the transmission again. It ran fine until last week. it started to go into 3rd gear o the highway. 1st through 3rd shift fine, and it'll go into 4th for about 30 seconds, and then it downshifts into 3rd and won't go up. This equals about 3500 rpm at highway speeds, so the S/C is engaged continuously, you can imagine the gas mileage .

I took it in Tuesday, he said the Tranny control unit had been shorted by fluid creeping up through the harness in to the TCU. He said the electronic parts aren't normally covered with a mechanical rebuild warranty, but he replaced it at no charge bc of my bad experience so far. I went to pick it up on Friday. I asked him if it was thoroughly tested and he said that he took it around the block several times, and had an employee take it up on the highway for a while and everything was fine. I drove off, and it was shifting ok...in the city. When I got on the highway and got up to speed, I'll be damned, it shifted into 3rd again. By then, it was past 5 PM on Friday, so I'm screwed till Monday when they open up again. (Tip: Don't pick up your car from mechanic near closing time on Friday if they are closed Sat/Sun). Had it towed in on Monday.

As a side note: a few times in the last few weeks, the red "Alternator/Battery" alarm went off on the dash, but it was intermittent, so I thought it was just a little wet belt slippage due to wet weather. However, I spoke to Mech today, and he says the alternator is only putting out 11.2 V adn that is most likely the root cause of weird shifting bc Control unit is getting low voltage and therefore erroneous readings from sensors. The diagnostic computer reports no errors codes. I have to get the alternator replaced bc if it does go completely, then my battery (which is still the original battery after 8 years) will drain completely, and they are never the same once they've been drained, and I would have to replace alternator AND battery. Cost of Alternator replacement is $450 ($300 for brand new Bosch unit, and $150 labor).

Hopefully this will be the end of this saga.

Please relate any similar experience of comments on costs or recommendations quoted by my Mech.

Thanks in advance
Tino

francoisisp

your post verry long and not really straight to the point can you sumarize i tried to read but one question who did your tranny fluid change ?

c32AMGOD

I did a full transmission fluid flush on mine and have no issues. Sounds like the alternator could be your issue because these cars are very touchy when it comes to voltages. That being said though, if it is your issue, you essentially did a transmission rebuild for no reason. I wouldn't blame it on the mechanic as there way no way of knowing it was the alternator causing your transmission issues IMO

Trekman

I did tranny fluid and filter change last year, no problem
did your mechanic use the correct fluid?

t1n0

Yes it's a long post, it was a sequence, let me clarify.
Last October:
Transmission fine, but at 105K miles, so it was decided to change fluid, along with the tune up (new plugs and wires, basically). The correct fluid was used, this is a Star Specialist shop, only do Benz's, and the guy is a stickler for OEM/Factory parts only. Won't use any parts I take him if they aren't the exact OEMs, and won't do a 'cheaper' job by using aftermarket. After tranny fluch n fill, it ran great.

4 months later, in Feb of this year:
it went into limp mode. He said it was the solenoid plate giving the error, so it was replaced for $450. When he showed me the part, it wasn't completely gone, which I commented to him. He said it was enough to give trouble, and would go pretty soon, and when I do a rebuild, if I do it with him he would credit the work.

4 months later In June of this year:
the Tranny had trouble and he said it about time for that rebuild. He said he would do a factory spec rebuild, which he does regularly for about $1700, minus the solenoid plate work, comes to $1250. I said OK.

After that, it was great for about 4 weeks, (From July 4 to August 7):
and then had trouble out of nowhere. Had it towed, and he said there was a defective part from factory used in rebuild and the damage was such that he was going to have to rebuild it again, which he did, no charge.

Ran great for 3 weeks. During those three weeks, for the first time, the alternator warning popped up on the dash every few days, but would go away and the transmission worked fine.

