2002 plate C 240 Est Auto Gearbox Gremlin

[shaneslk230]

Can anyone enlighten me on why / probable cause for my gearbox to suddenly run out of forward & reverse drive ?
The car has no leaks, it had filter and oil change just a 2 years ago , it's also had a brand new Gearshifter a year ago this Aug.
The car will drive until it seems that the oil gets hot, then it's a wait until cooler, I haven't yet had a full Merc Star Diagnostic run out.
When the breakdown initially happened on the Isle Of Sheppey there was a notable ' Whirring sound ' while pulling away, that then led to loss of drive power and a call to the RAC.

 

[Petrol Pete]

How many miles on it ? Could the T/C be failing when the ATF gets hot or the lock up clutch slipping under load.

I think you will need to get it 'plugged in' I know MB IcarSoft 2 can monitor lock up clutch operation while driving.

2002 C class ,? I'm guessing it's a 722.6 transmission.

 

[shaneslk230]

Thanks Petrol Pete,
Yeah, I thinks thats the first IA , and go from there. There's a company in Epsom ( DDR ) that specializes in MB Gearbox's , it's getting the car lifted and taken over there to get the STAR Diagnostics readout.
She's done 104,776 miles. I'm sure your right about the 722.6 trans, the RAC guy did mention that to me.
I've got Mercedes Brooklands Surrey literally 5 mins away but I'm quite keen to keep both my arms and legs for quite awhile longer yet )-

 

[Petrol Pete]

It's up to you but you don't need a 'Mercedes gearbox' specialist , the 722.6 is in all sorts of vehicles including Chryslers (Crossfire in the UK for example) any decent transmission shop will be able to deal with it .

It is a very durable unit with few (but well documented) faults ,one odd one is fluid 'wicking' up to the TCM from the (cheap to replace) TCU plug due to an internal leak . If you have a few hand tools this is easily checked DIY with the car still on the floor.

1. Pull the carpet up in the passenger footwell.
2. Unscrew the footplate (4 x 6mm from memory)
3. Unplug the TCU
4. 'Sniff'/look for oil that should NOT be there.
5. No oil ? leaky TCU not at fault.

Like this (in a RHD car)



Thi



This is the plug.

PS. My 2006 C class has the same (slightly modified to suit) transmission , it has done over 150K miles dealing with whatever the 5.4 V8 AMG engine has thrown at it, hang in there.

 

[W1ghty]

Check the gearbox fluid level (buy a dipstick) .
It’s checked when it’s hot . After a 30 minute drive
Engine running on a flat surface, with the gearbox in P .
As above , get the transmission plug changed anyway .