W202 220 CDI low engine temperature

[ardisulo]

First of all congratulation for this wonderful forum which brings us all together!
I have a W202 220 CDI engine car, owned for about three years by now. Everything is smooth really enjoy riding this great car.
Two years ago I started having problems with the engine operating temperature. It would go to about 50~60 Celsius on highways (in winter, outside temperature about 12 Celsius). Due to that I replaces my thermostat with a BEHR-Mahle aftermarket thermostat, and same thing as before.
After that, I imagined that maybe this is a standart operating temperature in highways, but some months ago reading at the forums, I thought maybe the thermostat was faulty. So two days ago I changed with another one (same model BEHR-Mahle thermostat) and went for a drive to see the performance, and same thing again. When I enter in a highway at 90km/h, the temperature gauge starts decreasing.
In this case I asked if there was another brand of this thermostat, and they suggested me a brand "Motorad" which I never heard of.
Anyway I was thinking maybe the low temperature is linked to another problem and not the thermostat.

My question: Is there any other problem linked with the low temperature other than the thermostat? Or it is possible that the two thermostat I changed BEHR may have been faulty?

Thanks in advance!

 

[bran.c]

You could test the thermostat on the cooker in a large pot of water, bring it to the boil and see if its working

 

[Dec]

Get the correct thermostat for your car from Mercedes dealer, thermostats have different temperature ratings, for example, mine is 87°, yours is diesel so not sure what temperature rating you need. What temperature is stamped on the last thermostat you bought?

Dec

 

[ardisulo]

Well I did test the thermostat and it did open in boiling point.
The problem is that when the engine temperature is about 60 Celsius the hose that connects the thermostat to the radiator is hot.
So my guess is that it may be probable that the two thermostat I tested are faulty (even though they are OEM quality BEHR, the same that mercedes CDI engines are sold), or that there is another component in the car that allows water to recirculate in the cooling system.
Could this be an issue with the water pump?
Also the thermostat is 87 Celsius written on it.

 

[Dec]

The thermostat is what allows water into the top hose and on into the radiator to circulate through the water pump, it should remain shut until the temperature is about 87°c its very odd that its opening before the temperature rises to 87°.

Is the tube to the heater duo valves getting hot?

Dec

 

[ardisulo]

Yes the tube to the duo valve are very hot. Also the duo valves are hot too.
And the engine temperature when I checked them was 60 Celsius from idle (so the engine was not running before and the top hose that goes to the radiator was hot).
Any ideas? Or you think that I should try the other aftermarket thermostat Motorad, and see if things are different?

P.S: Also to mention the car has had before a pre-heating system, which as I have managed to understand, it was broken due to a small crash on that side, which resulted in removal of its tube and cables (they were blocked from the owner before me)...could this have anything to do with this?

 

[Dec]

Every thermostat is designed not to open until whatever temperature is needed, in your case 87°c, if the thermostat didn’t open then the car would over heat.

Is the cabin heater air is hot as it should be after a 10 minutes drive? Maybe the temperature gauge is broken and the needle can’t get past 60°c, could that be possible I wonder.

I don’t know about the pre-heating system but under cooling is always the thermostat opening too early or the wrong temperature rating.

Dec

 

[ardisulo]

After about 10 minutes drive I get warm air but not that hot. I have to drive for 30 min city drive to get the car temp better. And almost 40 min city drive for the engine temperature to go to 80. But it is strange to me that when I enter the highway the temperature drops.
I dont think it has something to do with the temp gauge, as I have seen it rise up to 90 Celsius.
Is it possible for the thermostat to open at 60 Celsius?

 

[Dec]

If it’s working properly, then it should not start to open until about 87°c.
I believe the are filled with wax, when the get hot the wax expands and it slowly opens, is there any anti-freeze in the system, 50/50 mix I think?

Dec

 

[ardisulo]

Yes there is a mix of 50/50 G12 Antifreeze (it is rose color).
On Saturday I am going to try the other thermostat model and give a review (as to what I see, it's the only thing left, to try another brand of thermostats).
The make of the Thermostat Motorad is an USA brand I think.
I am posting also the pictures of the BEHR thermostat and Motorad, to show something strange that I have seen.
As you see the BEHR do have the logo and model number printed on it. But on the other side it looks like a serial number removal (and is the same at the old and new one), could it be a fake?
The motorad, except that they have no logo on the outside they have an imprinted sign inside the thermostat...
I am really confused to the fact that how is it possible that two thermostats have the same issue...

BEHR: http://s58.photobucket.com/user/ardisulo/library/BEHR THermostat
Motorad: http://s58.photobucket.com/user/ardisulo/library/Motorad Thermostat

 

[Larkone]

Is the electric fan running when cold? If there is a fault on the sensor circuit causing the fan to run continuously then it will take a long time for the engine to get to temp.

