W205 C250 AMG Gearbox Coolant Water Loss

[Rixlk]

Hello, My wife has a 2015 W205 C250 AMG Premium. It is lossing alot of water from the GEARBOX coolant reservoir. Every time I fill the car up with fuel I put approx 1 litre of water in. I've been back to my dealer numerous times, had all pipes etc replaced. There is apparently no water in gearbox or water on the floor. No warning lights appear but for obviose reason very concerned. Anyone else had this fault?

 

[markjay]

Welcome.

Are you sure you mean the gearbox? Not the radiator?

If the car is losing coolant and you need to top-up the coolant expansion bottle regularly, then it could be a leak, or a blown head gasket.

The dealer isn't the best place to get this tested and fixed, you need to find a good MB specialist in your area.

 

[alabbasi]

Gearbox coolant reservoir? Might be a new one for me. If you mean the transmission cooler which is part of the radiator. You need a radiator.

 

[geoffus]

You must have a small hole in the radiator, heater matrix or water pump, on a car of that age I would suspect radiator if you have replaced all the hoses. A small hole that lets a high pressure amount of steam when the car is warm. If it's a very small hole then it would evaporate before leaking on the floor. Who told you gearbox coolant as that is misleading ?

 

[Rixlk]

Please see attached photo of my engine bay. I have TWO coolant reservoirs. One as pictured in the bottom right hand corner with the cap removed that's losing water (transmission / gearbox) and the other on the far left that's engine coolant.

 

[Jobsworth]

I’d say that’s the chargecooler reservoir

 

[Rixlk]

Gearbox coolant reservoir? Might be a new one for me. If you mean the transmission cooler which is part of the radiator. You need a radiator.

Many thanks for your response, I thought the gearbox was the transmission? Anyway, does it have its own independent radiator or is it somehow linked joined to the engine coolant radiator. What's the best way to inspect the radiator / gain access?

 

[alabbasi]

It's usually one radiator but it's easy enough to tell by opening the bonnet and looking at your radiator.
It's right there at the front of your engine.

 

[JHS]

Not another smart alec answer, but if the transmission and engine share the radiator , there will be separate matrix for each. They will be identified by separate inlets and outlets so it should be possible to locate the leak if it is there.
Another source of leak would be hose connections in the system.
Good luck.

 

[Rixlk]

It's usually one radiator but it's easy enough to tell by opening the bonnet and looking at your radiator.
It's right there at the front of your engine.

That's the problem, its been back to the dealer 3 times, and a specialist once. Lots of money spent, no leaks no explanation etc. Looking for someone with in-depth knowledge of W205 C250s who truly knows the system (I know where the radiator is). My dealer's only answer was we'll take it back in as trade. Specialist recommended cutting my losses and giving it to we buy any car. No warning lights and still drives so my plan is let my wife drive it until it goes bang then scrap it. Shame for a 'high end' 15 plate car. Back to Audi for me.

Not another smart alec answer, but if the transmission and engine share the radiator , there will be separate matrix for each. They will be identified by separate inlets and outlets so it should be possible to locate the leak if it is there.
Another source of leak would be hose connections in the system.
Good luck.

After 4 visits to the professionals you'd like to think the radiator would have been thourally inspected. All pipes etc have been replaced at least once at my expense. The radiator can't be visably inspected with bonnet open. My next option is removing the bumper.

 

[E55BOF]

Am I missing something here? Does the C250 actually have a water-cooled gearbox?

 

[Rixlk]

Last attempt with this thread. Please only respond if you have an in-depth knowledge of W205 C250 vehicals. I am very mechanically minded and I'd like to think my dealer and a specialist know what there doing aswell at the rate they've charged me. Please read my original post first. My dealer has even replaced the gearbox oil and found no water in there. All pipes and expansion tank replaced. My question is where is the radiator situated in relation to the engine coolant A/C condenser etc I presume they are all sandwiched in, bumper off? The second is how is this water pumped around the system and where is said pump. Please could responses start with... On a C250 w205 the system...... Not I had a similar fault on my Ford Fiesta......... Sorry for decent honest responders but looking for genuine help not blind guessing.

 

[Rixlk]

Am I missing something here? Does the C250 actually have a water-cooled gearbox?

What's the second expansion tank for then?

 

[Jobsworth]

I’ll try it one more time. It’s the expansion header tank for the charge air cooler. The intercooler if you like. It’s a seperate circuit to the engine coolant. It has nothing to do with the gearbox

 

[Deleted member 149005]

Looks like the windscreen washer bottle to me

 

[Trickythemerc]

Me Too Apart from it having a pressure relief cap.

 

[Deleted member 149005]

Do you have a note of what checks and tests the “professionals” have made?
- head gasket
- pressure test on the coolant system
- if there is no staining from a leak, possibly the water is being lost under pressure as steam?

What colour liquid is is the expansion bottle you are pointing to?

If the coolant system is losing fluid surely there would be other symptoms such as an increase in engine temperature?

 

[Rixlk]

I’ll try it one more time. It’s the expansion header tank for the charge air cooler. The intercooler if you like. It’s a seperate circuit to the engine coolant. It has nothing to do with the gearbox

Many thanks, the system remains pressurised for hours after use, which puts me off pin ***** leak in the system but I'm happy to explore further. How is the water circulated and how easy is it to inspect the system. Dealer and specialist both recommend that I dispose of car ASAP.

 

[geoffus]

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.

 

[Jobsworth]

Leaks could occur anywhere on the system, but it doesn’t hold a lot of water. The pressurisation suggests to me the pump might not be running and the system is boiling itself dry. Surprising amount of heat going on there.