W205 C250 AMG Gearbox Coolant Water Loss

[Rixlk]

I found a previous post about your system here, who told you it was a gearbox cooler ?

What is this for? | Engine

Mercedes W205 2015. I've found a bottle which seems to be empty and have no idea what it's for. Last time I've checked all fluids, there was some pink fluid there but now it's completely empty. Does anyone know what that is? Thanks a lot.

forums.mbclub.co.uk

It has its own system for the intercooler.View attachment 104624

Many thanks, we're finally getting somewhere, frustratingly I seem to have the same issue as many other C250 owners. The previous thread didn't appear to come to a conclusion either?

 

[E55BOF]

So the car does not have a water-cooled gearbox. I thought not... Who told you it did? Not your specialist, I hope...

It sounds as though both dealer and specialist can't diagnose the problem, so have just given up trying and put it in the 'Too Difficult' category; recommending disposal of the car without telling you why seems a bit drastic. Is the specialist you are using an MB-registered indie with a STAR, or a 'German Car Specialist'? How did you find him?

Just read Jobsworth's latest post. That sounds like a promising lead to follow next.

 

[geoffus]

may look like this
intercooler

MERCEDES BENZ C Class W205 Turbo Intercooler A2740900414 for sale online | eBay

Find many great new & used options and get the best deals for MERCEDES BENZ C Class W205 Turbo Intercooler A2740900414 at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

 

[Rixlk]

Spot on thank you, the next question is how could I diagnose if this is actually this part I needed. I'd only purchase brand new OEM parts. How is the water evaporating into thin air / wheres it currently going? Is it a DIY job to replace, Id like to class myself as compitent / practical.

 

[rf065]

Has anyone checked the actual water pump? I'm sure these models had the first plastic water pumps that are known to leak after a few years and the replacement pumps are not plastic.

 

[geoffus]

You will have to find it first, I have a similar engine but no separate intercooling system. I wonder if yours is tucked behind a wheel arch out of airflow so needs watercooling. if its a small leak I wonder if the heat from the intercooler is causing it to evaporate.

 

[Deleted member 149005]

How is the water evaporating into thin air

I think you’ve answered your own question...

 

[Rixlk]

You will have to find it first, I have a similar engine but no separate intercooling system. I wonder if yours is tucked behind a wheel arch out of airflow so needs watercooling. if its a small leak I wonder if the heat from the intercooler is causing it to evaporate.

View attachment 104630

Im happy to strip the car back myself but I'd love to know first where other owners eventually diagnosed the fault to be from. Someone has suggested the pump, mine is an early W205.

 

[rf065]

Im happy to strip the car back myself but I'd love to know first where other owners eventually diagnosed the fault to be from. Someone has suggested the pump, mine is an early W205.

I've copied this from another post to see if it helps you,

"I had a problem wit my water pump on my w204 2011 model.
First symptoms were indication on warning light that I had to top up coolant. This I did and after 155 miles I had the same warning. Could not find any leak whatsoever. Next warning after 100 miles, I then added a dye which I obtained from Ebay, leak was from bottom drain hole of the water pump, shaft seal was leaking. New pump fitted. Problem solved. I understand that on my model / year the water pumps were suspect, I believe it is a common fault."

 

[E55BOF]

That's the engine coolant pump, though, and the OP's problem is with the intercooler cooling system.

 

[Jobsworth]

I don't really deal with many four cylinder petrol Mercs, but on the W205 C63 there are two chargecooler pumps, and they do commonly fail. They never store a fault code in the engine ecu though, the fault is always in a module called "AMG drive unit"

 

[geoffus]

That's the engine coolant pump, though, and the OP's problem is with the intercooler cooling system.

Principle would be the same though.
If the car was treated to a dye and left running to get hot maybe you would see a dye with a ultra violet light. if the car was left to just tick over the intercooler would not be warm and a leak more evident, but the pump, if you can find it, is suspect.
I do wonder what coolant pipes were changed by your garage if they thought it was transmission cooler and if the pump was checked ?

 

[GeeJayW]

Is it a C250d with the OM651 engine? If so, check out:

Mercedes Benz OM651 Diesel Engine Service Manual .pdf

Mercedes Benz OM651 Engine Workshop Service and Repair Manual Introduction Into Service OM-651 DE 18 LA red, DE 18 LA, DE 22 LA red, DE 22 LA

mbmanuals.com

I'll see if I can can again find a free download link (I found one before, but some time ago)..

Looks like the cooling element is along the bottom of the main radiator. Could be damaged by aggressive use of a pressure washer or a stone strike...

 

[rf065]

That's the engine coolant pump, though, and the OP's problem is with the intercooler cooling system.

Do we really know that though? My w205 & my SLC both have these two reservoirs for coolant, in both, one is a small reservoir and the other is a larger one. The OP appears to be saying the larger one is requiring top ups, in mine, the smaller reservoirs appeasr to relate the the intercooler, the larger one is the main coolant system.

 

[E55BOF]

If I read the thread correctly, the reservoir that empties is the one at the left front corner of the engine bay, and that's the intercooler system expansion tank.

 

[GeeJayW]

So the white one on the right of this picture (left or near side of the car)?

 

[rf065]

If I read the thread correctly, the reservoir that empties is the one at the left front corner of the engine bay, and that's the intercooler system expansion tank.

On both of mine the front reservoir is the larger main tank, the smaller reservoir which I assume is for the intercoolers is at the rear of the engine?

 

[E55BOF]

So the white one on the right of this picture (left or near side of the car)?
View attachment 104650

As I understand it, that's correct. See the picture in post #5. Rf065, the setup on both your cars must be different to the OP's.

 

[FiveAlive]

I think you’ve answered your own question...

Principle would be the same though.
If the car was treated to a dye and left running to get hot maybe you would see a dye with a ultra violet light. if the car was left to just tick over the intercooler would not be warm and a leak more evident, but the pump, if you can find it, is suspect.
I do wonder what coolant pipes were changed by your garage if they thought it was transmission cooler and if the pump was checked ?

Definitely dye is a good idea to look for the leak. I'm suprised by the actions of the garages involved anf their failure to figure it out. A bunch of amateurs on a web forum guessing wildly is one thing, but you'd like to think that an MB service agent would know about the latest gubbins to have been shoe-horned under the bonnet.

I assume that the intercooler in this case is an air-water design so a leak between the passageways in that would allow the fluid to escape into the inlet manifold and, eventually, out of the exhaust 'into thin air'. I suppose such a leak could also mean that when on boost the air could pressurise the water circuit and might cause fluid to escape from the filler cap, too.

When I've previously had coolant circuit issues on another car, it exhibited surprisingly strange symptoms: completely watertight when cold and when hot, but leaking like a sieve when warm. I was losing coolant regularly but couldn't see where until I happened to stop the car after a journey of just the right length and saw the puddle forming.

 

[geoffus]

Im happy to strip the car back myself but I'd love to know first where other owners eventually diagnosed the fault to be from. Someone has suggested the pump, mine is an early W205.

Have you had any joy yet ?