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Discussion Starter #61
So see attached picture. I only want comment from people who knows. And i dont want comment like... why are you still etc. Thanks.

New test at reciever/Drier:

nr. 1 PS = cables energized with 12V as soon as i turn on ignition ( not need to start car) / ignition off = 0V
nr. 2 PS = 0V when ignition on(off) or motor running. But when Aircon switch is turned ON = 12V on the cables for this PS as well.

Correct ?
Any comment ?

Thank you for serious answer.
Best
 

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I would be curious how hot the lower coolant hose from radiator is? How hot/cool should it normally be? If it is too hot then it is a problem with air circulation or efficiency of the radiator. If it is cold enough then it is a problem with coolant circulation.
 

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STOP!!!

The electric fan has nothing to do with your overheating problem. It is only there to increase the efficiency of the AC system and you have stated that the AC works fine.

Once you figure out the overheating issue you can worry about the electric fan.

If you can't ignore the electric fan, wire it on and wait for the car to overheat again, proving it is not the problem, so we can get past it and move forward.

Your overheating problem is most likely either a bad fan clutch or a plugged or faulty radiator. I'm guessing your car will overheat regardless of whether the AC is running or not. Please confirm this.

When the engine is running hot you should hear the mechanical fan start making a roaring noise indicating the clutch is engaged. This is very noticeable at speeds above idle. If you do not hear it, suspect a problem with the fan clutch.

Look in the grill of the car. Look for debris blocking the airflow through the condenser and radiator. Sometimes it gets trapped between the condenser and the radiator and is hard to see. Try spraying water from a hose through the radiator from the engine side forward. Air needs to be able to flow through there or you will not get effective cooling.

Probe the fins of the radiator (not the condenser) with your finger. If they crumble or separate from the tubes of the radiator, you need a new radiator.

Use an infrared temperature sensor to measure the temperature of the radiator where the top hose comes in and where the bottom hose goes out. If there is not a big difference then the radiator is not shedding heat. Remove it and have it checked. Sometimes they can be cleaned out.
 

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Discussion Starter #64
STOP!!!

The electric fan has nothing to do with your overheating problem. It is only there to increase the efficiency of the AC system and you have stated that the AC works fine.

Once you figure out the overheating issue you can worry about the electric fan.

If you can't ignore the electric fan, wire it on and wait for the car to overheat again, proving it is not the problem, so we can get past it and move forward.

Your overheating problem is most likely either a bad fan clutch or a plugged or faulty radiator. I'm guessing your car will overheat regardless of whether the AC is running or not. Please confirm this.

When the engine is running hot you should hear the mechanical fan start making a roaring noise indicating the clutch is engaged. This is very noticeable at speeds above idle. If you do not hear it, suspect a problem with the fan clutch.

Look in the grill of the car. Look for debris blocking the airflow through the condenser and radiator. Sometimes it gets trapped between the condenser and the radiator and is hard to see. Try spraying water from a hose through the radiator from the engine side forward. Air needs to be able to flow through there or you will not get effective cooling.

Probe the fins of the radiator (not the condenser) with your finger. If they crumble or separate from the tubes of the radiator, you need a new radiator.

Use an infrared temperature sensor to measure the temperature of the radiator where the top hose comes in and where the bottom hose goes out. If there is not a big difference then the radiator is not shedding heat. Remove it and have it checked. Sometimes they can be cleaned out.
Thanks

1. Understood. i forget about aux fan for a while. AC is OK enough in my location this summer.

2. Regards fan clutch. If i try spin the machanical fan it spins maximum 20% of full round. quite hard to pull around. Comment ?

3. Overheat if AC is on or off (doesnt matter) at idling speed/stand still (in summer temp, more than 20+deg) . But if i rush the rpm though, temp drops and are ok.

4. Big mechanical fan runs all the time, please explain "mechanical fan start making a roaring noise indicating the clutch is engaged." And i have not noticed any particular roaring at temp 90-100-110 or other. only extra roar/sound if AC is turned on.

5. Probe the fins of the radiator (not the condenser) with your finger. I believe it feels ok...

6. Will try when i have time: "Try spraying water from a hose through the radiator from the engine side forward".

So to conclude, do i read you right if you think its either fan clutch or trapped debris ?


