Mercedes-Benz Forum - Reply to Topic
Topic: 500SEC Boiling when at idling (stand-by) app 600rpm for more than 6-8min Reply to Thread
Title:
Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:
 

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










  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
07-26-2019 01:56 PM
Heikkif If lower hose from radiator to engine is hot coolant is circulating well but is not getting cooled in the radiator by air flow trough the radiator.
07-26-2019 01:46 PM
GT1
Quote:
Originally Posted by Heikkif View Post
Checked today how warm the lower hose from radiator is after car has been driven warm and is idling for a couple of minutes on my 420 SEC. It is very close to ambient temperature. This is with the belt driven fan only as this car no AC. One can reach that hose by kneeling at the front of the car.
Think mine(same one) is quite hot at same test.

So as i understand, poor circulation on my cooler. Thank you for reply.
07-26-2019 01:44 PM
GT1
Quote:
Originally Posted by John350 View Post
This will probably be my last post on this thread.

As I've stated several times before, his fan does not work this way. His fan comes on only in response to refrigerant temperature. It has only one speed. If the AC is on and the temperature of the refrigerant, as measured by the temperature sensor on the receiver/dryer, exceeds 52*C the aux fan relay coil is grounded through the temperature sensor switch and the relay turns the fan on. Refer back to post 43 for the schematic.
Well recieved. trust you. Understood.

Will test it, ohm it, and take from my other car and re-test with that one.

Thanks again.
07-26-2019 01:13 PM
Heikkif Checked today how warm the lower hose from radiator is after car has been driven warm and is idling for a couple of minutes on my 420 SEC. It is very close to ambient temperature. This is with the belt driven fan only as this car no AC. One can reach that hose by kneeling at the front of the car.
07-26-2019 01:04 PM
John350
Quote:
Originally Posted by rumb View Post
There should be 2 sensors. One is a 2 pin on your head or near thermostat, not sure on your engine. if you jump the 2 pins/wires the fan should turn on high....The second is the pressure switch on the bottom of the dryer. IF your ac has enough pressure it should turn on shortly after your turn fan on AC at low speed.
This will probably be my last post on this thread.

As I've stated several times before, his fan does not work this way. His fan comes on only in response to refrigerant temperature. It has only one speed. If the AC is on and the temperature of the refrigerant, as measured by the temperature sensor on the receiver/dryer, exceeds 52*C the aux fan relay coil is grounded through the temperature sensor switch and the relay turns the fan on. Refer back to post 43 for the schematic.
07-26-2019 11:38 AM
GT1
Quote:
Originally Posted by rumb View Post
4. The fan clutch i can change as well. Any link to a cheap one for my type ?

Find a good Behr one. Not a part to buy cheapest.
Ok, any tips?
thank you
07-26-2019 11:11 AM
rumb 4. The fan clutch i can change as well. Any link to a cheap one for my type ?

Find a good Behr one. Not a part to buy cheapest.
07-26-2019 11:03 AM
GT1
Quote:
Originally Posted by rumb View Post
There should be 2 sensors. One is a 2 pin on your head or near thermostat, not sure on your engine. if you jump the 2 pins/wires the fan should turn on high. You can test for ohms, starts around 6 when cold and goes up to @>1000 when hot. This one is easy to replace, you may lose just a small amount of coolant when you replace - dont forget a new sealing ring.

The second is the pressure switch on the bottom of the dryer. IF your ac has enough pressure it should turn on shortly after your turn fan on AC at low speed. If your R12 is low it wont turn on. You can again jump these 2 wires and the fan should turn on low. This one is harder to replace as you must evacuate the AC system.

Please jump the 2 sensors mentioned and report back what happens with the electric fans.
Super, i understand. Will do tomorrow. Thank you much. Best
07-26-2019 11:02 AM
rumb
Quote:
Originally Posted by GT1 View Post
PROBLEM 1.

FOR ELECTRICA FAN. AC WORKS FINE. FAN NOT BROKEN. WHICH SENSOR TRIGGERS THE FAN. AS I UNDERSTAND IN MY EURO 1984 THERE IS ONLY AT AC ON. SO WHICH SENSOR TO FOCUS ON. AUX FAN NEVER START. NEVER. BUT AC WORKS FINE. STILL I WANT TO SORT IT OUT AND HAVE IT RUNNING AS IT SCHOULD.

ONLY DWG OG PICTURES PLEASE. REGARDS AUX FAN START WHEN AC ON.

Thanks for answer on above, only.
There should be 2 sensors. One is a 2 pin on your head or near thermostat, not sure on your engine. if you jump the 2 pins/wires the fan should turn on high. You can test for ohms, starts around 6 when cold and goes up to @>1000 when hot. This one is easy to replace, you may lose just a small amount of coolant when you replace - dont forget a new sealing ring.

The second is the pressure switch on the bottom of the dryer. IF your ac has enough pressure it should turn on shortly after your turn fan on AC at low speed. If your R12 is low it wont turn on. You can again jump these 2 wires and the fan should turn on low. This one is harder to replace as you must evacuate the AC system.

Please jump the 2 sensors mentioned and report back what happens with the electric fans.
07-26-2019 10:54 AM
GT1
Quote:
Originally Posted by John350 View Post
This is a good sign, but not proof, that the fan clutch is OK.


Increasing the RPM increases the fan speed. This points toward the fan clutch as the problem.


The fan is always driven by the viscus fluid in the clutch, sort of like a torque converter, or an old style "fluid coupling". It is sort of coasting along. When the air coming off the radiator reaches a certain temperature there is a thermostatic device that closes a passage in the clutch and forces the fluid to drive the fan more efficiently, and so at a speed closer to the actual speed of the engine. The increase in speed causes an increase in fan noise. The fact that you do not hear it leads me to believe the fan clutch is not working correctly.



What you want to do is try to flush the air passages through the radiator and condenser that the air needs to follow. Spray water through the radiator in the opposite direction that the fan pulls the air. You will likely have to loosen and move the fan shroud to do this.

If you get a lot of stuff coming out, or cannot get the water to flow freely, you should separate the condenser from the radiator so you can flush them each separately. Together they form a maze that tends to trap stuff between the two.

The fact that the engine cools when you increase the engine speed points more toward the fan clutch than anything else. If blockage were the issue, driving faster or raising engine speed would not help.

PROBLEM 2 (AND MOST IMPORTANT, OVERHEATING):

1. For those think i been fooling around for weeks. No. I have 3other cars we renovating as well at the same time, other brands, as this one been working on 3times the last month. As well as Travel 60% of the year. Thanks.

2. John you are abosolutely correct, there is a language barrier, i try my best, but dont catch all tech.english as good as you guys. Sorry for misunderstandings.

3. So i will try to flush as your advice. Any more comment ?

4. The fan clutch i can change as well. Any link to a cheap one for my type ?

You have contributed brilliant. Appriciated a lot. thank you.
This thread has more than 10 replies. Click here to review the whole thread.

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

 

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