 

[ardisulo]

Well in fact I have owned this car for 3 years and I have only heard the electric fan going on only once (even in summer on hot temperatures), and that may be an issue since the beginning with the car thermostat...and this is very strange. The electric fan goes on only when turning on the air conditioning.
In the following links there are two pictures. The first one is 1 hour after city driving and the temperature didn't hit 80, and the second one is barely reaching to 80 degrees for about ~30 min later...it is really strange...
Anyway tomorrow I will be testing the new thermostat and let you know.
If there are any new ideas please let me know!
Thank you all for helping

First: 20161118_082357_zpsp5sk2igj.jpg Photo by ardisulo | Photobucket
Second: 20161118_084647_zps7lthueyh.jpg Photo by ardisulo | Photobucket

 

[Dec]

Do you have a Mercedes dealer near you?

I have no idea if the are fake or not.

Dec

 

[ardisulo]

No I don't have any near. The only one existing that they do sell Mercedes around here (which they do have e workshop also), I don't think that they are really qualified Mercedes Benz engineers...
In my personal analysis, I think that there are 4 main possible issues:
1. The thermostat BEHR I used are refurbished or re-manufactured (because from the look of it there are signs that suggest they wanted to hide its origin).
2. The Water Pump, pumps water all the time (don't know if this is possible), and forces the thermostat to stay open when the water goes a certain temperature by creating vacuum in a sort of way.
3. The outside temperature sensor (somewhere I read that changing it improved engine operating temperature, which I think it is impossible, but who knows the connection).
4. Maybe it does need bleeding...even though I opened the coolant cap three times when it reached 87 degrees (even though as I recall this car has a self bleeding system).

Right now I am totally out of ideas...Something so simple and yet difficult to diagnose...

 

[Yugguy]

Get a genuine MB thermostat, they're not pricy....

 

[Dec]

Must be something wrong with the thermostat you have, the thermostats just shouldn’t be opening until the coolant gets above 80°c the water pump and the temperature sensor couldn’t cause the thermostat to open before it gets to its correct rated temperature. I think it would over heat if the bleeding wasn’t done right… must be the thermostats opening too early.

Dec

 

[ardisulo]

This is exactly what I think...and I think that the reason I have been having the same problem over and over again is that I used the same thermostat bought in the same shop (probably because they are kind of refurbished or re-manufactured and faulty or not optimal, depending on storage place etc...)
Tomorrow I will try another brand of thermostat and let you all know how this is going. I would feel very frustrated if the shop were I bought BEHR Thermostat, are actually fake (which it wouldn't surprise me because nobody does regular quality checks)...

 

[ardisulo]

So I replaced the thermostat today with a OEM quality which said that "Exceeded the OEM quality standards"...Motorad Brand...
The car changed completely. The temperature gauge rises fast up to 60 degrees and a little bit slower on 80 and it stays there (except when you are driving at 80km/h it goes to ~75 degrees and rises to 80 or ~85)...
Basically from what I am understanding is that in Europe, or at least for the products imported in the Balkans (exactly in Albania, where I live), the thermostats and many auto parts that are imported, are mostly refurbished product or china origin.
I didn't try driving a long road but tomorrow I am gonna do a 100km trip so I am keeping an eye to the thermostat gauge and see how it will behave, and give tomorrow a final review and put the post as solved.
Thank you all for your ideas and help. Really appreciated!

 

[mbenz1]

So I replaced the thermostat today with a OEM quality which said that "Exceeded the OEM quality standards"...Motorad Brand...
The car changed completely. The temperature gauge rises fast up to 60 degrees and a little bit slower on 80 and it stays there (except when you are driving at 80km/h it goes to ~75 degrees and rises to 80 or ~85)...
Basically from what I am understanding is that in Europe, or at least for the products imported in the Balkans (exactly in Albania, where I live), the thermostats and many auto parts that are imported, are mostly refurbished product or china origin.
I didn't try driving a long road but tomorrow I am gonna do a 100km trip so I am keeping an eye to the thermostat gauge and see how it will behave, and give tomorrow a final review and put the post as solved.
Thank you all for your ideas and help. Really appreciated!

I had similar issue in my C220 CDI as on the motorway the temperature would drop down to about 70C from 90C. Changed thermostat with genuine MB part and no issues on the motorway since. It also warms up quicker as well now.

Sent from my GT-I9505 using MBClub UK

 

[ardisulo]

So yesterday was maybe the best day my w202 has had in 3 years...
I did the 100 km trip and the car managed great. The temperature gauge stayed at ~78 degrees and when I hit 90km/h it went to 80 degrees. The fuel consumption was better than I imagined.
When I was driving in the city it went to 87 degrees and after that when I parked I opened the hood to see that for the second time in three years the engine fan was working.:bannana::bannana::bannana:
Well I cant thank you all enough for your help, because as I have seen most of the time we have to diagnose by ourselves the issues with our cars.
Lesson learned...the products that are sold at the auto-parts shop here are low quality, and next time I will buy only genuine MB products (the difference in price was about 10$).