Parts Catalog Accessories Catalog Tech Info Tech Forums
  Search our site:    
 Cart  | Project List | Order Status | Help    

Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 07-11-2002, 04:41 PM
Registered User
Join Date: Jun 2002
Location: Monrovia, CA
Posts: 490
300E - Coolant Temp Sensor: Where is it?

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.



Last edited by Phalcon51; 07-11-2002 at 05:24 PM.
Reply With Quote
Old 07-11-2002, 04:46 PM
Registered User
Join Date: Feb 2002
Location: St. Louis, MO
Posts: 340
Me too, but on '97 E320

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.
Reply With Quote
Old 07-11-2002, 06:33 PM
JimF's Avatar
'94 S500: only 793 sold!
Join Date: Mar 2001
Location: San Diego, CA
Posts: 1,924
Check this picture. . .

If you want a 'pro' version, check my page!
Regards . . . . JimF
'94 S500 Cpe

Visit my Mercedes Web Page
Reply With Quote
Old 07-12-2002, 12:09 AM
Registered User
Join Date: Jun 2002
Location: Monrovia, CA
Posts: 490

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?


Last edited by Phalcon51; 07-12-2002 at 01:03 AM.
Reply With Quote
Old 07-12-2002, 12:26 AM
pmizell's Avatar
Benz Zealot
Join Date: Jun 2001
Location: Houston, Texas
Posts: 838
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,


'91 300E, 215K miles
Reply With Quote
Old 07-12-2002, 12:46 AM
Mike Murrell's Avatar
Registered User
Join Date: Feb 2000
Posts: 2,141

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:

1986 300E coolant temp. sensor!
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC

James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.

Liberty Firearms Training - After years of trying to regulate California criminals with a never ending stream of gun control laws they have still not given up with the belief that if they make something a crime that criminals will miraculously start obeying the law.
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 05:00 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page