190D running temperature, thermostats, electric clutch fan questions? - PeachParts Mercedes-Benz Forum

ah-kay · #1 06-10-2010, 01:22 PM

Any idea what is the running temperature of a 190D? Mine is always at around 100C. I am not sure whether the electric clutch fan cuts in or not. I know the fan works as I gound the connector at the thermostat switch ( on top of engine block ) and the fan kicks in.

Questions:

1) Would overheating damage the head on the 190D, similar to the infamous #14 head?
2) What is the cut in temperature of the thermostat switch on top of the engine block, 100C, 105C?
3) There is a thermostat switch on the left side of the engine, half way down the block, any idea what is that for?

Any info is appreciated.

vtmbz · #2 06-10-2010, 01:38 PM

My first 190 didnt ever kick in; but my new one kicks on at about 110. It drops to about 90 afterwards. Contrary to the FSM, you dont hear it, but the fan turns much faster.
The front sensor on mine is a 100c; the second sensor under the intake is for the glow plug relay I THINK. I have the electromagnetic clutch btw.

I heated up my first 190 by idling it too long; it got to 120 before I caught it.
I drove away and it cooled right down without damage except for hardening some seals. later I found that all the black paint had flaked off the bottom of the block so I suspect I caught it just in time.

ah-kay · #3 06-10-2010, 01:53 PM

I think I also have the electromagnetic clutch fan. The fan turns when 12V is applied to the coil behind the fan, similar to how the compressor clutch works. I have not seen it works even though I stop the car and lift the hood when the temp creeps up to 100-105C.

I am interested in the left hand side one ( half way down the block ) as I want to use it for Afterglow. The 300SDL has a 50C switch in similar location.

Thanks.

vtmbz · #4 06-10-2010, 04:02 PM

I just checked under the hood. As I recall, the front temp sensor above the radiator hose controls the coolant fan, and in my case, has something to do with controlling the a/c if the engine gets too hot. It has three prongs and four wires: the upper two have two wires on one prong and one wire on the other. Lower prong has one wire.

On the block are two sensors, one helps time the glow plugs (I think its your left one) because in cold weather the glow plug light stays on longer than in hot weather. And I think the sensor between intake 2 and 3 controls the temp gauge- this you can confirm by disconnecting at temp.

The big problem with an afterglow situation would be replacing blown out glow plugs; they are not replaceable without removing the intake, and that is a very arduous process.

ah-kay · #5 06-10-2010, 05:02 PM

My 190D is an older model, 1984, and the thermostat switch on top of the engine block has only 1 prong to control the electromagnetic fan. Yours is a later model as MB uses a 3 prong switch. The 2 prongs will conduct when it is at temperature to turn on the fan. The single prong cuts off the A/C.

You are right that in the engine block there is a thermostat which is used to show the temperature at the temp gauge. The last one may be to control the glow plug relay, I am not sure. I want to make use of it if it is a 50C temperature switch. When at 50C or higher the afterglow circuit will not come in. When it is cold then it will glow for the whole 45sec duration or there about. Using the 50C switch ( if it exists on my 190D ) will extend the glow plug life. I did this to my 300SDL and it seems to be OK and it runs so much smoother during cold morning. It is a PITA to replace GP in any car.