I purchased my 2006 C280 4Matic in June of 2013 with 95,000kms. For the first 3 months or so I had the car the transmission shifted very smoothly and the only quirk it had was that there was a slight jerk when slowing down and the transmission would go from 2nd into 1st gear, upshifts and kickdowns were very smooth. Eventually, I noticed when I first move off in the morning when I do a rolling stop at a stop sign (we're all guilty of this lol) and go to get back on the gas the transmission would seemingly get confused and sort of hard shift into first and the car will move off. This only happened for the first 2 or so minutes and went away. Then not too long after noticing that problem I noticed when I had to slow down for cars in front of me and then get back on the gas the transmission would hard shift and clunk (you'd hear a physical clunk in the rear) and then keep going fine. It would also jerk and clunk if I floored the gas and let off of it, happened from time to time. It would hold the gear for a bit then clunk into the next gear. If I kind of stayed on the throttle it would smoothly shift into the next gear.

In August 2014, fed up with this I took the car to an independent in the Toronto area that specialized in MB and Porsche and he gave me 2 options. Transmission fluid/filter/gasket change for $420 or a conductor plate replacement for $875. When he plugged in his laptop it showed some codes showing gears 1, 2 and 3 were "implausible or slipping". Stupidly, I opted to have the fluid changed only. He said the fluid was really black but it was all good after he did the change. The transmission shifted smoothly and the times where it would clunk/jerk it was minimal after the fluid change. A few weeks after though all of the above symptoms came back the exact same way. I went back to the shop in November of 2014 and asked to have the conductor plate replaced so he did that for the $875 (I learned my lesson) and changed the fluid, filter and gasket once again with the service. He also changed the connector and seals on the conductor plate as it came in a kit. Now the stinking symptoms are back again. The upshifts are smooth, the kickdowns are smooth but the 2nd to 1st is once again jerky and the transmission clunks when I have to reduce my speed from say 70KPH to 40KPH and get back on the gas. The only way to get around this issue is when I reduce my speed I have to very gently get back on the throttle and it will have the slightest clunk. I thought perhaps it was my driving style so I went as far as borrowing my friends 2011 C250 with the 7 speed for a day and drove it around and guess what? No clunks at any point and that was with 2 more gears to play around with. I drove my Dad's 2010 Acura TL around for a day, no issues here.

At this point the fluid has been replaced twice and the conductor plate. What else could be the cause of the issue? Valve body? Shift adaptations? Physical problem with the gears? Mounts? Flex discs? It's really annoying because if this car didn't have this particular problem it would be perfect. Should I take it to an MB dealer to have them inspect it?

This car now has 120,000 kms and has cost me around $3500 in maintenance and repairs over the last 2 years. $1100 was covered under the 3 month powertrain warranty the car came with which went towards a transfer case service. I don't mind spending money to keep it going but things need to stay fixed especially the transmission! Please advise.

 

The flex disc will be easy to inspect and eliminate as a source of the issue. Its the donut near the rear main. Inspect the rubber for cracks and wear.

This almost sounds like the 2002 trans issues on the C32 cars.

 

I've got the same problem with my 2007 C280...I'm going to follow your post with interest!

 

First, I'm not familiar with 4matic,.... I'm just a mere mortal with the regular 5 speed auto transmission.

You got car used with 95,000km. Did it have previous transmission fluid-filter-gasket changes? It should have partial transmission fluid-filter-gasket change every 60,000km. Since you got 2 transmission fluid-filter-gasket done and are now at 120,000km consider your transmission service up-to-date. Going forward,... do partial transmission fluid-filter-gasket change every 60,000km.

I'm assuming your indy used the correct transmission fluid,... and only did partial transmission fluid-filter-gasket change (only changed the 3L of transmission oil in the pan) as opposed to full transmission fluid change (use 14L to change about 8-8.5L in most of transmission). Even the MB Stealership won't do a full transmission fluid change,... they only do partial.