Sir can you point out where exactly where to flow water from engine side (where) to where (where you want me to open on in and out, pics or dwg please


very grateful thanks a lot, best
 

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While I agree somewhat with the statement that the electric fans are for A/C, There is obviously additional load on the engine when it is on, thus contributing to the increased engine temp. Sitting in hot traffic and you will need additional cooling help from the electric fans. When the asphalt temp is 130-140 degrees a lot of heat from that goes up to your engine.As all the system components age the temp becomes harder to control.

Since making sure the fans turn on as intended is easy enough I would verify all operation. If AC is on the fan should be on low. if the temp gets high enough the fan should turn on high. Your test of the sensors on you AC dryer seem to show what they should be doing. I would add the 1.1K ohm resistor on the 2 prong engine temp sensor that will make the fan turn on high @10 degrees earlier. with engine on if you jump those terminals the fan should turn on high. The is a temp/ ohm chart somewhere to test the device, but for @ $30 you can buy a new aftermarket one.

If your engine is getting very hot and the fans are not turning on, then something is wrong. If nothing else it is a safety net.

A cheap HF infrared temp gun you can measure the temps at top and bottom of radiator and all over the engine.
 

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2. Regards fan clutch. If i try spin the machanical fan it spins maximum 20% of full round. quite hard to pull around. Comment ?
This is a good sign, but not proof, that the fan clutch is OK.

3. Overheat if AC is on or off (doesnt matter) at idling speed/stand still (in summer temp, more than 20+deg) . But if i rush the rpm though, temp drops and are ok.
Increasing the RPM increases the fan speed. This points toward the fan clutch as the problem.

4. Big mechanical fan runs all the time, please explain "mechanical fan start making a roaring noise indicating the clutch is engaged."
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.

6. Will try when i have time: "Try spraying water from a hose through the radiator from the engine side forward".

Sir can you point out where exactly where to flow water from engine side (where) to where (where you want me to open on in and out, pics or dwg please
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.
 

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Thanks

1. Understood. i forget about aux fan for a while. AC is OK enough in my location this summer.

2. Regards fan clutch. If i try spin the machanical fan it spins maximum 20% of full round. quite hard to pull around. Comment ?

3. Overheat if AC is on or off (doesnt matter) at idling speed/stand still (in summer temp, more than 20+deg) . But if i rush the rpm though, temp drops and are ok.

4. Big mechanical fan runs all the time, please explain "mechanical fan start making a roaring noise indicating the clutch is engaged." And i have not noticed any particular roaring at temp 90-100-110 or other. only extra roar/sound if AC is turned on.

5. Probe the fins of the radiator (not the condenser) with your finger. I believe it feels ok...

6. Will try when i have time: "Try spraying water from a hose through the radiator from the engine side forward".

So to conclude, do i read you right if you think its either fan clutch or trapped debris ?


Sir can you point out where exactly where to flow water from engine side (where) to where (where you want me to open on in and out, pics or dwg please


very grateful thanks a lot, best
In addition to the good suggestions & advice given earlier, I'd like to amplify on an earlier point by member John350 when he said:

" When the engine is running hot you should hear the mechanical fan start making a roaring noise indicating the clutch is engaged. This is very noticeable at speeds above idle. If you do not hear it, suspect a problem with the fan clutch."

I would expect this warmed up engine fan 'roaring' sound to occur at engine speeds [especially] somewhere between 2500 & 3000+ RPMs and not below. When he says 'roaring', he's right.. It is unmistakably loud.

Good luck, you'll get it.

M.
 

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i had an episode today in my 500 SEL with the temp

this car always sits at 80 except in the summer when it creeps to 90/100

The radiator was swapped a few yrs ago...one thing i have noticed that it next does the Roar or the auxiliary fan never seems to go one either.

some may recall with MY SEC ive have / had higher temps issues, it would always run at 100, i changed radiator, clutch, stat and coolant and it runs at 90.


anyways back to the SEL, the sel AC has always been meh, the compressor probably leaks and when it is refilled it gets sorta cool but not cold

so in the summer when the temp is 85 plus outside, the car temps goes up to 100 but today it rose up a bit more with AC blasting on and or off... this morning when i drove it, with cool weather it was 80 c on the dot.. trying to figure where to go with this...
 

