Another 250CDI (W204) Coolant Leak Issue

[MarkII]

Hi, my name's Mark and my car has a drinking problem...

It all started in November, when I noticed that she'd started knocking back the juice a bit, well to be honest about a quarter of a litre every 100 miles. After some heated 'discussions' in the garage about what the hell she was doing, we decided not to approach AA but to go and get some advice.

A visit was arranged to our local MB 'clinic' in early December and they diagnosed she had a faulty pump. After some difficulty getting hold of one, a new one was fitted but unfortunately she continued to drink heavily throughout Christmas and into the New year - in one journey alone she downed about 1.5 litres in 600 miles.

Thankfully she wasn't so far gone as to start leaving embarrassing puddles in the car port but it could only have been a matter of time.

Today she's been taken back to the 'clinic' and they've diagnosed a faulty seal on her EGR valve. The new seal should be fitted by the end of the day, following which I hope her habit will disappear as swiftly as it arrived!!


Mark



On a serious note, there's clearly an ongoing issue with the coolant system on the 250CDI engine, as evidenced by the fact that there are no water pumps available from MB and the dealer had the EGR seal on the shelf.

I was pretty unhappy at having to fork out for the pump to be replaced on a Mercedes with less than 50k on the clock but the fact that the seal on the EGR has also needed replacement just goes to show you can't assume it's always the pump.

The dealers comment that the seal had 'become faulty' didn't go down well with me and now both jobs will have been carried out with a 50% contribution from MB (I suspect if I lived across the pond the whole job would have been free but that's the way the cookie crumbles).

 

[h5nnd]

Have they checked every possible avenue, as my experience with some dealers is they will replace the obvious first, without real diagnosis, the amount of arguments i have had with dealerships is unreal.

The new cdti Vauxhalls have the very same issue with coolant loss on a huge scale petrol and diesel, i know they aint on a par with Mercedes but, funny you have mentioned the egr seal as they suffer the same issue, as well as the egr cooler leaking coolant, res caps, cracked res tanks, weeping radiators, hoses etc the list is endless. It amazes me still the sheer amount of issues the new diesels have with them, egrs, dpfs, manuals and their dual mass flywheels, makes me wonder why we buy them.

Have they done a pressure test?? I would ask them.

 

[Southy1978]

Both very common failures along with the cylinder head connection fitting! It will be the egr cooler bypass flap seal you had changed. I hope it sorts the leak out for you!

 

[MarkII]

The system has supposedly been pressure tested 4 times now (before and after both sets of work) and I'm keeping an eagle eye on the level.

Notwithstanding an air bubble, I hope it will settle and the coolant loss issue will have been fixed.

Thankfully I trained (albeit 30 odd years ago) in automotive engineering and have kept up my knowledge base as much as possible, so I'm slightly less susceptible to the kind of 'Fairy tales' some service staff are inclined to try on the general public...

 

[Tim203]

Have they checked every possible avenue, as my experience with some dealers is they will replace the obvious first, without real diagnosis, the amount of arguments i have had with dealerships is unreal. The new cdti Vauxhalls have the very same issue with coolant loss on a huge scale petrol and diesel, i know they aint on a par with Mercedes but, funny you have mentioned the egr seal as they suffer the same issue, as well as the egr cooler leaking coolant, res caps, cracked res tanks/QUOTE]

A friend of mine had a similar issue with a seat Leon R model. The EGR coolIng circuit had a fracture and therefore the engine consumed water when the valve was open.