I have had this car for 1 1/2 year now. During that year the transmission almost daily has given problems.

When cold it switches normally from 2´rd to 3´rd at approx 12-15 miles/hour and from 3´rd to 4´rd at approx 25-30 miles/hour.
However when hot (typically after driving more than an hour) it changes to switch from 2´rd to 3´rd at approx 40 miles/hour and from 3´rd to 4´rd at approx 70 miles/hour. There is in such case no way I can get it in 4´rd at speeds below 70 miles/hour unless it is parked for an hour or so.

Anybody else know about this problem and how is is solved?

 

According to the owners manual for my C Class. The transmission will shift gears at lower speeds in order to warm up the engine faster, for pollution purposes. I have the electronic controlled transmission, so lower shift speeds is normal. But to your point, it shouldn't take a hour for the engine to warm up. I find when the temp needle starts to move then the shifting is " normal" As far as downshifting above 70MPH, are you trying to engage the "passing gear" function, by pressing the accelerator down to the floor? My owners manual states something to the effect the transmission won't downshift if the ems decides the engine will over rev itself. So perhaps it is working the way it should? Also, the electronic tranny is programable and will adjust to the drivers pedel input, are you a consistent driver?

 

Thanks very much for the input.
The shift up to 4´rd gear should according to the owneres manual (and the garage) happen at 25-30 mph no matter what the temperature is. Therefore it is definitly not working as it should. At 70 MPH the engine is running at 3.000 RPM in 3. gear which is far too much.

There is no problem at all in shifting down. Maybe I should try the kick down function ("passing gear" function) more frequently, as I never use it. And yes I believe I am a very consistent driver. I always drive with shifts up at as low speed as (almost) possible.

 

P:erhaps you should give the tranny a bit of a workout now and then, Once in a while I take off and hold the peddle to the floor and let if shift the gears. I read a very interesting article in a bristish mag dedicated to Mercedes cars. The comment was the less you drive these cars the more problems arise, and once in a while a sporty drive won't hurt. I read statements like this with a grain of salt, as too much of anything is not good either. But my 99 C280, has had 3 batteries in the almost 4 years. The reason I am told is I don't drive the cr enough, which is true as I am partially handicapped and driving has become a chore. So perhaps there is some truth to the magazine's comments

 

Maybe your right. I am being blamed by the mechanic that I am not using the breaks hard enough. They are according to him to be used hard sometimes to function properly. Thats even though I am driving 15.000 miles per year.
I will see if it helps to exersice it somewhat harder. It did help with the breaks. Thanks again for the input.

 

Here's what I'd do...

FIND A DIFFERENT MECHANIC. Sounds like he wants you to beat your car so you'll break more stuff and bring him more business.

The trans is supposed to shift at HIGHER RPM (not lower speed) when it's cold. This is to improve overall emissions by lighting the cats faster, not warming up the engine.

The discussion you're having here is "interesting." You two are agreeing that overworking or abusing a damaged or ill-functioning part will fix it. Gimme a break.

 

Obviously I intend not to overwork nor to abuse a damaged part or any other parts. I intend to use the gearbox somewhat more than I normally do. The car was until I bought it not used very much, had only driven few miles compared to its age, so it might be that it just needs to be run a bit harder than "normally". Eg. I never have used the kickdown before only a very few times.

I hardly think it can be expected that I bring more business to anyone here, as its a long way from Denmark to have a car fixed. A new mecanic is fairly expensive here.

I do agree that the trans shift at higher RPM when it´s cold.

 

If you think your car "just needs to be run a bit harder" in order to improve it, then have fun. I do that myself, but not to improve it.

I'm not following what you're saying about changing mechanics. Where's "here" and why would it necessarily be "a long way from Denmark?" You're in Denmark, right? Are there no mechanics in Denmark?

 

Lugnut. I have read your point.
Is there anyone in this forum that have had the same problem as I? or other suggestions rather than just changing mecanics?

 

I'm not aware of anyone with the same problem, but that doesn't mean there aren't any.

I'm not an auto trans expert either. You seem to use mechanics so I suggested changing to one who may know more about MBs and particularly more about transmissions.