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Take the same steps you did with the Sec - new radiator , fan clutch and thermostat . These parts are all well worn on a 30 year old car even though they aren’t leaking and still doing a decent Cooling job
 

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yeah i figured steps will have to taken

crazy how the symptoms of each is quite different...

i dont know what else to do for the SEC because yeah it lowered the temp some but not to where i wanted it.....but i guess thats its
 

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If you don't have access to a Mercedes Benz parts catalog, autohausaz used the original MB parts #'s to use for reference (you'll need to type 1984, no SEC comes up with 83).
If your temperature sensor looks like the pic, connecting the 2 near poles with a screwdriver should bring on the electric fan (perhaps you have the single pole temp switch near thermostat?)
Around the electric fan, there should also be a resistor to be checked.

The edges of old and brittle coolant pressure containers can start leaking. I was surprised to see new Mercedes coolant overflow containers for only $36.99 @ autohausaz. Plus, a new pressure cap is not expensive, and provides peace of mind.

Attached 20-005.pdf cooling system
 

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You never answered Wilson. What you are pointing to is the refrigerant temp sensor.
I see the point. I only want a car to not boiling at 25C stand-still for only 5min ( WHICH IS NOT NORMAL) have 3 other same cars who dont at same temp.

So give me the solution if fan is not the problem. Whats the problem ?

Thanks
I gave up assuming that you have some type of cognitive or language impairment.

Do you not understand the logic?

You have been fooling around with the fan for weeks. All you have to do to eliminate it as a suspect or include it, it to hot wire the fan, let the car idle at temperature with the fan running and if it still over heats it is not the fan and you can relieve us all of the fan drama. If it never overheats, then the fan is indeed the suspect and you can start replacing parts.
 

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The guy is just stubborn and wants to be spoon fed info his way . He does not want to wire the auxfan to run to see if it stops his overheating
 

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Just to add to the confusion, I'd say that even if it does prevent the overheating, it's only masking the real problem, as he says it will overheat with the AC off, and the aux fan is part of the AC system.

I think there is definitely a language barrier, but I must admit his English is much better than my Norwegian.

If it were my car, I think I would pull the radiator out and have it checked, and clean the condenser fins at the same time. I would either replace the fan clutch at the same time, or do that next if the radiator does not correct the problem.
 

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If AC is on the fan should be on low. if the temp gets high enough the fan should turn on high.
One reason he's confused is he's getting false information thrown in. His fan does not operate this way. It comes on only in response to refrigerant temperature, only has one speed, and only runs when the AC is operating. If the car overheats with the AC off (he says it does) then the aux fan has nothing to do with his problem.
 

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One reason he's confused is he's getting false information thrown in. His fan does not operate this way. It comes on only in response to refrigerant temperature, only has one speed, and only runs when the AC is operating. If the car overheats with the AC off (he says it does) then the aux fan has nothing to do with his problem.

What you say is technically correct but making the fans turn on will definitely cool the engine down. If it's broken it should be fixed. If he does fix everything else and the electric fans still dont work correctly then engine will still overheat with the AC on, and the AC wont be working as efficient as it should.
 

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The aux fan has become a distraction from the root cause of his overheating. Given the amount of confusion displayed in this thread, I feel it is important to focus on what is critical, first. The engine overheats with the AC off. The aux fan is a red herring. (Not sure how that translates; it means a distraction.)
 

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the electric fan is not only for the AC . It is an auxiliary fan to cool the car when the mechanical fan is insufficient

Yes there may be other reasons his car is overheating , but getting the aux fan fixed should be step 1 since it’s an obvious problem
 

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the electric fan is not only for the AC . It is an auxiliary fan to cool the car when the mechanical fan is insufficient
The electric fan in his car runs only if the AC is on. His car overheats when the AC is off. Even if the fan were working, it would not be running with the AC off, ergo, it is not the cause of his overheating. It is a distraction. TMSAISTI!
 

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"
2) Waited 15min in 29C. To wait for temp to raise (stand by , maybe 500-600rpm, no trottle at all. Stand-still waiting.

the smaller fan in front never came on or started. Even when temp was between 110-120C. Then i stopped the test.

3) Tried to turn AC on and OFF during test. AC working OK. No prob.

Small (electric fan NEVER started all the way from cold engine 60C to hot engine 115C or something."

Seems his electric fans are NOT working. He should fix this first as it is the easiest to do.
 
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