WhathaveIdone

I have a new to me, 2013 e350, well cared for, and no CEL. 85,000 miles.
Everyday I get a 'Check Coolant Level; message. I have checked the level and it is correct.
When driving recently, and sitting in traffic, I noticed the coolant temperature gauge rises quickly to 120+. I didn't hear the radiator fan come on.
I immediaely shut down the engine and sat to allow it to cool. Upon starting and moving, it immediately dropped to 90+ which is normal.
When I am driving the temp stays consistent.around 90-95C. I am now starting to hear the radiator fan slowly start and increase rpm when sitting at a light.
It is maintaining the temperature to less than 100. Again, it cools quickly once I am underway and ambent temperatures are flowing throught radiatoor (13C)
I suspect the temperature sensor in the thermostat is failing. With no CEL or fault codes showing in the Star Diagnostics, is this a reasonable diagnosis?

bmwpowere36m3

Sounds similar to this: https://mbworld.org/forums/e-class-w...oss-power.html

Temp gauge shoots up and after restart or idling the temp comes back down. Though I find the low-coolant level message of interest... when do you get the message, before you start the car (cold), while driving or after shutdown. The fan is controlled by the engine management module (ECU) and the coolant temp sensor is not the only input, it also relies on climate control and A/C pressure, could be others as well.

You also would need to consider whether that same sensor is what feeds the gauge, which if it appears to be working... why wouldn't it work for the ECU input to control fan.

WhathaveIdone

Yes, the "Check Coolant Level" comes on when starting and will stay on. Coolant reservior is up to the full line.
The Coolant temp gauge at idle, with fan on, will eventually rise to 110, the fall quickly, then rise again, etc.
I am inclided to replace the thermostat and it also contains the temperature sensor.
Of course, it could be something else.

KEY08

you should be getting a CEL and an appropriate code if the thermostat is bad. I agree that the fans are not engaging properly or sporadically.

bmwpowere36m3

Is that with A/C on? Ambient temps? Does the fan speed change as the temp increases? I'm surprised it would get that high with the fan ON at idle, maybe with A/C ON, heat soaked, stop 'n go.

How quickly does the temp rise? Do you have an IR gun to check the thermostat housing for actual temp? What if you set cabin heat to full HOT, will the temp continue to rise and fall?

The fan is controlled by the ECU, so having a good scanner might shed light on what's going on. I'm still wondering about the low-coolant light... maybe a red herring. Does the level in the tank change between cold, before starting, during start, after its warmed up?

WhathaveIdone

The AC is off. Ambient temps around 55F. The fan speed does increase gradually and the temp remains stationary for a while then quickly spikes up to 110 with the fan on full speed, then the temp will drop and spike again. This is all while idling. I shut the car down, and the fan was at full speed, and continued for another 5 minutes.
I did start the cabin heating a while back in hopes of lowering the temperature. The heater works fine, but the temps continued up to 120C when I shut the engine off and parked.
I do have a STAR Diagnostic tool which shows no fault codes.
I suspect the coolant level sensor in the reservoir is faulty, so have another new one ready to install.
But before I do that, was thinking of replacing the thermostat assembly as well.
There also is a temperature sensor in the thermostat and another on the left rear of the engine. Given the car is 8 yearts old, it might be getting ahead of the failure curve.

WhathaveIdone

I have checked the level in the coolant reservoir before and after and see no change, but have not checked it while the engine was running.

bmwpowere36m3

*edit*

I couldn't help myself and looked thru WIS a little... the thermostat housing for the M276 only appears to have an electrical connection for thermostat control (wax motor). I do not see a temp sensor as part of the thermostat housing. There's a temp sensor somewhere towards the rear of the engine (based simply on ground splice for connection).

Additionally the low-coolant sensor is not replaceable per WIS, entire reservoir needs to be. I'll post some info later.

I'll stand to be corrected.

rapidoxidation

Is your upper radiator hose still hard after a night's cooling off? Tomorrow morning, when the engine is stone cold, open up your coolant expansion tank cap. Got pressure?

WhathaveIdone

Good question. Will check the upper rad hose for pressure after sitting over night. I do notice a pressure release when I remove the cap the next morning.

rapidoxidation

Try this:
After driving, and after the engine has cooled off a bit (but not a lot) release the pressure in the coolant system and seal it back up tight. The next morning the upper hose should be collapsed due to contraction - unless there's somewhere for air to get back into the system (I'll not say the phrase *ead *asket yet).

bmwpowere36m3

I've attached some docs of interest... I also wonder if the low-coolant message has any secondary effects and may be worth correcting first and then proceeding further. Another obvious thing to check would be any debris, garbage bags, etc... either between fan housing and radiator or in-front of the condenser.