Last week:
Alternator warning more often -> tranny downshifts to 3rd on highway.
He took it in and said there were no error codes on computer, but tranny control unit reports there is no 4th or 5th gear solenoids (or something to that effect) despite everything in its place, so he suspected the TCU, and said that hydraulic fluid had crept up through harness and shorted computer. He said it's not technically covered, but will replace the unit for me be cause of the hassle I've been through. He said he tested the car in the city, and the highway, and there were no problems, and no errors on main computer.
I picked it up and as soon as I got on the highway, it went back into 3rd. It went to shop on Monday, where he said the Alternator is only putting out 11.2 V, and that is messing with the TCU's ability to sense and shift properly. So although the Alternator may be responsible for the latest trouble (shifting into 3rd on highway) he will leave in the new TCU, and replace the Alternator with a new Bosch unit for $450 (P&L).

Although it's all about the tranny, it's a long sequence of events, and the Alternator is most likely for the last issue (shifting in to 3rd on highway).

In the end, the work has been done, I'll be getting my car tomorrow or Friday, I'm pretty much committed to going by what my Mech said. I tend to believe him bc he's been working on my car for 4 years, always done great work, he's got a big shop that's always busy, and his predictions and recommendations have always been true. It could be the coincidences of
1) bad part from factory on original rebuild
2) TCU was suspected damaged, but it was actually alternator intermittent low voltage, that wasn't low voltage the day he tested it, thereby indicating damagedTCU
3) now that alternator is continuously low voltage, it's effect on TCU's ability to manage tranny is apparent.

I have to do the alternator replacement, because of imminent failure, which would then drain my battery (which is still factory) and a lead-acid battery is never the same after a full drain -> Alternator AND battery replacement.

On the other hand, this has been the worst transmission rebuild experience in my life (been back to shop 3 times in 2 1/2 months).

So, with all that info I was posting to see if anyone has had a similar experience, if anyone thinks what mechanic has said has merit, about the TCU, the defective part in the kit, and if alternator low voltage can affect the TCU's ability to read input properly and shift accordingly.
I've spoken to a friend who is an engineer although not involved with Benz, and he says that all small control unit computers are usually designed to have their own internal voltage regulators, so that fluctuations in input voltage does not cause the voltage that the control unit sees to deviate from the required 12 V.

And if it all turns out to be true, I'll post a follow up.
T

Trekman

I hope they fix your problem

It would suck if you had to spend more money and car still not 100%

mgiannetto

First let me say that I'm sorry to hear of your problems. I hope the Alternator solves the problems and you have lots of trouble free miles ahead of you.

I would like to thank you for investing the time to write a post in this level of detail. You set everything out, chapter and verse, in a way that all of us can benefit should we experience anything similar. Thanks for doing that.

For what it's worth, $1,600 for a tranny rebuild on a MB sound very reasonable to me.

kent426

So I find this funny that people still believe the myth that fluids can be run for 90K without any ill affects. MB fluid is not special gold, it is synthetic which all manufacturers use. I dumped mine at 40K, it was nasty. Clutch packs deteriorate and plug up filters and sensors. Condensation occurs internally depending on the climate. All these items dilute fluids and cause corrosion.

mgiannetto

Agree. The service manual suggests that the trans fluid an filter should be changed at 40,000 miles (and I assume every 40,000 thereafter).

t1n0

The hassle continues...
Picked it up after the alternator replacement (120 Amp new Bosch unit, $300, plus $150 labor; mech says to avoid the Valero unit, and Valero products in general. My factory unit was a Bosch, and lasted 130K).
Car drove great for 4 days, and suddenly it doesn't go anywhere. I had stopped at a red light, got the green and went to pull off, and the engine just revved. I thought it had slipped into N, but no, it was in drive.
Put in park, back into drive, just revs, no motion (no grinding, banging, etc,) just no forward motion as if in neutral.
Put it in park and turn off for 10 secs, then start, put into drive, and it pulls off like normal...WTF?
Drive slowly to destination without incident (about another mile) and park it for two hours. Time to go home, I start and drive away, all good. about 3 miles later, goes into second and won't come out, "check engine" light comes on ( so I pulled over and looked under the hood, the engine was still there... j/k...disregard...)
Anyway, check engine light is actually agood thing in this situation bc it means the error code has been stored. Limp on home, park, towed to mech next morn.

