Hi all hope somebody can throw some light on this, from start off the gearbox seems to go through all gears very quickly, when you go to kick down it wont drop back any gears , then on other occasions everything is fine and full power through all gears and kick down is working, somebody says air mass meter? somebody says vacum , somebody says transmission, first 2 i dont know but its a sealed transmission unit which is filled from factory but can it be checked , hope this makes sense as it is killing me
thanks
paul
Year is 2001 and model is ML 270 CDI , Automatic

 

Hi Pauline,

The gearbox has oil in it and the level needs to be correct. Only an MB dealer or somebody with a special tool can check this. Is there any sign of a leak underneath?
The problem could be either transmission or engine related dependent upon how closely you have defined the problem.
The transmission reacts to an engine which is not performing correctly (hence the suggestion of the MAF). If the engine is seriously wrong (from an emmissions standpoint) the trans will go into Limp Home and this inhibits all gear shifting. This situation can clear next time the car is started if the cause is intermittent due to a component which is borderline under self test which is conducted at every startup.
If transmission based then this is a completely different story. MB boxes are usually very reliable even at high mileage but fluid level is of course very important.
To make matters easier to find out what is wrong the power unit is fitted with diagnostics. The codes can be read with any OBD compliant scanner. Some scanners give a lot more information than others though. The resultant codes then indicate possible causes of the problem.

Get the fluid level checked and the codes read and report back with any additional relevant info.
For instance is the CEL Check Engine Light on? Mileage, Service history etc.

Stuart

 

all sorted turned out to be a faulty air mass sensor
cheers
paulie