W204 C220d Gearbox Transmission Oil Cooler Leak

PatrickHogan

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I'm hoping someone here will have encountered this issue before and knows how best to fix it :)

I have noticed an oil leak coming from the Gearbox Transmission Oil Cooler - part number A0995002300 (seems to be similar to A0995001100 used on the W212 also)

The car is a W204 C220d auto 2014 with 150k miles.
Auto gearbox was serviced by Mercedes main dealer at 100k miles.

See attached photos.

The oil cooler naturally leans back slightly forwards, away from the engine.
The oil pools on the top of the cooler itself.

2 metal pipes and 2 rubber hoses connect to the cooler.
I suspect that an o-ring has perished somewhere and is allowing oil to trickle down.

I cleaned up the fluid from the top of the cooler with a paper towel, but it returns again after a long drive.

1. Can the o-rings be replaced? Or do I need a new oil cooler and/or hoses?
2. Does anyone have a workshop guide on how to replace this part. Is it a DIY job or more involved?
3. Does transmission oil flow through these hoses whith the engine cold and off?
4. I assume that the gearbox oil would need to be topped up after any work is carried out. Where/how do I check this?
Do I need a special dipstick and is it temperature dependent?

Thanks in advance
 

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Dodipops

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I’ve seen similar, that turned out to be the cooler itself, yes fluid will come out not under pressure with everything off.

You have to fill from the drain plug at the trans sump. I’m sure the procedure will be on here somewhere.
 

Jobsworth

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One or two...
Straightforward job to replace it. There are some wire clips that hold the pipes in. You’ll need to detach the little covers to pull them out. Otherwise easy peasy
 
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PatrickHogan

PatrickHogan

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You have to fill from the drain plug at the trans sump. I’m sure the procedure will be on here somewhere.
The trans sump drain plug is underneath the car, correct? Is it under a cover?
Also, do Mercedes sell 1L top up bottles of transmission oil?

Did a search, but couldn't find the procedure.
I'd be grateful if anyone has the link.
Thanks 🙏
 

Dodipops

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Yes on the the trans sump pan.
Have to remove the rear most umdertray.

Don’t have the actual procedure but you squirt it up through the drain hole until it runs out, put the plug in, then you start the car run it through the gears, need a diag to monitor the trans temp, fill it again through the drain hole and it should run out, once it gets to 40•c it should drip one drip every second.

Merc or eurocarparts sell the oil in 1litre bottles.
 
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PatrickHogan

PatrickHogan

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I was at the Mercedes Parts desk a few days ago. They did not have the 1 Litre top up bottles of transmission fluid, only a large 5 litre bottle. They asked if I wanted the red or the greenish blue fluid? Pretty sure the fluid pooling on top of my oil cooler is the blue one. I'm assuming the red and greenish blue fluids shouldn't be mixed? Is the W204 fussy about the type of transmission fluid it uses? Would this one be corrrect? febi bilstein 33889 -it's MB 236.15 spec and blue! (The red fluid seems to be MB 236.14 spec)
 

geoffus

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I was at the Mercedes Parts desk a few days ago. They did not have the 1 Litre top up bottles of transmission fluid, only a large 5 litre bottle. They asked if I wanted the red or the greenish blue fluid? Pretty sure the fluid pooling on top of my oil cooler is the blue one. I'm assuming the red and greenish blue fluids shouldn't be mixed? Is the W204 fussy about the type of transmission fluid it uses? Would this one be corrrect? febi bilstein 33889 -it's MB 236.15 spec and blue! (The red fluid seems to be MB 236.14 spec)
You need the blue fluid, here it is in 1ltr bottles.

You will also need an adaptor to screw into the transmission sump,
I did a full service on mine last year, so you may find the procedure helpful
 
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