[About Limp mode: there are two, a mechanical, which may reset itself after you turn car off for a while, and the electrical (with error code) that will not let go until it has the error code cleared by diagnostic computer]

I followed tow truck to mech, bc this is the 5th failure in 4 months (4th after rebuild) and although I tend to "let professionals do their jobs" I cannot afford to be without my car anymore, this has to have an ending already.
Error codes were indicating bad electrical signals/levels. (previous post I explained the previous repair which was to replace Alternator, which it was stipulated that the low voltages were confusing TCU. It was a long shot, but I needed the Alternator anyway.) I inspected the harness and connections with mech, all seemed good. We cleaned al contacts, and reseated the harness. Take the car off the lift, and now it won't even move. After much discussion, he dropped the tranny out again and started a complete inspection. (This is the third time he has to drop tranny). It's decided to replace the valve body with a used unit. He calls to have me pick up car next day, and tells me it has a "slight bump going into second"...yeah, right, the ****** chirps the rear wheels and snaps your neck back from 1st to second. As if was once again Friday, and I need my car, he told me to keep it for a few days and see if the bump smooths out, and if it doesn't and I want to bring it in, to bring it in when I can leave it for 3 days so they can drop it again and do a slow and thorough inspection. I took it and have been driving it fairly aggressively ( I've been driving it easy the last 4 months ever since it had the rebuild bc I wanted to break it in gently, and I had forgotten how much fun my car is). Any way, the bump has smoothed a bit, but it's still noticeable. If it smooths out completely, I'll have to decide whether it'll be time to call it 'good enough' or take it back and get the valve body replaced with another one (he kept mine at the shop). BTW, a new valve body would be $1,100, but he said he would cover the labor as part of the warranty, and I'm sure he would be happy to in order to put this nightmare behind him.
Be sides being a bit uncomfortable, my concern with the second gear bump is the stress it would put on other parts, from the motor mounts, to the thrust bearing, but mech said it wouldn't do any harm, only to the tranny if persistent, and he'll cover it anyway.

Since replacing the valve body has 'worked', it appears the catastrophic failure after the rebuild due to the defective factory replacement part managed to get some particulate past the filter and into the valve body, which is a highly precise hydraulic mechanism; any scoring or damage to the interior of the cylinders or passages in the valve body would cause leakages, and however slight, that represents fluctuations in the pressures that regulate the logic of the unit.

I'm going to keep it like this for a while, as much by choice as by necessity bc I've been without my car for 5 weeks out of the last 4 months, and see if some spirited driving doesn't loosen it up a bit. All other shifts are perfect, and the b1tch is super tight; the RPM never 'moves' from the speed of car when I accelerate or take my foot off the gas...it's locked in like a manual gearbox...I like that.

If anyone knows about used valve bodies vs new ones, break-ins, etc, please comment.

PS: About the fluid change....yes, MB dropped the ball on that policy. When my car came out, in 2003, the transmission was supposed to be 'sealed for life'; it has no drain, and no dipstick. A few years ago, they revised their policy, saying it should be changed at 90K, and just recently I believe they have revised it again, to every 60K, but don't quote me on that. Check with a certified MB mech for their current policy. Had the policy been then what it is now, I would have flushed it sooner. I got my car at 60K, as a Certified Pre-owned, and at the time, it was still the original fluid bc that was the policy.

I have tried to be a thorough as possible so someone else may benefit from my experience, and I will follow up as necessary.

loudandheard

If I remember correctly, valve bodies are not that expensive. I remember some one posting a part number for larger valve bodies and it was a couple of hundred dollars. I'll see if I can find the part numbers.

