Coolant level sensor - Mercedes-Benz Forum

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 13 (permalink) Old 02-25-2008, 11:12 AM Thread Starter
BenzWorld Member
 
Date registered: Oct 2005
Vehicle: 1997 SLK 230K
Location: Ankara, Turkey
Posts: 68
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Question Coolant level sensor

Hi, I just changed the thermostat and while driving the coolant level light came on yesterday. Checked, correct, the coolant dropped a little during the repair, but I then topped the coolant and the light is still on ??

how does the coolant level sensor work? I searched the forums but only found some answers on bmw forums which may not apply to mercs I think.
leventguner is offline  
Sponsored Links
Advertisement
 
post #2 of 13 (permalink) Old 02-25-2008, 11:45 AM
BenzWorld Elite
 
Bruce R.'s Avatar
 
Date registered: Aug 2002
Vehicle: 2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
Location: Near Washington, DC
Posts: 14,926
Mentioned: 0 Post(s)
Quoted: 41 Post(s)
Check the water level in you windshield washer tank as well. For some reason "they" decided that both tanks should go through the same warning system...

"Negotiating with Obama is like playing chess with a pigeon, the pigeon knocks over all the pieces, on the board and then struts around like it won the game."
Vladimir Putin

"They have gun control in Cuba. They have universal health care in Cuba. So why do they want to come here?"
Paul Harvey 8/31/94


"The only people who have quick answers don't have the responsibility of making the decisions."
Justice Clarence Thomas
Bruce R. is offline  
post #3 of 13 (permalink) Old 02-25-2008, 12:57 PM Thread Starter
BenzWorld Member
 
Date registered: Oct 2005
Vehicle: 1997 SLK 230K
Location: Ankara, Turkey
Posts: 68
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
I filled that up too, no change.. since it fired because of low coolant and stayed on after it seems unlikely to me that the sensor failed.. but I cant be sure..
leventguner is offline  
post #4 of 13 (permalink) Old 02-25-2008, 01:23 PM
BenzWorld Elite
 
Bruce R.'s Avatar
 
Date registered: Aug 2002
Vehicle: 2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
Location: Near Washington, DC
Posts: 14,926
Mentioned: 0 Post(s)
Quoted: 41 Post(s)
OK, the radiator tank is full, the washer tank is full, and the float in the fill neck is free to move, right?
The next likely thing is the sensor itself.

"Negotiating with Obama is like playing chess with a pigeon, the pigeon knocks over all the pieces, on the board and then struts around like it won the game."
Vladimir Putin

"They have gun control in Cuba. They have universal health care in Cuba. So why do they want to come here?"
Paul Harvey 8/31/94


"The only people who have quick answers don't have the responsibility of making the decisions."
Justice Clarence Thomas
Bruce R. is offline  
post #5 of 13 (permalink) Old 02-25-2008, 01:57 PM Thread Starter
BenzWorld Member
 
Date registered: Oct 2005
Vehicle: 1997 SLK 230K
Location: Ankara, Turkey
Posts: 68
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
the float, I am not sure about that, I noticed a plus sign while filling but I don't see it always.. how does the float and the sensor work together?
leventguner is offline  
post #6 of 13 (permalink) Old 02-25-2008, 02:29 PM Thread Starter
BenzWorld Member
 
Date registered: Oct 2005
Vehicle: 1997 SLK 230K
Location: Ankara, Turkey
Posts: 68
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Lightbulb

ok, I searched the posts about the float, I will try to pull it up with a screwdriver to see if it moves freely inside.
leventguner is offline  
post #7 of 13 (permalink) Old 02-25-2008, 09:09 PM
BenzWorld Extremist
 
