W204 C200 CDI Coolant Level Warning

[Vx-Man-G]

Hi folks,

Just after some help.

In the last 2-3 months we have twice had a coolant level warning come up on the dash. Upon inspection, there does not appear to be any apparent leak anywhere. The coolant doesn't also go excessively low, maybe a little but nothing that would initially alarm, maybe needing a few drops again.

Any ideas what this could be, or what I should look into? Header tank cover and inside the header tank, it is clean, the dipstick is pure oil so nothing untoward noticeable.

Any help would be greatly appreciated.

Thanks.

 

[Steve@Avantgarde]

Check the fuel filter housing, water pump and EGR bypass valves all common problems with slow leaks from there. Fuel filter housings and water pumps have all been modified.

 

[Vx-Man-G]

Sorry to be thick, but any pointers as to where even those are located? Thanks

 

[Steve@Avantgarde]

Lift off the engine cover and you will see the fuel filter. The housing it sits in is also a coolant tube for the thermostat feed. Where it meets the cylinder head is where it leaks. You will see a load of dry crusty coolant around the inlet manifold if its leaking. The EGR bypass unit is bolted to the inlet manifold by the vacuum tank. The water pump is at the front of the engine behind the poly v belt cover.

 

[Vx-Man-G]

Thank you, I will have nose under the bonnet area on the weekend. Appreciate your replies. Thanks.

 

[moj91]

My w204 C250 is now on its second fuel filter/'water collector' unit (the first to be replaced i think was another pre-modification unit so failed again)
The water pump is now leaking at 85k, it is original. I am loosing about 1l of coolant a week from here. EGR bypass seems fine... so far!

Both the fuel filter assembly and water pump both began to leak during the hot few days in July/August this year.

FYI the fuel filter assembly was a PITA to replace, the EGR cooler needs to be removed to access (requiring new gasket and it in itself is a pain to remove. I ended up doing the job myself (regrets!) due to local indie's quoting several hours to do job in labour for a £20 part. (Not sure for those in the know how hard this really is but i could not access the EGR cooler bolts on the underside).
In the end i carefully cut a slot in the old unit beside where the fuel filter sits to enable the component to be squeezed past the one fixed metal inlet/outlet pipe on the egr cooler which restricts access. I did the same on the new part to fit - the slot was in the side of the fuel filter cartridge holder and has made little if any difference to the integrity of the fuel filter holder as it still has support from below and the 2 clamps work on the side. The slot is nowhere near the water pipes which form part of the unit.

I've decided to let my indie do the waterpump as access from below is needed and I do not have a lift!

 

[Vx-Man-G]

Lift off the engine cover and you will see the fuel filter. The housing it sits in is also a coolant tube for the thermostat feed. Where it meets the cylinder head is where it leaks. You will see a load of dry crusty coolant around the inlet manifold if its leaking. The EGR bypass unit is bolted to the inlet manifold by the vacuum tank. The water pump is at the front of the engine behind the poly v belt cover.

Hi Steve, apologies for delayed reply, but had a quick look today and where you pinpointed me and this is what I discovered, almost word for word what you said. Is this definitely going to be where im loosing a little coolant every now and then?

So my question is, what needs changing and how serious is this? £££££....??

Thanks and Merry Christmas.


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[Vx-Man-G]

Morning, it would seem everyone is still on Christmas shutdown
If someone could help/guide, that would be great.

Thanks.

 

[Vx-Man-G]

Hiya, and Happy New Year to everyone with very best wishes for 2018.

Would anyone be able to kindly help me with this please? I uploaded some images and commentary in post #7.

Many thanks in advance...

 

[Vx-Man-G]

@Steve@Avantgarde - Hi, are you able to help please? Many thanks.

 

[Steve@Avantgarde]

EGR bypass housing leaking, common problem. Probably replaced 20 or so in the last year. Bit of a job to replace.

 

[Vx-Man-G]

EGR bypass housing leaking, common problem. Probably replaced 20 or so in the last year. Bit of a job to replace.

Thanks Steve.
Do you think thats definitely the cause of this periodic coolant loss?
What sorts of costs am I looking at to resolve?
Thanks.

 

[Steve@Avantgarde]

If its leaking coolant, of course! 651's are like the titanic, they leak from the fuel filter housing, thermostat housing, water pumps and the EGR cooler housing. Mainly because everything is made of plastic which has a different expansion rate to aluminium and also it flexes and distorts over time with constant heat cycles.

Thats why the water pumps are modified to aluminium and the fuel filter housings have a different bolting position now.

About £400 from an Indie I would say. Double that at a dealer.