*edit*
Only applicable as noted by konigstiger for code 5U3

The air shutter mechanism is of interest as well... what if the shutters weren't operating correctly. Their vacuum operated, does the ECU monitor their position (and this trouble codes or lack of)?

KEY08

I had no idea these cars had air shutters. My Jeep is the only car I own that I thought had them.

konigstiger

Only if data card lists code 5U3 radiator grille w/adaptive closing function.

WhathaveIdone

Thanks for all the great suggestions. Working on them today.

I am confused on a part number and location for the B11/4 engine temperature sensor. There is conflicting fitament information for this part.
My engine, M276.952 (2013 E350 Base W212) shows

a temperature sensor (see diagram at B11/4) same as the M272 (W211). Is this correct? The part number as best as I can tell is 000-905-61-02 but most sites say it does not fit my model.
Anybody have lock identifying the part number?

WhathaveIdone

WhathaveIdone

bmwpowere36m3

I'd confirm with your VIN, but 276.952 engine. The number may be superseded as my copy of EPC is 2019.

WhathaveIdone

Thanks. This is best illustration I have seen.

S-Prihadi

Is this issue solved ? I am very curios.

Thanks to BMW for post no 12 https://mbworld.org/forums/e-class-w...ml#post8262261 ,
I now realized my knocked off ebay bought EPC/WIS of 2018 , is missing lots of documents on the WIS side. I can't find these 2 documents :
GF20.40-P-1000A Cooling-air flow, basic function
GF20.10-P-1001A Coolant thermostat, basic function << this document showed an important link , which is the GF20.10-P-2004A as attached.

So thanks to Uncle Google, I now have GF20.10-P-2004A
GF20.10-P-2004A Coolant thermostat heating element, basic function this may help OP troubleshoot his problem if it is not solved yet.

This document also answered my questions to why it seems my engine is running "hot" as in : 105 C being normal.
I know about this MAP/ECU controlled thermostat thingy..... as I shared here : https://mbworld.org/forums/e-class-w...at-action.html
But I never realized this crucial information on how my MAP thermostat basic design is :

=================
Open position (radiator mode)
Coolant temperature at 118 °C
The coolant thermostat is fully opened and coolant flows through the radiator
=================

Holy cow, thermostat only fully open at 118 Celsius !!!!
I was thinking.... if purely melting a wax via heater is how the MAP/ECU thermostat is controlled, meaning ECU can only open the thermostat early if required,
that means its mechanical* side ( *the wax ) would be designed to open/melt much hotter than a conventional pure mechanical thermostat which usually is 83C - 93C
The question is , would the ECU produce a CEL/Codes if ever the heater failed NOT in open circuit ?
If no CEL/Codes , the 118C is probably when the wax finally will melt and fully open the thermostat mechanically and 120C coolant temperature is probably the result.

==============================
The actuation of the coolant thermostat heating element is realized via a pulse width modulated signal
with a frequency of 141 Hz from the combustion engine control unit. The power supply occurs via "circuit 87 M".
==============================

WhathaveIdone

As of today, one week after repairs including replacing thermostat, coolant tank, radiator, lines, and flushing the cooling system, and transmission 3 times, the overheating is resolved.
The temperature runs at a constant 95C. The transmission shifts between 1 and 2, and 2 and 3 are still a bit harsh, but can be moderated with modest acceleration. I am showing no codes.
I am told I could get another 20-30k miles on this 722.9 transmission before rebuild or replacement. It depends on the extent of the damage to the friction discs when exposed to engine coolant.
Thanks to all for the helpful suggestions.

S-Prihadi

bmwpowere36m3

The document you linked with the Coolant thermostat heating element doesn't "look" like the thermostat/housing on M272, M273 or M276 (not sure on the M278 or M157). It also contradicts the information in the Coolant thermostat which states: At a coolant temperature above 93 °C, the thermostat is fully opened and the engine has reached its operating temperature. The coolant fully flows through the radiator and all coolant circuits

Hmm... but I get what your asking about the wax element melting temp and how the heater plays into that scheme.

bmwpowere36m3

Here's an interesting animation:



generic thermostat map

It appears the heater is used to "anticipate" higher loads and lower operating temps when desired. It also benefits from quicker response and tighter control of coolant temps. Ultimately I suspect its all emissions related, not necessarily reliability or performance.