I understand your pain, I've been dealing with trans fluid leaks and it would happen at the most inopportune times. Good luck.

t1n0

Well, I didn't bother posting all the other failures/returns to shop, but it continued a few more times, until in November, he said he'd had it (imagine that) and returned my money, and said "you'll have to go elsewhere. After 8 failures, he finally gave up.
I took it to a MB tranny only shop. He figured it out real quick, as soon as he disconnected the hydraulic lines from the radiator and a few inches of water came out. Wouldn't you know it? The god forsaken coolant contamination! And I TOLD mechanic #1 about the Valero/glycol contamination recall, and asked him several times during the course of this nightmare if he had checked tranny fluid for glycol, he said it was fine. ******' Aye! Can you believe that ****??

Tranny specialist (mech #2) dropped it out and showed me my tranny guts, and the mild corrosion on the solenoids, and said, "there's no way they (Mech #1) opened this tranny up recently and didn't spot the corrosion on the solenoids, that's an obvious indicator"...
They (mech team #1) were, however, fixated on the valve body, and in opening up the tranny and removing the valve body, in the process they would dump about half the fluid, thereby 'rejuvenating' it a bit, and then whatever they tried, 'voila, it's fixed'...yeah, right, but not bc of what you did....it 'works' now bc you've dumped some contaminated fluid out, dingo, and a short lived fix at that...sometimes just a few hours...long enough for you to close at 5 PM on Friday and leave me without a car for another few goddamn days.

So, although I avoided getting a '02 bc of the dreaded gycol contamination issue, there wer some '03's (like mine) that also have that risk bc of Valero radiator. I believe I read on this forum that the Valero unit was used as late as September '03 (my car is a model year '03, but was built in 12/02).

Well in the end, all of those failures and contamination rendered the rebuilds useless...the water content in the tranny was such that the clutch packs had disintegrated, bearings and electrical contacts were corroded, bearings had disintegrated...Mech #2 showed me a needle bearing pack that actually only had 6 out 32 (i think he said) needles left....in short, my tranny was fukked...."proper fukked".

Mech #2 made a project out of it: replaced everything that was corroded, above and beyond a new rebuild, replaced bearings, and swapped out my torque converter and replaced it with a new unit from the E55 model tranny (...I told him I like to drive 'spirited'.. ) and that torque converter is rated at over 500 ft-lbs, so my 330 ft-lbs max engine should never wear that ***** out

Now....What to do about the Valero radiator. Mech #2 said to replace the radiator, but I said.."not so fast" I didn't want to spend a couple of hundred dollars on a new radiator to replace one that otherwise works (cooling the engine) and still return to the design of having my tranny fluid circulate through my radiator. After the last 8 months of this disaster, I just don't like the idea of oil and water ever being in the same radiator ever again in my car....ever....again...SO we decided to keep the Valero unit, plug the hydraulic in/out holes, and install a separate tranny cooler, like what trucks get as part of a 'tow package'...as a matter of fact, we put in the tranny cooler from a Supercharged Range Rover...the only trouble was where to put it: there's already 5 radiator/coolers in front of my engine. There's two coils for the engine radiator, an A/C condenser, an engine oil cooler, and a power steering cooler...that last fact really pissed me off, bc I though to myself, "AMG put in a cooler for the power steering, but somehow didn't feel the need to have a separate cooler for the transmission???" How do you design a car with a supercharged, torque-happy engine, and somehow rationalize cooling it through the engine radiator like most common cars??...Fock!
Anyway, he managed to fit that Range Rover cooler in so neatly, right behind the PS cooler, it looks like a factory job. (I'll post some pics if anybody wants to see). He did a really t1ts job. And the beauty of the Range Rover cooler is that it has fins designed just thin enough to restrict flow when its cold (viscous) to reduce the circulation, and thereby reducing the cooling effect, so that a cold weather (< 35F) bypass is not necessary...when the weather is too cold, the fluid gets cold, and the circulation decreases, until it finds a nice balance...self regulating...pretty cool design on Range Rover's part. I've been monitoring it this weekend with the scanner in real time, and in traffic, with firm accelerations, my tranny fluid is between 90 to 98 C...perfect.

