Having only had a c270cdi for just over a week and asking a stupid question last week here goes with another one: as someone who is 'green' to automatic gearboxes something unusual happened today. i was coming out of town into the 60mph zone so i floored the throttle to 'kick down'. The engine revs went up and the car pulled very well for a few seconds as it changed to a lower gear when suddenly it seemed to go into neutral. the display still said 'D' and the gear lever was in d but the box was certainly in neutral. I stopped the car and shifted the lever to N then 'R' then back to drive and it was all ok then. was i just being too wicked with the accelerator wide open or could it be more serious?
the engine revved up but not as far as the limiter because i eased off having realised the drive to the wheels was lost.as i coasted along to a standstill the engine could be revved freely, i didnt want to move the gear lever until i had stopped the display showed 'D'. the car drove normally after I got it back into gear
I don't know whether the display light is fed from a switch on the gearstick or indeed from inside the box, but unless this happens again i'm inclined to think that you may have just had the gear selector not fully engaged and when you booted the car it slipped into neutral again.
If it happens again you would do well to post on one of the two MB forums..some clever chaps lurk there including full time MB mech's and indies.
The first thing I would be inclined to do is to check the fluid level.
The problem with this suggestion is that there probably isn't a dipstick on this gearbox, so, you may either have to take to to an independant MB specialist to have them check it, or to obtain a dipstick from a well known auction site.
Although some might suggest it, I wouldn't be tempted to make up a dipstick from curtain wire - the MB service dipstick has a stop on it which the curtain wire bodged ones don't replicate properly.
I've got the same model of car & have seen some horrendous stories about autoboxes (and other things) of this vintage.
You can be sure it's something as simple as the 'box just 'protecting' itself in some way from too fierce usgae or something well serious. It could be symptom of imminent demise; after all, it either 'decided' to disengage for health reasons, or something's breaking.
I don't want to be too pessimistic, but after c-class ownership of a few years you develop a certain sang-froid & fatalistic attitude.
See my two pennyworth on the Blue Efficency thread. Last gearbox hassle I knew of was a family friends E320 CDI. It used to really thump into second gear with a hell of a bang and then packed up. He was lucky with the box (software re-programmed) but the turbo went a month later. I'm talking about the later V6 engined car here.
it has 'w' and 's' winter and standard as far as i know it hasnt been moved to 'w'. just a pity i listened to a few people who said the mercedes auto box was the one to have! Surely if the oil level was low a fault would have been indicated/there would be signs of an oil leak and or the gearstick wouldnt be as smooth as it is? Have drove 50 miles since this and all is well could the gearoil temperature been a cause if it wasnt up to temp?i have a few months warranty on the car so if it is something serious it will show itself soon hopefully.
>>Surely if the oil level was low a fault would have been indicated
Don't call me Shirley :-)
There's no gearbox oil level sensor
>>there would be signs of an oil leak
Possibly, or it could be that the gearbox hadn't been filled properly
>>and or the gearstick wouldnt be as smooth as it is?
If you mean the gearchange is smooth - that's mainly because of the way the electronics works, and the gearbox and engine "talk" to each other to smooth the shift.
>>well could the gearoil temperature been a cause if it wasnt up to temp?
Not as such, but, the oil level does rise significantly when hot - automatic gearbox dipsticks have different markings for hot and cold levels.
I suggest checking the oil, because it's absolutely and always the very first thing to do with any automatic gearbox which relies on hydraulics to work properly. Not checking the oil and beginning to look at more complex things in the system would be equivalent to re-wiring your house instead of chaning the blown lamp bulb.
If it's pre-2004 then it's worth checking the radiator as the ATF cooler is built into the radiator and then can cross-contaminate. Look on the MB forums for "valeo" (that's the make of the dodgy radiator). Some owners think it's worth changing to the newer radiator, or even fitting a separate ATF cooler, as a precaution.
You could get the ATF changed at the same time as MB has changed their mind a couple of times about whether these boxes really are sealed for life.
If this is the 722.6 gearbox (check the build sheet for your car, or, put the VIN into www.detali.ru/cat/oem_mb.asp to check), the original MB spec was to say the gearbox was sealed for life, and the oil didn't need to be changed. This view has been revised, and I understand that MB dealers are now changing the oil at 60k intervals. It is important that the correct oil to Mb's spec is used, and the easiest way to ensure that is to buy the oil from MB, or get MB to perform the change on your behalf.
There were also some of these gearboxes where oil seeped through the bushing in the connector at the gearbox end, and wicked its way up the wiring loom, eventually flooding the gearbox ECU - it will be worth asking to make sure your gearbox is or is not in the affected range of production. Replacing the connector bush is a quick job which can best be done during a gearbox oil change.