S-Prihadi

I learn to absorb information from the WIS in a careful fashion.
Never trust 100% pictures showed for illustration. Sometime WIS does state that the illustration is from X car model with Y engine, sometime WIS showed illustration of a component without stating from which engine it comes from.

I give you an example of poor spacing of different information in GF20-10-P-1001A which may confuse a reader. I will separate the information into Zones.
Zone A in green box speaks of pure mechanical thermostat only.
So the information stated as : At a coolant temperature above 93 °C, the thermostat is fully opened and the engine has reached its operating temperature. The coolant fully flows through the radiator and all coolant circuits
belongs ONLY to the mechanical thermostat, zone A.So it does not contradict.






Zone B in blue box and Zone C in red box, must be read along with separate GF20.10-P-2004A Coolant thermostat heating element, basic function , which showed the funny boxy thermostat,
but the irony is Zone B already showed a thermostat with heater element... LOL.
If only GF20.10-P-2004A uses the same thermostat of zone B and with a little creative see-thru for its heating element, a speed reader won't misread.





Some other small details....

The original source of all these documents are in German language I am sure.
There are many documents in WIS, even for me a non native English language speaker, I can detect some information are pure literal translation German to English and does not read right in automotive/mechanical terms.

Actually, lately as I work more on the car and read more WIS, I am not surprised at how WIS can be confusing . The amount of information on the WIS and EPC is massive and putting them together in multiple languages is no easy task.
When document content writers are engineers, but document organizer and/or illustration editor and the German to English translators are not engineers/petrol head, things can go a bit confusing.

Below excerpt from GF20.10-P-1001A I am sure is not translated into English by an engineer or petrol head translator.
The heating element is actuated by the combustion engine control unit
and influences the expansion of the wax expansion element.

In the German version doc, they call engine as Verbrennungsmotor so a literal translation is combustion engine
I don't speak German at all, I am simply looking at pattern of the English version of the WIS odd vocabulary for someone like me a non native English speaker.
Any US or British doing the same explanation will simply write : The heating element is actuated/controlled by the engine control unit
because we all know , WIS is for automotive technician/workshop and we call engine as simply engine/motor, be it gasoline spark ignited engine and diesel compression ignited engine.

Now the excerpt : influences the expansion of the wax expansion element.
Won't you think above is a wrong technical description of what will happen to the wax when heated ?
Above does not describe that melting the wax allows the valve to actually move/open, it must have been lost while in German to English translation where expansion should have meant as opening.

Now we take a British guy from Hanynes Publishing explaining the same thing for the wax cavity :
https://haynes.com/en-us/tips-tutori...hat-does-it-do
These thermostats use a chamber that contains a wax pellet, which melts at between 175 and 200 degrees, releasing a spring. This operates a rod that then opens a valve .... yada yada

I seen the video and the Mahle documents, in fact I have posted the link if you want to see ECU/MAP controlled thermostat in action on my engine which is using the zone B ECU controlled thermostat..... let me post it again :
https://mbworld.org/forums/e-class-w...at-action.html

When I look at anything temperature and pressure related for cooling and lubrication, I tend to be extra attentive and cautious as I like to add what-if scenario in my preventive maintenance plan.
I am just so worried, if 118 Celsius being a failed thermostat's heater condition/scenario for full flow to radiator to happen mechanically by melting the wax on its on without heater assist,........
that is too narrow a margin for cars in the tropics with 32-35C ambient daytime temp all year round with bumper to bumper traffic which surrounding temperature on the street for radiator intake can actually be like 40C.
If the coolant is not a proper 50/50 and the radiator reservoir pressure cap is not a good 1.4BAR integrity and then Murphy Law strikes... hhmm sad, very sad for the car owner as the coolant
estimated 138C boiling point can't be achieved as safety zone.

I hope this 138C boiling point is accurate or at least we can get 134C, I took it from the literature below :
https://durathermfluids.com/pdf/tech...ling-point.pdf




Now the temperature gauge display on my car makes more sense, all these also answered why there were no alarm warning, when I had for 10+ seconds of 120C coolant temp during some fun-at-track session last year.
Basically 120C is not yet a "HOT" condition, as the red zone starts above 120C. Smart the MB engineers are, 100C is on purpose not marked in numeric but simply a line only, otherwise old timers will freak out seeing 100C in normal driving


Sorry for the long write..... but it is fun for learning.