Thermostat Problem?

survey

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I have noticed over the last few weeks that the temperature gauge instead of climbing (albeit slowly) to 90 degrees, has climbed steadily to 75-80, then up to 80, then hovers between 75 and 80. Sometimes it then goes to 90 but I can force this by dropping a few gears and revving until the needle climbs to 90 and maintains that.

The engine has always taken 20-30 minutes to get to temperature but maybe a bit longer recently to get to 80 degrees. Does this indicate a faulty thermostat or is it the warmer weather? I don't think it is dpf regeneration beacue the ECO light is green most of the time.
 

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The easy way to tell is to start up and let the car get to 40c, then feel the bottom hose , and this should be cold until the thermostat opens at 87c plus
 
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survey

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The easy way to tell is to start up and let the car get to 40c, then feel the bottom hose , and this should be cold until the thermostat opens at 87c plus

Looks a real problem getting to the bottom hose. No room at all.
 

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OK the the rad should not be hot
 

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I'd be holding the top rad hose :lol:
 
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Definitely a faulty thermostat. I had the same problem and after replacing the gauge is constant irrespective of weather.
 
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survey

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Well, I have just had a call from my MB dealer and am informed that the constant temperature should be 80-82 degrees. However this car over 16000miles and my previous MB diesel over 36000miles have settled at a constant 90 degrees.

Can anyone confirm what the gauge should read? Also would constant running at 90 cause a cylinder head problem?
 
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survey

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Well, I have just had a call from my MB dealer and am informed that the constant temperature should be 80-82 degrees. However this car over 16000miles and my previous MB diesel over 36000miles have settled at a constant 90 degrees.

Can anyone confirm what the gauge should read? Also would constant running at 90 cause a cylinder head problem?

To be precise I think the gauge is reading 87 degrees rather than 90 when settled on a run. What concerns me is that no mechanic has ever pointed out to me that the temperature is too high when my cars have been in for a service!
 

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So this car is an 212 250cgi
 
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survey

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So this car is an 212 250cgi

No Malcolm. The car is a 250cdi E coupe 2012. Two things concern me. The fact that my dealer says the temperature should be 82 degrees and mine has always gone up to 87 and stayed there, the other is the hunting between 80 down to 75 for a while say half an hour until then rising to 87 and staying there.

I dare say no damage is done with the car being at 87 rather than 82 (assuming this 82 degree figure is correct). Howver the car has done 16K at this temperature and my previous cdi the same and the dealer never picked it up! Looking at various online forums I note that many owners report their cars running at 90 degrees and being told that is the norm!
I am sure the hunting between 80 and 75 is a more recent occurrence.

The car is booked in for next Monday for diagnostics and then replacement parts if necessary.
 

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Sorry I was sleeping and forgot that the coupe was the 207, this is just a touch to new for my EPC to check on the temp of the thermostat
 
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survey

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Sorry I was sleeping and forgot that the coupe was the 207, this is just a touch to new for my EPC to check on the temp of the thermostat

And do you know Malcolm, I thought that you always had the answer to any problem!
 

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And do you know Malcolm, I thought that you always had the answer to any problem!
I do have a newer version to install at some point in time,but only ½ the info on this engine :(
 
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survey

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No Malcolm. The car is a 250cdi E coupe 2012. Two things concern me. The fact that my dealer says the temperature should be 82 degrees and mine has always gone up to 87 and stayed there, the other is the hunting between 80 down to 75 for a while say half an hour until then rising to 87 and staying there.

I dare say no damage is done with the car being at 87 rather than 82 (assuming this 82 degree figure is correct). Howver the car has done 16K at this temperature and my previous cdi the same and the dealer never picked it up! Looking at various online forums I note that many owners report their cars running at 90 degrees and being told that is the norm!
I am sure the hunting between 80 and 75 is a more recent occurrence.

The car is booked in for next Monday for diagnostics and then replacement parts if necessary.

In fact my original posting of the temperature was correct - it is indeed 90 degrees if not a very little higher. As I say it has been like that since the car was new 16000miles ago!
 

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In fact my original posting of the temperature was correct - it is indeed 90 degrees if not a very little higher. As I say it has been like that since the car was new 16000miles ago!

This is the same for all engines within 3º and sounds much better :D
 
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This is the same for all engines within 3º and sounds much better :D

Hi Malcolm. But the dealer is insisiting that the engines should NOT be running at 90 or indeed anything over what they say should be 82 degrees. I am quite concerned about this and cannot find what MB actually recommend as their standard, particularly as this car and my previous cdi engined MB always run/ran at 90 degrees.
 

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I always understood that 90 was the most efficient temp.

What I did do was to check on the EPC to see what the temp range of the thermostats was, but they have stopped putting that info in now., so I drew a blank

80 is so low that you would never get the heater hot in winter
 
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survey

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I always understood that 90 was the most efficient temp.

What I did do was to check on the EPC to see what the temp range of the thermostats was, but they have stopped putting that info in now., so I drew a blank

80 is so low that you would never get the heater hot in winter

Exactly what I thought. Just checked our other car, a Skoda Yeti, and that sits at 90 degrees. So why on earth would my dealer quote 82 degrees? Shame your EPC no longer shows the temp range.

Perhaps another cdi owner can let me know what temp their car runs at?
 
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Mine is a C220 but I guess should run at a similar temperature.

Mine runs at 92 on the gauge.

Like yours, mine would steadily rise to this temperature but recently in the hot weather goes to 80 and then drops back to 75, cycles like this for a while before eventually getting to 92 and sticking there after 20-25 mins. My thermostat was replaced 2 months ago.

Simon
 
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Mine is a C220 but I guess should run at a similar temperature.

Mine runs at 92 on the gauge.

Like yours, mine would steadily rise to this temperature but recently in the hot weather goes to 80 and then drops back to 75, cycles like this for a while before eventually getting to 92 and sticking there after 20-25 mins. My thermostat was replaced 2 months ago.

Simon

Hi Simon - thanks for your timely response. Just to recap you are saying that your car sits at 92 degrees (that's exactly what my C220 did and what my present car does).
Are you also saying that the going to 80, back to 75 etc etc and then up to 92 is what is does NOW after the thermostat has been changed or was this how it was performing BEFORE it was changed?
 
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