om651

Tony Dyson

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Aug 26, 2018
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Location
God's Country
Your Mercedes
2014 C 220 CDI W204 OM 651
My OM651 temp rises slowly to 83°C and stays there all day within 1-2° and between Summer/Winter takes between 10/15 Mins to reach set point temperature.
 

Dean Fletcher

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Mar 24, 2018
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Location
Penrith, Cumbria
Your Mercedes
Mercedes E400
Is that just on initial warm up though? I thought it was normal that as thermostat opened for first time then the temperature would drop down a little as the cold water mixes with the hot. Mine always goes straight up to 98 in about 2 or 3 minutes and then as the thermostat opens it drops down very quickly to 90ish. Has always done that since I put a brand new MB thermostat in and all my other mercs have done that... then slowly creeps up to running temp and maintains it there.
Mine goes up quick then say if I'm going down a huge hill it drops back a little because there's acceleration. On the way to work today it got right up to 87 degrees and stayed there all good I suspect
 

d215yq

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Mar 28, 2008
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Age
39
Location
Valencia, Spain
Your Mercedes
1987 W124 300D 280k miles
Mine goes up quick then say if I'm going down a huge hill it drops back a little because there's acceleration. On the way to work today it got right up to 87 degrees and stayed there all good I suspect

Mine definitely goes down on hills, but I think I read somewhere that old mercs use a temperature gauge that reads "real temp" so it's quite normal to see many fluctuations as the terrain/speed changes (all my W124s do that) whereas almost any other car from 80s onwards read what the ECU expects compared with actual temperature and adjusts accordingly so that it is always exactly the same temperature on the gauge even though this is impossible in real life.

Hence a normally working new car will read exactly the same no matter what even though the engine temperature is actually fluctuating on up/downhills. So any variations on the gauge of a newer one could signify a problem but I'm guessing not if it's just a bit of cooling going down hill.
 

Dean Fletcher

Senior Member
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Mar 24, 2018
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Location
Penrith, Cumbria
Your Mercedes
Mercedes E400
Mine definitely goes down on hills, but I think I read somewhere that old mercs use a temperature gauge that reads "real temp" so it's quite normal to see many fluctuations as the terrain/speed changes (all my W124s do that) whereas almost any other car from 80s onwards read what the ECU expects compared with actual temperature and adjusts accordingly so that it is always exactly the same temperature on the gauge even though this is impossible in real life.

Hence a normally working new car will read exactly the same no matter what even though the engine temperature is actually fluctuating on up/downhills. So any variations on the gauge of a newer one could signify a problem but I'm guessing not if it's just a bit of cooling going down hill.
Yeah I know what you mean. Mines 9 yr old now. At one point I was going to get the thermostat replaced haha.
 

steveq

Senior Member
Joined
Jun 9, 2010
Messages
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Location
Dublin
Your Mercedes
2011 Merc S212 E220CDI Estate; Tesla Model 3; 1965 W113 Merc 230SL Pagoda
can i ask mileage at pump replacement and cost of parts.?

I replaced the water pump on my S212 E220 a month or two ago.

The mileage on the car was about 108,000 and it is 8 years old.
I can see water pumps online for £165 -- these are for genuine MB parts. I paid more for mine as I bought it from a main dealer as I wanted it quickly.
The only other thing you will need is replacement coolant.
 

Rash777

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Sep 10, 2019
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Location
South Africa
Your Mercedes
C250 Cdi 2013 OM651
Hi all, I know this thread is a few months old, but I need some help here, been searching on lots of forums and come up with nothing helpful, my w204 c250 CDI 2013 model, limp mode, engine light on, after scanning it comes up with an air mass sensor error.

So just for some history, 4 months or so ago, it did this, I sent it to a mechanic who told me I need to get an airflow meter, long story imported one and it took just over a month, changed it still the same. then he had the car with him for 2 weeks. Called me and said that it was fixed, collected it paid a small fortune, the car went perfectly fine for about 3 months.... then last week same problem. Now, this guy has moved his workshop and is nowhere near me anymore. He says I need to get it to someone local to repair at my cost.


Really I am just tired of being messed around and lied to so I want to check as much as I can myself. I have worked on plenty of my own cars in the past so hopefully, I can DIY or diagnose this. apparently he fixed the following, DPF regen and clean, EGR strip and clean, and then (Front Control SAM unit repairs). Now I opened in front where the SAM unit is and it does not look like it was ever opened.


Any advice would be very helpful.
 

John Laidlaw

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Joined
Nov 15, 2013
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Location
Wirral
Your Mercedes
Land Rover Discovery 4
Welcome, lots of good indies in here who are totally reliable, let us know your location and we can recommend your nearest...whoever your disappearing guy was sounded like he was talking a load of old bollocks !
The 651 has its foibles but the indies on here have experienced all of those and more and will cut to the chase after a simple MB specific diagnostic in most cases or pure specific experience
 

LostKiwi

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Aug 25, 2006
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Location
Midlands / Charente-Maritime
Your Mercedes
'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
Hi and welcome. John covered it perfectly above.
 

Rash777

New Member
Joined
Sep 10, 2019
Messages
3
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0
Location
South Africa
Your Mercedes
C250 Cdi 2013 OM651
Hi John, Sorry I totally forgot to add my location, I am in South Africa, Johannesburg specifically. From what I find is that a lot of the things he said was a load of lies. I also got a guy that works for Mercedes that came with the Xentry unit which is what they use at the dealers and did all sorts of tests including the DPF regen and vacuum tests and boost leak test. Did not find anything except air mass sensor ground to earth if i am remembering correctly.
 


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