Help , coolant consumotion in c250 cdi w204 2010

[Dr Somashekar v]

Hello all,
I own a 2010 w204 c250 cdi in india and have done about 146000 km . Around 6k km ago I had a problem with low coolant level and water pump , thermostat , fuel rail was changed . There was no problem until recently when I found low coolant warning again , 500 ml of water was used to refuel the reavoir upto the optimal level .on further driving 1000km later same problem occured . I examined the coolant system , no visible leak was seen . There was no oil mixture seen in coolant tank nor was a thick filament seen on the reservoir cap . On inspection of the dipstick there was no signs of coolant mix . There seems to be collection of a fluid on top of the engine block which I've marked using the red arrows . There has been no increase in the running temp of the car. I've will post picture of finding on inspection of the car . I humbly request the memebers of this forum to provide their valuable input as to culprit and the subsequent action to be taken actions to be taken . Thank you in advance !

 

[ajlsl600]

put cardboard under engine (first remove plastic undertrays,if fitted ) pressurize the cooling system to system rated pressure and look for sign of water on cardboard .

 

[Dr Somashekar v]

put cardboard under engine (first remove plastic undertrays,if fitted ) pressurize the cooling system to system rated pressure and look for sign of water on cardboard .

Thank you for the reply sir . Unfortunately at the moment I cannot perform the test due to unavailability of facilties , are there any simple tests which would help to asses the seriousness of the leak and the source?

 

[ajlsl600]

Thank you for the reply sir . Unfortunately at the moment I cannot perform the test due to unavailability of facilties , are there any simple tests which would help to asses the seriousness of the leak and the source?

think you already done that .you know water is disappearing and you know how much you need to add per 1000 km . you seem to know oil level not increasing ,that being the case so its leaking externally or into induction system. ? cheapest investigation at moment,in my view as previously outlined .i am guessing the coolant tank cap seal is in good order .?

 

[Dr Somashekar v]

think you already done that .you know water is disappearing and you know how much you need to add per 1000 km . you seem to know oil level not increasing ,that being the case so its leaking externally or into induction system. ? cheapest investigation at moment,in my view as previously outlined .i am guessing the coolant tank cap seal is in good order .?

Sir , there seems to be no leaks around the coolant cap and of late I think the problem has become worse , there is a consumption of 1 litre for every 100 km . The nearest MB dealership is around 300 km from my place . So sir what I'm trying to figure out is if it's safe to drive the car with topping up the fluid or should I get the car towed mediately to the service station .

 

[ajlsl600]

Sir , there seems to be no leaks around the coolant cap and of late I think the problem has become worse , there is a consumption of 1 litre for every 100 km . The nearest MB dealership is around 300 km from my place . So sir what I'm trying to figure out is if it's safe to drive the car with topping up the fluid or should I get the car towed mediately to the service station .

having made sure no water running out, i think yr safe to travel ,and stop add water as required add warm water ,not cold .and watch yr temp guage i assume its working ? see that it stays in or near yr normal range

 

[Dr Somashekar v]

having made sure no water running out, i think yr safe to travel ,and stop add water as required add warm water ,not cold .and watch yr temp guage i assume its working ? see that it stays in or near yr normal range

Ok sir thank you

 

[drmw]

I think with 1 litre per 100 km it is going to get worse - is there not a non mercedes dealer closer to where you are? Water leaks should be pretty common across the board - what about the dealer who did the other stuff?

 

[Dr Somashekar v]

I think with 1 litre per 100 km it is going to get worse - is there not a non mercedes dealer closer to where you are? Water leaks should be pretty common across the board - what about the dealer who did the other stuff?

The previous repairs was done in Bangalore , in the place in staying currently is a town which is around 300 km from blr . No MB dealership here

 

[steveq]

Hi,

It could be your the fuel filter housing that is leaking. That is a common fault on the OM651 engine and there was a revised design.

 

[joderest]

be aware.
watch the coolant with engine running, i bet it rises and forces out of the expansion tank, if so i would suspect head gasket gone between cylinder and water jacket and the system is being pressurised.
A decent garage would have a tester to see if combustion gases in the coolant. If you DO have this problem (which i have at the moment on the wifes car) you could do more damage by just topping it up and driving.
Get it checked.
It could also be a thermostat stuck in the closed position. or partly closed.

 

[Dr Somashekar v]

Hi,

It could be your the fuel filter housing that is leaking. That is a common fault on the OM651 engine and there was a revised design.

Hello sir , thank you for the reply. As far I could see from I found a collection of liquid near the fuel filter housing .

 

[Dr Somashekar v]

H

be aware.
watch the coolant with engine running, i bet it rises and forces out of the expansion tank, if so i would suspect head gasket gone between cylinder and water jacket and the system is being pressurised.
A decent garage would have a tester to see if combustion gases in the coolant. If you DO have this problem (which i have at the moment on the wifes car) you could do more damage by just topping it up and driving.
Get it checked.
It could also be a thermostat stuck in the closed position. or partly closed.

Hello sir , thank you for the reply .
The thermostat was replaced recently , and I don't find any leaks from the coolant reservoir , I've observed it when the engine is running . Is there thing else I should be looking our for in the car ?