I need to find my coolant temp sensor on my '86 300E, the one that triggers the aux. fan (I want to bridge it with a resistor to make it come on at a lower temp) - would someone please tell me where it is and what it looks like? What color are the wires going to it or what color is the plastic part of it?

Also, is there any accurate way to test it without special tools? It seems to be triggering the fan a bit late - about 110C by the dash gauge.

Thanks,

Gary

Hard to get a definitive answer on this. One responder said rear of block. Aanother said front on/near water pump. I can't see anything but the one for the temperature indicator. i'm looking for the one that the engine management system uses. Thanks.

If you want a 'pro' version, check my page!

__________________
Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page

JimF,

Thanks for the pic. In that location, I've got a similar looking device, except that it has one 2-wire plug and a 1-wire plug. Any idea what the extra lead is for? Can I still bridge the 2-wire connector with a resistor to effect a lower aux. fan trigger point?

Gary

The coolant temp sensor has moved around on the M103 engine, depending on model year. On your '86 model, it is located at the rear of the head, last sensor before you hit the firewall and it looks like this:



Have a nice day,

~Paul

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'91 300E, 215K miles

Paul:

According to an old post here, there are actually THREE coolant temp sensors. I believe the one that JimF circled above in the photo is for controlling aux. fans. Please see the following thread:

http://www.peachparts.com/shopforum/showthread.php?threadid=7560&highlight=coolant+temp+sensor

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"