DickB's Avatar
 
Date registered: Dec 2002
Vehicle: 1999 SLK 230
Location: Minnesota
Posts: 937
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Bruce R. View Post
Check the water level in you windshield washer tank as well. For some reason "they" decided that both tanks should go through the same warning system...
Not the case on my '99. There are separate indicators for each. It is true that the two sensors are wired in series, but they also each have separate series/parallel resistors in them, so that the instrument cluster electronics can tell which sensor is triggered. In the diagram, S41 turns on E11 (coolant) and S42 turns on E13 (washer).
Attached Thumbnails
Click image for larger version

Name:	sensors.jpg
Views:	2461
Size:	52.4 KB
ID:	164628   Click image for larger version

Name:	coollantsensor.jpg
Views:	4400
Size:	57.5 KB
ID:	164629  
DickB is offline  
post #8 of 13 (permalink) Old 02-26-2008, 04:46 AM Thread Starter
BenzWorld Member
 
Date registered: Oct 2005
Vehicle: 1997 SLK 230K
Location: Ankara, Turkey
Posts: 68
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Smile

Thanks to both of you, I pulled the float a little bit and now the light is off. It is just under the surface of the fluid and I assume it is ok.
leventguner is offline  
post #9 of 13 (permalink) Old 02-26-2008, 09:16 AM
BenzWorld Elite
 
Bruce R.'s Avatar
 
Date registered: Aug 2002
Vehicle: 2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
Location: Near Washington, DC
Posts: 14,926
Mentioned: 0 Post(s)
Quoted: 41 Post(s)
Quote:
Originally Posted by DickB View Post
Not the case on my '99. There are separate indicators for each. It is true that the two sensors are wired in series, but they also each have separate series/parallel resistors in them, so that the instrument cluster electronics can tell which sensor is triggered. In the diagram, S41 turns on E11 (coolant) and S42 turns on E13 (washer).
OK, I'm sure you are correct, the '32 may be slightly different, and things have obviously changed.
My radiator fill light came on for no apparent reason with the tank "full" and the washer tank low. I added fluid to the washer tank as has been described in some other posts that I recalled and the light has not come on again.... The washer needed almost a gallon of fluid to bring it up to full... !

Thanks for the schematic, it helps a lot.

"Negotiating with Obama is like playing chess with a pigeon, the pigeon knocks over all the pieces, on the board and then struts around like it won the game."
Vladimir Putin

"They have gun control in Cuba. They have universal health care in Cuba. So why do they want to come here?"
Paul Harvey 8/31/94


"The only people who have quick answers don't have the responsibility of making the decisions."
Justice Clarence Thomas
Bruce R. is offline  
post #10 of 13 (permalink) Old 02-26-2008, 01:52 PM
BenzWorld Junior Member
 
Date registered: Aug 2002
Posts: 8
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
On my 99 SLK230, I had the same problem. After the dealer replaced the coolant level sensor two or three times under warranty, they filled the windshield washer tank and the problem disappeared. So, maybe some cars are different or maybe things changed since my car was built but that was my experience.
pfphipps is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Roadster Forums > R170 SLK-Class

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











  • Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
     
    Thread Tools
    Show Printable Version Show Printable Version
    Email this Page Email this Page
    Display Modes
    Linear Mode Linear Mode


    Forum Jump

    Similar Threads
    Topic Author Forum Replies Last Post
    1993 600SEL coolant level sensor, where is it?? foxmuldor W140 S-Class 4 12-29-2010 05:39 AM
    Coolant Level Sensor 01E320 Benzo DJ W210 E-Class 3 09-29-2008 04:51 PM
    Coolant Level COmes on Creative85 W210 E-Class 0 12-04-2006 09:59 PM
    Coolant level sensor warning YellowSLK230 R170 SLK-Class 9 11-03-2004 08:37 AM
    Coolant Level anant369 R170 SLK-Class 2 01-14-2003 04:23 PM

    Posting Rules  
    You may post new threads
    You may 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

     

    Title goes here

    close
    video goes here
    description goes here. Read Full Story
    For the best viewing experience please update your browser to Google Chrome