Folks,
I find it amazing how it seems that folks in different parts of the country are working on similar items at the same time.....lol

I have my cooling system apart this AM......had purchased a new water pump sometime back (Februaryish).....had been thinking that I had a bearing noise.....not a temperature problem.....gathered up enough stuff to do several things while I had the engine partly disassembled.....

The attached photo is my '85 300D (Federal) Thermostat Housing......you will note that there are 2 temperature sensors.....one should be the 100*C Aux Fan cut in switch, and the other should be the 40*C Climate Control blocking switch (does not allow the Klima Control to work below 40*C so you get no cool air on a frosty morning)......



I had thought that the larger one in the center was the 100*C Aux Fan....but I was wrong, it appears that the Center one is the 40*C Klima Blocker....and the smaller one on the right (inlet to housing) id the 100*C one for the Aux Fan......at least that's what I gather from the temperature rating on the center one....

I took this apart in order to change out that little 2" piece of hose that goes between the water pump and the thermostat housing......just mentioning this for those who may have forgotten to peek at that one on occasion.....

There is also a current thread relating to Citric Acid flushing of the cooling system....I had been seeking some of that Citric Acid to flush my system while I did this job.....however, I found very little scale and/or corrosion.....so unless my radiator has a problem, I'm good.....when I refill with fresh coolant, I use distilled water, because my well water has a lot of calcium in it.....

SB

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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

it makes sense that the one on the right is the 100C switch, it's in the water jacket to the head, the other one is in the cool water return from the radiator...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

It's not in the line from the radiator....it's in the supply to the water pump....that would make it the mixed water from the head and the radiator after the 80*C thermostat....but yes it should be definitely cooler than the water exiting the head, in most cases.........

SB

__________________

Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

oh, I don't think it would matter where they put the sensor for the kilma, it would work anyplace, even under the oil pan, but the sensor for the aux fan needs to know how hot the water in the head is!

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

VS....in the other thread that began relating to the Citric Acid cleaning of the cooling system.....you mention that your car is running at 100*C.....if so your aux fan should be on.....

The reason that I mentioned this in the first place, is.....if you read the AC Klima Shop Manual.....in there you will see the AC block identified as being on the outlet of the head....but in that photo there are 2 sensors there with the other unmentioned....so I had assumed that the solo one that I had there was for the AC System....when I began my little M&R session, I learned otherwise, and was just posting to let others know.....

SB

__________________

Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

my car is an 82 SD, and I don't think there is any sensor for the aux fan there. the fan is not coming on. id does come on with the a/c though.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!