The one thing he didn't replace (probably bc I told him I had put a new one in) was the conductor plate. ( coulda/shoulda/woulda...) After 2 months of great driving (Jan-Feb) the b1tch went into limp mode last week...fault code was the speed sensor reading. We cleared the code and it drove great for another week and did it again, so we replaced the the solenoid conductor plate this week.

I participated in this last process: When we took the valve body down, there was some particulate matter about, nothing major, but visible nonetheless, and it had also gathered around the speed sensors on the solenoid conductor plate(looked like magnetic 'hairs' you see when you put metal filings around a magnet) The sensors work by magnetically sensing the rotating metal parts in the torque converter assembly so that extra material that was gather around the sensor effectively rendered the sensors 'blind' so,..-> faulty speed reading sent to computer -> limp mode.

We rinsed and cleaned off valve body, blew dry, and replaced the solenoid plate, and replaced about 5 qts of fluid (Mobil 1 synthetic, btw, not the MB stuff) and it worked. However, the reason there was particulate about teh system was bc he had also done another experimental 'mod' to my unit: he drilled a filter bypass hole (4mm) in the filter stem and put a screen mesh in there, bc he says the flow isn't enough through the filter, and this bypass hole will increase flow. Unfortunately , that mesh doesn't trap the very small particulate like the cloth-fiber filter does, and there was still 5 other quarts of fluid in left in there after plate replacement, so whaddya know?.... It did it again this morning. Luckily he had given me a scanner to use for the weekend, so I cleared the error (Speed sensor error code) without a problem. Since, it's been another 50 miles ok. I told him we have to put in an intact, unmodified filter to catch the particulate or this will continue, and he agreed....his filter mod design is a scrub.

The effect of that E55 torque converter is that it drives a bit like a GM Hydra-matic now...if I leave it in "D", the RPM's go to 2500-ish and the car accelerates through gears with the RPM's only rising a little in between shifts (and smooth shifts at that); very much like a GMC pickup truck does; if you've ever driven one, you know what I mean.... the torque converter is , well...converting torque However, if I accelerate firmer, it starts to grab firmer, and if I start doing sports shifts, the RPM/speed relationship is more direct/linear, like a manual...If I put it back in "D" and start driving chill again...it goes back "Hydra-matic" mode....I like it.

Well, I hope I have explained everything well enough for someone to gain some insight if they have similar situation, or even similar to small parts of my overall experience. It has been a friggin nightmare for me, but I like how it runs now.
I'm fairly certain that the 'intact' filter we'll install on Monday and another 5 qts of clean fluid will resolve issue of the break-in particulate matter gathering on and thereby blinding the speed sensor.

Onward and upward...

(Speed Sensor 3, "Y3/6n3" and error P2203, btw)

mikekuriger

I actually never had any tranny issues until I started changing the fluid. I've had the fluid changed twice now, and both times caused the tranny to "slip" more. Right now, it's almost like driving around with the clutch half out. And when the torque converter locks up it's got a definite "jerk"

So I for one can say without a doubt that changing the fluid has had a negative impact on the transmission. I'm not sure if there is an additive that is missing in the new fluid, or if there are air pockets in there causing slippage. All I know is I believe I need a full rebuild now to get it back to normal.

mgiannetto

That is concerning - so do we change the fluid (and run the risks you identify) or leave it alone (and run the risk inherent in that). Hum, what to do......

tw2

^ my thoughts exactly. As I said in one of the other threads, you either leave the original fluid and wait for eventual failure or change it and risk immediate failure anyway (yes it is probably a very small risk but there are plenty of examples on the forums). Both require a rebuild. Neglect is certainly a whole lot easier and for a transmission with nothing wrong with it, it may drive like normal for many more 10's of thousands of miles.

