W204 M271 EVO thermostat sensor

[gordon cerar]

Gday all ,gonna have a whinge about my 2012 C250 coupe with a 1.8 litre turbo motor . My gripe being is i replaced the thermostat housing.Prior to changing thermostat, temp was consistently 75c and water circulating thru radiator . Now temp quickly climbs past 90c and radiator is cold.It is obvious that the thermostat is not fully open. Now this thermostat has 2 electrical connections on it. On the side is the temp sender unit. In the guts , you have a probe that centers into the middle of the actual thermostat. I understand that thermostat is electrically assisted. (1) So i am under the assumption that this probe generates heat to enable the thermostat to open when under power 12v. (2) If it does need power to energise the probe , one would assume that there must be a ballast resistor / relay that controls the voltage ? There's a **** load of relays in the engine bay ,don't know where to start looking ??? Wiring diagram might be of use if i can find one ! Oh well cheers from Gordo !

 

[LostKiwi]

Hi and welcome.
Two quick questions:
1. Did you fit genuine parts?
2. Did the thermostat function at all previously or was it jammed?

 

[mioba]

Sounds like a foobarred stat

 

[LostKiwi]

Sounds like a foobarred stat

That's my thinking.

 

[gordon cerar]

Never had temp issues prior to replacing thermo housing due to leak. Secondly , new thermostat housing is non gen part. Have tested unit for operation prior to installing unit

 

[gordon cerar]

Now the plot thickens ! Have been able to scan the car for codes. 1st code comes up as PO53A00 , output for heating element of the vent line crankcase has electrical fault or circuit open . Being a heating element,one assumes it's has its own relay for voltage load ? Now vent line to crankcase ? Correct me if i'm wrong, but there are two vent lines,one on tappet cover to intake pipe and one near l/h engine mount to boost side of intake manifold ?? Next code is PO59700 . Thermostat heater control circuit / open ?? All wiring seems to be plugged in ? I am getting 12 . 2 volts power to sensor probe in thermostat housing plug . Now the last code to come up is P22900 which is ambient pressure sensor has a shot circuit to positive . Now i assume that means that the MAP sensor is having issues / faults ?? Time for more research ! Cheers to all ! Gordo

 

[LostKiwi]

I suspect you're being led down a rabbit hole.

What code reader did you use to read codes?

If it's not an MB specific one the descriptions could be misleading.

That said the second code P0597-00 would suggest your thermostat is no good.

It wouldn't be the first time a non-genuine thermostat hasn't worked.
Personally I'd use either genuine or (at a push) Wahler.

On the basis of this issue only appearing after the thermostat was replaced I'd start there rather than look for another fault that probably isn't there.

 

[malcolm E53 AMG]

^ agree with the above regarding fitting the genuine part there have been a few issues on here regarding after market thermostats

 

[ajlsl600]

Christ,, a std statt has worked well for ? 50 yr! Or more.changed for electronic headache . no doubt organised not to recognise yr after market product and sold as assly to cost you more.make finding a non dealer part harder and create more waste. When I need to change mine I will spend a week trying to mill out my own housing and if at all possible fit something I can change for a tenner.

Think yr replacin yr statt again ! Hope u geet yr cash back.

 

[ajlsl600]

There are two kinds of tech today
1 does a job you used to have to do in such a way as you can forget about it.( extremely rare )
2nd tech that turns you into a permanent consumer ( by far the most prevalent )
I try very hard to avoid the 2nd and never rush for most tech let some other canary do the R&D is my prefered choice.

 

[LostKiwi]

Christ,, a std statt has worked well for ? 50 yr! Or more.changed for electronic headache . no doubt organised not to recognise yr after market product and sold as assly to cost you more.make finding a non dealer part harder and create more waste. When I need to change mine I will spend a week trying to mill out my own housing and if at all possible fit something I can change for a tenner.

Think yr replacin yr statt again ! Hope u geet yr cash back.

The idea of the electronic thermostat is to increase engine temperature when on part throttle to improve economy but cool the engine more on full throttle to aid power.

Pretty sure a similar system wouldn't be difficult to arrange mechanically....

 

[ajlsl600]

The idea of the electronic thermostat is to increase engine temperature when on part throttle to improve economy but cool the engine more on full throttle to aid power.

Pretty sure a similar system wouldn't be difficult to arrange mechanically....

Wot happened to keep it simple.?

 

[LostKiwi]

Wot happened to keep it simple.?

Where's the profit in that?

 

[ajlsl600]

Xactly.but I like to choose how/when I spend my cash,not have some car maker determine that for me...

 

[gordon cerar]

Now an update on the this debacle . i replaced thermostat because of a leak. Replaced item with generic part. Bleed coolant system. Start engine ,within few minutes ,temp up 90 deg, which is normal by MB . No water was circulating thru the radiator,even after 20 minutes .Even more bizarre , no check engine light ! So bring out the G Scan and she spat out those codes. PO53A00 turns out the be the breather pipe valve that connects into the 1st intake pipe just in front of the turbo . Cause was didn't have intake breather valve wire connected from filter box to turbo. Turns out that Code P22900 is a sensor on same intake pipe just in front of the thermostat housing . Code PO59700 turns out to be a sensor for the thermostat , hence no water thru radiator . Out of curiosity , i delete these codes out of frustration , low and behold , the radiator is now circulating hot water ! Problem solved , i think ? So why wouldn't the ECU allow signals from / for the new part , until i deleted those codes . Modern electrics grrrrrrr ! Now to worry about oil leaks coming from the front of the engine ! Cheers