There is a coolant leak in the W204 C250.

[Starcar2022]

Greetings, everyone.

Apologies for revisiting a recurrent issue.

I just acquired the automobile a few days ago. Upon collection, I extensively tested the vehicle by driving it for a significant distance. I then proceeded to drive it for 60 miles to my house, used it for commuting to work the following day, and returned home. However, in the evening, I received a warning indicating that I needed to top up the coolant. Upon inspection later that evening, I discovered that the whole expansion tank was devoid of fluid, so I proceeded to replenish it.

While commuting to work, the caution indicator reappeared. Upon further inspection later in the day, it was seen that the expansion tank remained devoid of any liquid. Refuelled and shortly after driving 5 miles this morning, the alert reappeared.

After doing a search on Google, it seems that the problem I am experiencing is rather prevalent. I have come across several sources discussing potential places of leakage, but I am uncertain as to where I should direct my attention. I will bring it to the garage for inspection. However, in the meanwhile, could anybody provide any guidance on where to look for visual signs of the leak? Given the large amount of coolant, it is reasonable to expect that there should be visible signs of it. However, I am uncertain about where to begin looking.

Thank you.

[Rudy7831]

[Starcar2022]

Is the fuel filter housing situated on the right side of the engine, while the water pump is positioned at the front? Is that accurate?

[BENZE220AMG]

To identify potential water pump issues, it is advisable to inspect two often seen areas for any indications of water leakage or the presence of water residue. Specifically, pay attention to the top pulley on the engine, since this is where the water pump is located. The fuel filter housing is located behind the fuel filter, deep down below the pipes at the intake manifold on the engine. Look for accumulations of water around the black plastic underneath.

[Starcar2022]

Great, I will prioritise examining them first and proceed accordingly.

[nimbuye5]

The water pump, fuel filter housing, and thermostat are the most often seen components. However, coolant hoses and radiators leaking are a very close second in terms of frequency.

[Starcar2022]

Where is the Thermostat typically situated? The whole engine seems to be a jumble of haphazardly arranged pipes in my perception.

[nimbuye5]

Following the upper hose.

[Starcar2022]

Thank you for your response. I will examine everything later tonight.

If you were in close proximity, I would retrieve it.

[Starcar2022]

After taking the time to examine the situation, I am confident in my assumption that the issue lies in the fuel filter housing. The pump and thermostat seem to be in good condition.

Both bolts seem identical.

Can this be done as a do-it-yourself project? I am not used to working on automobiles and I do not own an extensive array of tools. However, if the task just involves removing items without the need for any specialised equipment, I believe I would be capable of doing it.

[motorman3]

Indeed, it is a do-it-yourself project. I successfully completed mine. No specialised tools are required; only a high-quality quarter inch socket set is necessary due to limited access.
It is essential that you get the 3 hole housing. (There are two existing leaks and another one will soon develop. It took me around three hours since the EGR cooler also has to be removed.)
It is possible that your cylinder head may or may not include three threaded holes. In the case that it does not, just disregard the third bolt.