I still haven't made up my mind as to whether I do nothing or just change the filter, magnet and fluid in the transmission only. I would never consider a full flush after reading the many failure threads after this.

Autotechnica

I'm having a similar experience. I changed the fluid last year at 100,000KMs because I had the common "tranny jerk" which I'm convinced all C32's have due to lock up. Afterwards, I noticed at low revs the tranny does slip as acceleration at moderate throttle was not smooth. The lock up engagement is also a lot rougher. It's a swift kick in the back. It feels like a heavily modified race transmission. The AMG autoboxes were designed to take more power, so I wouldn't expect it to be super smooth. However, it was smoother before the fluid change. Once lock up engages I don't have any slipping issues. The slippage is more apparent when the motor/tranny is cold. It's not a big problem for me. When the car is warmed up the slippage is barely noticeable. Mainly it just makes the car uncomfortable to drive at low speeds/revs.

Bry

JonMBZ

That is the problem with taking your car to "specialists" "MB only Star only" (who mostly used china pirated cloned systems) etc most of these shops NEVER use MB ATF I should know im a wholesale parts advisor and they buy the maintenance parts minus the fluid. You always have to be skeptical a lot of these indie guys. Some of them have been fired from dealers and started their own ventures or joined other smaller shops where their reputation doesn't matter (cheap labor as well). I have had guys working on MBs for 30+ years still doing shady work that don't know what their doing they also don't have updated training or access to new TSBs or MB bulletins or systems that help them follow correct procedures. The dealer is more expensive the but work is backed up and closely monitored and logged. The fact that he didn't check for glycol contamination, the most common problem in these cars especially after seeing the TCU wet is a big red flag. MB now says trans fluid should be changed at 60k on all their cars as well.

mgiannetto

Jon, do you know if this guidance supersedes what is in the maintenance book - which for my C55 indicates the trans fluid should be changed every 40,000 miles?

Quicktwinturbo

It's always better to change ANY KIND of fluids often as possible. I usually change oils every 5000, even though the manual recommends 10,000.

mgiannetto

I generally agree - and do exactly the same as you for oil changes. Theissues others are having when changing the trans fluid is giving me some pause. If MB has changed the service interval for the trans fluid it would be good to know that.

JonMBZ

MG I was just going by the last interval I was told by a service rep, not by the book. If it currently says 40k, which I personally never heard of then go by it. Also make sure you are checking the correct transmission type 722.6 because I only know of the 722.9 being at a 40k interval. I understand you wouldn't want to do it early because it's an expensive service. One that I still have not done because of the costs. I plan to flush the system completely when I do it. Either by removing the torque converter and draining it then running an extra 5 quarts through the system to push the old fluid out or by removing the hose and have it pump it all out on its own. while refilling it. The total capacity is 11 quarts IIRC of the top of my head so that will be around 16 total at 19.50 each plus the filter and gasket and service costs.

mgiannetto

Thanks Jon. The maintenance booklet for my '06 C55 indicates the trans oil and filter is to be replaced at 40,000 miles. The footnote says its not time dependent, so I guess it does not matter how long or short it takes to get there - just do it at 40,000 miles.

What is interesting is the maintenance booklet never indictes that it should be redone - and this extends as far out as 150,000 miles. So it seems to be a one time deal. Sounds odd to me.

The maintenance booklet covers not only the C- AMG, but also the CLK, CL, S and SL AMG models (each has it's own section in the booklet) and in every case the trans service is indicated to be done at 40,000 miles - and never shows as being required again. Again, this seems odd to me.

tw2

My local dealer said it would have been done at around 60,000km (about 40,000 miles) and never again after that. Maybe it is due to the transmission being newer?