500SEC Boiling when at idling (stand-by) app 600rpm for more than 6-8min - Page 3 - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
post #21 of 92 (permalink) Old 06-24-2019, 11:13 AM
BenzWorld Extremist
 
gogi's Avatar
 
Date registered: Jan 2008
Vehicle: 1991 560sec. 1969 280SL
Location: New Jersey
Posts: 914
Mentioned: 7 Post(s)
Quoted: 238 Post(s)
Quote:
Originally Posted by roadhouse View Post
Quote:
Originally Posted by gogi View Post
Why not just bypass the ac pressure switch at the dryer to test the auxiliary fan motor and at the same time you’ll know if the switch is faulty.
Because what I suggested is easier than having to wrestle with the drier pressure switch. Most times thing are dirty or the connectors are stuck together, and it’s a bitch to separate them.
The plug slides off the tstat sender right away, and all you need is a metal object that fits inside the plug. Presto, you can test the aux fan.
That leaves the pressure switch out of the equation no? If a blade fuse is used to jump the two wires going to P/Switch that also checks the circuit integrity from there.
Also do what you suggest and the whole circuit gets tested and there are no unknowns.
gogi is offline  
Sponsored Links
Advertisement
 
post #22 of 92 (permalink) Old 06-24-2019, 11:38 AM Thread Starter
GT1
BenzWorld Junior Member
 
Date registered: Apr 2019
Vehicle: 2x500SEC Euro early 80s/ 560SEC 88" Euro / Object 500
Location: EUROPE
Posts: 44
Mentioned: 0 Post(s)
Quoted: 15 Post(s)
(Thread Starter)
So now tested.

Direct 12V from some coupling into fan-coupling, fan running like a dream. Tried el-spray and clean all couplings, all connections etc.

Electric fan never start AUTOMATICALLY. Never. Not at 100C , 110C 118C. Not when AC on. Not when air cirulation in car is on.

Checked and cleand alle fuses. OK
Checkes and cleaned all rele. Looks fine. (Not tested functionality though)

So the plug in the picture ( plug female from fuse box name 9622/1 ) which leads down to the fan plug female NEVER have 12V. Measeure constant with fluke during 1hr testing.

so here is what i think.
1) Caput rele. But not sure which.
2) Some sensor not gove the trigger point for this 12V to start at 105C or when AC is running.
3) other?

appriciated. See pics as well
Attached Thumbnails
Click image for larger version

Name:	121212.JPG
Views:	9
Size:	36.4 KB
ID:	2523384   Click image for larger version

Name:	Plug comming from fuse box. Never measure 12V on it in any situation .jpg
Views:	8
Size:	3.01 MB
ID:	2523386  
GT1 is offline  
post #23 of 92 (permalink) Old 06-24-2019, 12:38 PM
BenzWorld Extremist
 
gogi's Avatar
 
Date registered: Jan 2008
Vehicle: 1991 560sec. 1969 280SL
Location: New Jersey
Posts: 914
Mentioned: 7 Post(s)
Quoted: 238 Post(s)
[QUOTE=GT1;17823186]so here is what i think.
Some sensor not gove the trigger point for this 12V to start at 105C or when AC is running.
other?
/QUOTE]
I had a 500sel back many years ago on that engine if you disconnected the two wire coolant temperature sensor on the thermostat housing the auxiliary fan would stay on, that’s how you knew the temp. sensor was bad, yours is not coming on from high engine temp. or high ac system pressure. I think you should locate and swap the auxiliary fan relay with one of the others in the fuse box. Some of them are the same.
Check for 12v at the ac pressure switch. Assuming you have power to the pressure sensor, I think if you disconnect the two wires at the red pressure switch that is on the receiver dryer, and bridge them you may find the fan comes on. If it does come on you will know the that switch/sensor is faulty. There is also a resistor in the circuit somewhere under the master cylinder for that fan.
You need member MLB560SEC for a wiring diagram for that circuit.

Last edited by gogi; 06-24-2019 at 01:04 PM.
gogi is offline  
Sponsored Links
Advertisement
 
post #24 of 92 (permalink) Old 06-24-2019, 12:59 PM Thread Starter
GT1
BenzWorld Junior Member
 
Date registered: Apr 2019
Vehicle: 2x500SEC Euro early 80s/ 560SEC 88" Euro / Object 500
Location: EUROPE
Posts: 44
Mentioned: 0 Post(s)
Quoted: 15 Post(s)
(Thread Starter)
[quote=gogi;17823252]
Quote:
Originally Posted by GT1 View Post
so here is what i think.
Some sensor not gove the trigger point for this 12V to start at 105C or when AC is running.
other?
/QUOTE]

Assuming you have power to the pressure sensor, I think if you disconnect the two wires at the red pressure switch/sensor that is on the receiver dryer, and bridge them you may find the fan comes on. If it does come on you will know the that switch/sensor is faulty. There is also a resistor in the circuit somewhere under the master cylinder for that fan.
You need member MLB560SEC for a wiring diagram for that circuit.