>>I understand that MB dealers are now changing the oil at 60k
They did retrospectively add a one-off change at 37,500 miles (60Kms) to the service schedule for cars from late 2004 onwards, but they seem to have dropped that again now.
It's also not possible to drain the torque convertor on cars after a certain date so the MB dealers allegedly use a power flush thing.
Despite what MB say, it is considered a good idea to get the fluid changed regularly, either at a dealer of a good MB specialist. Including dropping the pan and cleaning the filter, the job seems to cost around £200 wherever it gets done.
>>It's also not possible to drain the torque convertor on cars after a certain date
Yes, it's a backwards step; however, many makes of car never had them! There's more oil in the torque convertor than there is in the sump, so, you do need to get it out to have carried out an oil change properly*. One way to deal with this is to temporarily remove the oil pipe going to the cooler, and add some flexible pipe to point it into a catch tank, and then crank the engine over to pump more of the oil out.
* Unlike engine oil, where there's much more in the sump than there is anywhere else in the system, even if there is an engine oil cooler.
sorry i meant the best type of engine oil to use for the engine
In practice it'll take just about anything, but if you want to be pedantic then use a fully synth oil that is MB229.3 or 229.5 approved. Mobil 1 from Costco is pretty good at £23 for 4L (you'll need 6.5L). They do a turbo diesel version for the same price but allegedly it's the same oil in different can.
an update to this thread nearly 4 months on!went back to the dealer and he took it to a specialist for fault download.Came up with a transmission fault think it was P2500. It was then taken to MB dealer who found the same fault code.They checked oil level ok, and reset the transmission ratios as they were were "implausible" i think was the word used on the printout i was shown at said dealer.Is this a load of cobblers? sounded like it to me, got about 15miles down the road when engine was fully warmed the same fault would appear, ie when the throttle was floored at about 40mph 2200rpm the car lost drive. Next thing the dealer had done was an "electronic plate" on the gearbox was changed not sure what this is but seemed to make a difference for a week or so then the fault reared its ugly head again!car is fine to drive normally just if you hit kickdown at this speed and rpm it will lose drive. strangely the last few times it has happened as i coasted along the engine will go back into gear again after a few hundred yards! never had an auto box before because of the possible problems and expense. bo-peep?
I think you have a potentially serious problem with the transmission. The control module is detecting that the input and output shaft speeds are implausible and throwing the box into neutral to protect it. This is most likely due to slippage in the transmission. Which could be due to wear or some other problem (low line pressure).
I would get the transmission looked at by an AT specialist ASAP and not drive it too much.
I think the "Y speed sensors" , whatever those are, needed cleaning
BTW I sold my CLK and got a proper sports car, well not really, a rather classic Jag XJS, and I have to say it was the auto box more than anything that robbed the CLK of any driving enjoyment. My XJS is a manual
My wife might get a C Class estate this year, and we have both agreed ,.... look for a manual gearbox come the time,
The only really good autoboxes I have driven have been in Nissan 200 SX and Honda Accord V6 coupes, both Japanese. Actually two others, Ford Scorpio Ultima yonks back had a fantastic auto box, and the VW Bora 1.9 TDi Tiptronic ( as opposed to multi tronic or DSG) was also very good.
but many others have been dreadful if you like a sporty drive, the Merc included.
They did manuals with foot operated parking brakes. If they still do then I'd not want a manual version ;-)
Edit: Just realised it sounds like they didn't do manuals. They did... with foot operated parking brakes. Which my response was against... surely you wouldn't want a manual with a foot operated parking brake with a manual hand release.
Thinking about it i've driven dozens of MB's and apart from vans i've never driven a manual.
Because they almost always get sold as an auto. And with the old foot operated parking brake they didn't want you to opt for manuals. Electronics may help now though but hill starts were not easy I guess with a foot operated parking break.
I've driven C- and E-Class Mercs with manual transmissions and had no problem with hill starts. The only problem is, when stopping, you have to put the gearbox into neutral in order to take your left foot off the clutch to apply the brake. To pull away you put the car in gear, find the biting point on the clutch, then release the parking brake with your hand. The latest C- and E-Class definitely still have this type of foot on/ hand off type of parking brake, don't know about the S-Class, I haven't driven one!
I still wouldn't buy a Merc with a manual transmission because I think Mercs are much nicer to drive with automatics.
Paul ,in regard to another of your posts regarding a MB auto gearbox that went into neutral when you kicked down , I have had the excact same problem and it started about 3 years ago , they changed some electronic part in the box but it did the same thing however after that I lost my sight for 1 yr but for the last 2 years it has driven ok untill you kick down , as my wife now drives it it has only done this a few times , I was wondering if you ever got to the bottom of the problem .