Automatic gears failing?

[Pheobian]

Hi, My auto A170 was doing something quite odd today, I was driving along fine for 30 odd mins until I slowed down at a junction and pulled away, the gears started juddering and loosing power, it's as though the thing was in neutral.
Pressing down on the accelerator only sent the revs high but no power in the car.
It seemed to sort itself out after 15/20 seconds but then it happened again a while later. This time I could not get back into gear and I had to stop, turn the engine off and on again and managed to get home. Seemed to only happen whenever I slowed down.

What's going on??

 

[brucemillar]

There are several potential suspects here.

In order of cost:

Check the ATF level > car in neutral > engine hot/running temp > cycle through the gears > dip the ATF.

Selector Module or another electronic fault / electroplate. Get the car plugged into a STAR machine to check for any stored codes/faults.

 

[Benzowner]

Do you have a CTV box? If so, when was the gear box oil changed? Should be done every 40k miles

 

[GLK]

As Geoff said above - most important, plus also do not shift into gear, particularly during colder times, until revs drop below 1000 rpm (when starting the car and the engine is cold that is).

 

[Pheobian]

So, I've had a look and cannot see where the fluid is no a dip stick (apologies for my basic knowledge) where might I find ?

 

[Pheobian]

Do you have a CTV box? If so, when was the gear box oil changed? Should be done every 40k miles

What is a CTV box?

 

[GLK]

There's no ATF dipstick in 722.8 as a factory option, but if I remember correctly it might be possible to add one? I prefer to leave these maters to the professionals.

CVT is Continuously Variable [automatic] Transmission aka AUTOTRONIC - all auto 169s and 245s have this.

You should get the transmission oil and filter changed, unless there is documented evidence it was done at the required intervals prior to your ownership.

 

[Pheobian]

Super! I was thinking the same, best to get it done and fingers X'd it will resolve my problem.

 

[Benzowner]

What is a CTV box?

Constant velocity transmission, I think. I have a B180 which has a CVT box and I am quite sure they were fitted to the A class as well. It's effectively one gear with electronic stepping to simulate gear changes, hence a very smooth gear cgange when driving.

 

[MickyP64]

I had this happen on one occasion with my W169 under acceleration, pulled over switched off/on the ignition and it cured it – never had that particular problem ever again. I believe that the W169 is also fitted with a torque convertor so I assumed it was a problem with that and thought I’d just forget about it until if/or it happened again. However a couple of years later I did need a complete transmission rebuild that included both CVT and torque convertor, which was really quite expensive.

The CVT is ‘factory sealed’ and there is no dipstick fitted to check ATF levels with. I think you could purchase one on line if you wanted one - you’d also have to break the red plastic seal on the filler cap to use it though (you can find this tucked away to the RHS of the engine and you can buy new seals online too).

Personally I think that the CVT is best left to the professionals - take it to a decent indie and get it on STAR diagnostics to see if there are any fault codes stored.

CVT = Continuously Variable Transmission