1) The only thing i know i that fan is running when it is energized with 12V. Fan has no noice or any other issues i see, feel og hear. Period.
2) So now we can assume fan is OK so far.
3) So why do i not have the 12Voltage at any stage presented to the fan wire. If i had a diagram i would read it (el engineer) but right now i dont. If anyone can provice appriciated a lot.
4) gogi, thanks for reply. But i dont know location of what you are talking of. Which pressure sensor and what other sensor ? And show location of resistor and i will check it quickly. Please, send pics or dwg and i will understand asap. Thanks again.

HIGHLY APPRICIATED
Best
GT1 is offline  
post #25 of 92 (permalink) Old 06-24-2019, 01:15 PM
BenzWorld Extremist
 
gogi's Avatar
 
Date registered: Jan 2008
Vehicle: 1991 560sec. 1969 280SL
Location: New Jersey
Posts: 914
Mentioned: 7 Post(s)
Quoted: 238 Post(s)
Here is a pic. I believe it’s on the left side under the brake master cylinder.
Attached Images
 
gogi is offline  
post #26 of 92 (permalink) Old 06-24-2019, 01:34 PM Thread Starter
GT1
BenzWorld Junior Member
 
Date registered: Apr 2019
Vehicle: 2x500SEC Euro early 80s/ 560SEC 88" Euro / Object 500
Location: EUROPE
Posts: 44
Mentioned: 0 Post(s)
Quoted: 15 Post(s)
(Thread Starter)
Quote:
Originally Posted by gogi View Post
Here is a pic. I believe itís on the left side under the brake master cylinder.

[QUOTE=gogi;17823252][QUOTE=GT1;17823186]so here is what i think.
Some sensor not gove the trigger point for this 12V to start at 105C or when AC is running.
other?
/QUOTE]


AGREE - A SENSOR ISSUE, BUT WHICH? HELP !

Thaks gogi, and where are you other good guys, i dont wanna buy a bunch of sensor incl work for nothing... lol

Where is this one you reffere to located mate ?

Best
GT1 is offline  
post #27 of 92 (permalink) Old 06-24-2019, 01:36 PM Thread Starter
GT1
BenzWorld Junior Member
 
Date registered: Apr 2019
Vehicle: 2x500SEC Euro early 80s/ 560SEC 88" Euro / Object 500
Location: EUROPE
Posts: 44
Mentioned: 0 Post(s)
Quoted: 15 Post(s)
(Thread Starter)
OTHER GOOD TIPS or other sensor or problems to adress from experts here? , exept gogi sensor (thanks gogi)

Best
GT1 is offline  
post #28 of 92 (permalink) Old 06-24-2019, 01:45 PM
BenzWorld Elite
 
John350's Avatar
 
Date registered: Nov 2014
Vehicle: 1990 350SDL, "Grandpa's Roadster" Project Car
Location: New Hampshire
Posts: 2,897
Mentioned: 9 Post(s)
Quoted: 824 Post(s)
Wire the fan to run then repeat your overheat test. I think you'll find it still overheats. If not, it should actually be pretty easy to fix the electric fan. Unlikely all the sensors are bad, so I'd first look at the power side of the circuit.
John350 is offline  
post #29 of 92 (permalink) Old 06-24-2019, 02:40 PM
BenzWorld Elite
 
Date registered: Nov 2002
Vehicle: '82 500sec euro, '95 Ford F150
Location: West Palm Beach, Fl
Posts: 1,545
Mentioned: 3 Post(s)
Quoted: 150 Post(s)
Quote:
Originally Posted by gogi View Post
That leaves the pressure switch out of the equation no? If a blade fuse is used to jump the two wires going to P/Switch that also checks the circuit integrity from there.
Also do what you suggest and the whole circuit gets tested and there are no unknowns.
Geez. What I suggested is simply a way to test if the fan works, that takes a few seconds, as the OP was asking.
roadhouse is offline  
post #30 of 92 (permalink) Old 06-24-2019, 02:52 PM
BenzWorld Elite
 
Date registered: Nov 2002
Vehicle: '82 500sec euro, '95 Ford F150
Location: West Palm Beach, Fl
Posts: 1,545
Mentioned: 3 Post(s)
Quoted: 150 Post(s)
One mod I’ve done in the past on a car that was running hot, is I’ve replaced the 110*C sender with a temp gauge sender. I also tapped into the dryer pressure switch and hooked it to this sender.
What this does, is the fan comes on low speed at about 60-is Celsius, and stays running wether the AC is on or not.
One can of course just ground the wire on the 110*C sender, but that would make the fan go full speed as soon as the ignition is on. It’s noisy, and consumes a lot of power.
roadhouse is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W126 S,SE,SEC,SEL,SD,SDL 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



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