W203 Gearbox issue

[Remmoc]

Gearbox doing a funny thing .
Its happened twice now a few weeks apart but only when its cold .
Basically i pull away as normal and it doesnt change up , pull over and switch between C , S and M . Put it back in S and its fine and changes as normal .
56 Reg C108 Avantgard
Any ideas please

 

[Petrol Pete]

How many miles on the car , and when was the transmission last serviced ?

 

[Remmoc]

130,000 miles , no idea on when the box was last serviced , just wondering as to whats going on really , its fine normally but has done this twice so far and only when cold on initial pulling away

 

[W1ghty]

The boxes are very sensitive to oil level and oil quality . The car may well have logged fault codes .
The cheapest start point is check the oil level when it’s hot .
If topping up improves the problem , then get a gearbox filter/atf service done .
Recommended gearbox service intervals every 40k

 

[Petrol Pete]

OP. Get the transmission service done , then get back to us. 130K with no service record is just way too much. 722.6 service information is all over the web, either DIY or £200/£300 by a good independent mechanic (lock down might make things difficult getting it done any time soon) , checking the level and topping up is the least you should do. But adding a tiny bit of new ATF fluid to 8 litres of dirty burnt ATF is just a sticking plaster.

The box has an electrical conductor plate and hydraulic valve body that is submersed in ATF , when the fluid gets old it causes all sorts of trouble. Do not stress too much , there are many new/refurbished parts available fairly cheaply . A proper service (including draining the torque converter, cooling lines and a new electrical multi plug [£20] ) usually sorts most problems out.

These transmissions are renowned for their strength and longevity and are used in cars and trucks the world over. Just get it serviced.

 

[W1ghty]

Have you got a red tab on the dipstick tube

 

[BlackC55]

Plug it in firstly and read the codes in the box. You probably have a speed sensor issue. When the speed sensor is replaced, the gearbox oil and filter should be done anyway.

 

[Remmoc]

theres no gearbox dipstick unfortunately - only the tube
, where can i get one

 

[BlackC55]

ebay

 

[Datadogie]

Put two marks on the dipstick when you get it one for hot and the other for cold as I don't trust the markers on the ebay ones. This will be good for future reference. That is assuming the levels are right to begin with.

 

[W1ghty]

theres no gearbox dipstick unfortunately - only the tube
, where can i get one

Red tab or black tab buddy ?

 

[Petrol Pete]

The red tab is a show that the transmission is factory sealed , but the red tabs are available to buy on line so is no real indication of much. As W1ghty said, the least you must do is check the ATF level ASAP.

 

[W1ghty]

The red tab is a show that the transmission is factory sealed , but the red tabs are available to buy on line so is no real indication of much. As W1ghty said, the least you must do is check the ATF level ASAP.

The black tab , is factory sealed . The red tab means you may have had an atf change (or someone checked the level)

 

[Remmoc]

its got a red tab

 

[zipdip]

Well that suggests that before you owned the car the gearbox had a ATF change,but given the problems you are having follow the advice already given get it to a indy and get any codes read and then with the indy make a decision,I think it will need a service and a speed sensor .

 

[Petrol Pete]

The black tab , is factory sealed . The red tab means you may have had an atf change (or someone checked the level)

Oops, yes , wrong way around . My bad.

 

[W1ghty]

Oops, yes , wrong way around . My bad.

I knew what you meant