C220 CDI W204 2008 - EGR valve and cooler - coolant leak
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Junior Member
Joined: May 2015
Posts: 42
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From: Essex, UK
C220 CDI Sports Auto, 2008 with OM646.811 engine and 5 speed auto gearbox 722.640
C220 CDI W204 2008 - EGR valve and cooler - coolant leak
Hi Guys,
On my OM646.811, C220 CDI W204 I occasionally get coolant low level warning almost every 1200 miles. So I top it up with with water approx 150 - 200ml - this is normally enough to submerge the coolant sensor into the liquid and for the on screen message to go away. I do roughly 4000 miles / month.
I think I do know where the leak is since it started happening about 2 months ago. On close inspection I found a smear on EGR valve and cooler unit (photo attached). If I clean this, it comes back after almost 250 miles and stays there like that.
The reason for my post is to find out if this is a known issue with w204s also what can cause this and does this needs investigating further or the gasket replacement is a simple cure or even attempting to tighten the torx screws a bit. Also does this unit only carry coolant and no oil ?
Thanks in advance.
Last edited by atom-ant; Jul 11, 2015 at 11:56 PM. Reason: added photo
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Joined: Mar 2008
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From: 1 hours drive north of Sydney Australia
2007 W204 220CDI Classic Sedan
Hi Guys,
On my OM646.811, C220 CDI W204 I occasionally get coolant low level warning almost every 1200 miles. So I top it up with with water approx 150 - 200ml - this is normally enough to submerge the coolant sensor into the liquid and for the on screen message to go away. I do roughly 4000 miles / month.
I think I do know where the leak is since it started happening about 2 months ago. On close inspection I found a smear on EGR valve and cooler unit (photo attached). If I clean this, it comes back after almost 250 miles and stays there like that.
I have not experienced it with my 220CDI .
If it were me I would try tightening the screws a little keeping in mind the threads are alloy. Therefore not too much. See attached torque values
The reason for my post is to find out if this is a known issue with w204s also what can cause this and does this needs investigating further or the gasket replacement is a simple cure or even attempting to tighten the torx screws a bit. Also does this unit only carry coolant and no oil ?
Thanks in advance.
If it were me I would try tightening the screws a little keeping in mind the threads are alloy. Therefore not too much.
Last edited by Carsy; Jul 12, 2015 at 05:39 PM.
Thread Starter
Junior Member
Joined: May 2015
Posts: 42
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From: Essex, UK
C220 CDI Sports Auto, 2008 with OM646.811 engine and 5 speed auto gearbox 722.640
Hello, i performed tightening of screws just a little bit but this did not resolve the issue. I am now going to order the 2x gaskets involved and replace them with correct torque recommendations. Will be using Carsy's guide for removal. Will come back and feed back once done.
Thread Starter
Junior Member
Joined: May 2015
Posts: 42
Likes: 2
From: Essex, UK
C220 CDI Sports Auto, 2008 with OM646.811 engine and 5 speed auto gearbox 722.640
Solved - C220 CDI W204 2008 - EGR valve and cooler - coolant leak
Gasket changed today part 144 /142 in attached. Did it myself. The coolant had to be drained first. A bit tight and fidley job but happy with outcome. Used OE Merc parts and Merc blue coolant.
1.5 hrs it took me.
Thank you all for your support. Thanks @carsy
1.5 hrs it took me.
Thank you all for your support. Thanks @carsy