With older W203 I would strongly suggest checking pilot bushing/ transmission adaptor plug for leaking transmission fluild going through o-ring. Which could then spread transmission oil to your TCU found under the passenger floor board. 2006 *should NOT* have these issues,... but it's a Mercedes - so entertain me and check anyways,... while you're at it spray CRC electronic cleaner on TCU plugs.

Do a "ECU reset",.. it's really a reset of transmission adaptation back to original factory adaptation instead of the granny mode you're likely stuck in due to driving in stop and go Toronto gridlock traffic.

If you're not familiar with any of the above terms,... search!

BTW, you need a real Mercedes-Indy,... I would recommend McNally Auto at 49 Toro Road in the Finch-Keele area of north Toronto.

 

Was the issue regarding those C32 AMGs documented? If I could find info on that it might lead me to a solution. Funny thing I was actually looking at a 2003 C32 AMG when I was looking for a car. I purposely forced myself not to test drive it because I knew I'd get carried away and buy it.

 

I'll check the transmission computer. I remember seeing a DIY somewhere how to get access to it. The mechanic I went to said he had to use extra fluid when doing the change the first time. He said they can't get to the torque converter. The second time he said the fluid was much cleaner so the second change was a help. I commute highway and spend most of my time going 100 to 130. I have a very short bit where I'm on the road in city traffic. I'm one of the few lucky commuters that don't have to deal with traffic

I might eventually have to check out McNally's Auto Service. I went to Workshop MB and I've been there also for front brakes and rear control arm bushings.

I don't know if this was an accident or if they were trying to get more money out of me but when I went to pick up the car after having the conductor plate changed the owner told me the car has a very rough idle and I would be needing spark plugs and a crank position sensor. When I dropped the car off it didn't have any rough idle whatsoever. I told him I'd return to him if anything and paid him for the conductor plate service. Car idled very rough at red lights and the CEL came on while I was driving home. When I plugged in my code reader I got P0170 and P0173 so I did some poking around under the hood and found that the air box wasn't pushed down properly. I figured they needed to move their air box out of the way to access the tranny dipstick. I pushed on it and it clicked down and THAT was the cause of the rough idle. I erased the code and have driven the car about 150kms and the engine is smooth as ever. Again, it could have been an accident but he was really quick in pushing an extra $500 in services when he mentioned the rough idle to me.

 

What's hilarious is that the car always drives beautifully on the test drive. After that the quirks start to show.

 

Your problems sound exactly like my 2006 C280 that I bought back in September of last year.

I did the transmission service and it helped like yours for a bit. Then they did a software update on the transmission. This has at least corrected the problem with the 2-1 issue when doing rolling stops. Basically my car will *not* downshift to 1st unless I come to a complete stop. If I'm even moving just a little when I go back to the accelerator I am in 2nd. This prevents that heavy/jerky feeling when going back to the accelerator in 1st at low speeds. So far I've only had the other "clunk" issue when hitting on the gas a few times where before it happened daily.

I would recommend you have a MB dealer see if you are running the latest software. It definitely changed some of the behavior of my transmission and this was after the dealer always said everything was fine.

 

Sounds like a plan. In addition to that I'll check the transmission computer for fluid in it. I think I'll take off the negative battery lead to make sure. I would do it today but I'm pretty hungover ATM from Friday night I will call a local MB dealership and schedule an appointment. BTW if you don't mind how much did you pay for the update? Is there a diagnostics service I can request for? I think I'm going to use that opportunity to take one of those new C300s for a test drive when I go there.

 

My dealer didn't charge anything for doing the update. I had complained about shifting issues before doing the transmission service, and again after so I guess it was easy/free for them to try next. The techs never actually found anything wrong with it when I would ride with them, or I would drive it was always hard to reproduce issues (of course). Though whenever I dropped it off the last time, when they did the software update, the notes on the service ticket did say the tech experienced rough shifts and that the update was the recommended course of action.

That said I still have some issues here and there that I think aren't normal, but it did seem to resolve the annoyance of downshifting to 1st whenever you're almost stopped but maybe not going quite slow enough to comfortable go down to 1st and I feel like it is more consistent in the way it behaves overall after the update.

 

Saying if you accelerate up to like 30 MPH and let off the gas does your transmission sometimes clunk into the next gear? I get that and hear a physical clunk. I still have to check the computer for fluid. I can't find the DIY I tried last year. I remember getting to the metal bracket below the carpet but I couldn't figure out which bolts to take off in order to remove the transmission computer. Weirdly enough the tranny has been behaving nicely the past few days but I still get that intermittent clunk. When it shifts from 2 to 3 at around 3K RPM it's so seamless and smooth which I think that's how the transmission is supposed to change gears. I wish I could swap a ZF 6 speed auto from a BMW into these MBs, those are fantastic transmissions and they're very smooth too.

 

Alright digging up my own thread here. The transmission pretty much behaved itself since the last time I posted but it started to act up again after a 550KM round trip into cottage country. I tried to check the transmission computer when I got back but like last time I can't figure out how to loosen the metal kick plate to gain access to the computer once I've exposed it so I'll be taking it to the shop that SunnyRayToronto has recommended to have them inspect it either this week or next week. I'll also have them inspect both the engine and tranny mounts. If any work they perform doesn't solve it I'll either have to live with the tranny having the odd clunk, perhaps go with a new transmission or transmission computer or I might just end up trading it for a newer C250/C300 but I'll have to make that decision sooner than later since I want to recoup as much value as I can in this car on trade.

Also, I noticed an issue with the vent position. When I have the AC on I usually have the the temperature set to 22C, vents set to the ones blowing straight at me versus the windshield or floor position and the fan speed at 2, 2.5 or 3 but notice that once in a while the air flow feels like the fan is at 1 or 0.5. To remedy this issue I turn off the system and then turn it back on and turn the fan to 6 and it will all of a sudden blow nice and strong and I can turn the fan back to 2 or 3. When I have the music off (not often) I do hear a sort of clicking or moving action coming from inside the dash. Seems to be a minor annoyance but just wondering what that could be.

 

As I recall, there are M10 nuts at each of the 4 corner of that metal kick plate to hold it down. Use socket set with extension. Once you get those nuts off, wriggle the kick plate to get it off whatever it catches to. With keys OUT of ignition,.... on TCU unplug both plugs and spray CRC Electronic Cleaner on them.

Do an HVAC reset (continuous blinking red light means something is broken) then play around with controls to figure out which HVAC lever is broken - that's likely the source of that clicking sound. Did you upgrade to digital HVAC control unit? It can control more vents and HVAC options than your car has,... so make sure you do HVAC reset,...

 

So I went to McNally's Auto on Sunny Ray's suggestion. Paid $120 for a transmission diagnostics and went for a drive. Of course the transmission was smooth as silk when I took them for a drive. It did the clunk ever so slightly during the drive that the service manager couldn't feel it but since I'm so tuned into the feel I detect it every time. The loud physical clunk from the rear wouldn't happen. They also plugged in their computer and gave me a full report and nothing was found. I requested they check the TCU and he said they found nothing although I doubt they did that because he sort of sidestepped when I asked the question and was done way too quickly. Tranny is still behaving stupid at times and and at other times it's nice and smooth. I think I will take it back to them and leave it for a few days so they can drive it around like they suggested.

They also told me that there's no such thing as reprogramming the tranny and that the "reset" procedure that resets the adaptations that's mentioned here quite often on the forums isn't really a thing. This tranny issue whiles not a bad issue is one of those annoying niggles that really make want to find a solution.

 

Hi, why did you not just buy the c32... the fuel consumption between the c280 and c32 cant be thaaaat much of a difference for you... im just bustin ur chops

 

Haha why stop at the C32? I want the C55 AMG. If I can find a good one I'd be really tempted. I heard one startup and love the deep sound and whine (not sure if it's the power steering or the oil pump).