W124 coolant fan options - Page 2 - PeachParts Mercedes-Benz Forum

duxthe1 · #1 07-06-2020, 11:00 PM

I completely ditched the fan clutch and aux fans out front in my CE. I modified a 600W 203ch fan for a 124 shroud and built a controller for it. This allowed using a later style refrigerant temperature sensor instead of a pressure switch. I found out a couple of things along the way.

When dialing in the code for my fan module I found that I could run the fan full speed and still overheat sitting in traffic. Airflow was not the limiting factor. I found that if I held the accelerator to give a 750-800 RPM idle speed I could watch the temp gauge fall back to thermostat set point. At the ~600 RPM hot idle speed, there was insufficient coolant being circulated to handle a high heat load. I've been tuning the CIS module in my coupe and have electronically raised the idle speed. With these mods I never overheat. Absolute worst case scenario I see 93C, and am probably one of the coolest running 124s around. It took extraordinary measures to achieve this.

Without going down the rabbit hole to join me, there are a few things that can help. Gotta have a good fan clutch. Also need good airflow through the radiator. These cars are old enough that its a sure bet there is plenty of trash in bottom of the aux fan shroud blocking a fair percentage of it. Accumulation of dirt and crud in the condenser and radiator fins is costing heat transfer too. These cars need a full a/c charge.
I've seen cars that would cool but didn't have enough pressure to trigger the fans, resulting in overheating. Check the rotation direction of the aux fans. For the longest time replacement fans have had the wiring reversed in the connector. Many half assed techs have missed that detail. Lastly learn to accept that the system was marginal to begin with, and age doesn't make them better.

tjts1 · #2 07-08-2020, 02:39 AM

Quote:

Originally Posted by duxthe1

I completely ditched the fan clutch and aux fans out front in my CE. I modified a 600W 203ch fan for a 124 shroud and built a controller for it. This allowed using a later style refrigerant temperature sensor instead of a pressure switch. I found out a couple of things along the way.

When dialing in the code for my fan module I found that I could run the fan full speed and still overheat sitting in traffic. Airflow was not the limiting factor. I found that if I held the accelerator to give a 750-800 RPM idle speed I could watch the temp gauge fall back to thermostat set point. At the ~600 RPM hot idle speed, there was insufficient coolant being circulated to handle a high heat load. I've been tuning the CIS module in my coupe and have electronically raised the idle speed. With these mods I never overheat. Absolute worst case scenario I see 93C, and am probably one of the coolest running 124s around. It took extraordinary measures to achieve this.

What he said. On the OM603 you can get a smaller water pump pulley to spin the pump faster at idle. A similar pulley is available for the m103/m104. Between the small water pump pulley and electric puller fans behind the radiator, it completely fixed my overhearing issue especially at idle. A mechanical fan can only spin as fast as the engine. An electric puller fan can run max speed at idle. It never exceeds 90c now.

Prius electric fans retrofitted to the pull air through the w124 radiator. It ain't pretty but it works.

Roncallo · #3 07-07-2020, 09:19 PM

Quote:

Originally Posted by speednjay

I have a w124 my wife has a w124 and my step daughter has a w124. So basically I have 3 cars to keep up with. we all live in the hottest part of the state. There has got to be a better way to keep these cars cool. New radiators, Mercedes fan clutch, but most of the cooling seems to be from the electric fans which doesn’t make sense. Basically the fans intended to be used as an auxiliary are now ruining 90 percent of the time. It doesn’t overheat but the electric fans are running full blast to keep the temps under 110

One idea I had was to just ditch the clutch fan and put a nice big electric in there with a variable ramp up speed. Clearly the clutch fan isn’t doing the job

Is the clutch fan working.

If you intend to go electric I'm considering these guys. These are the lowest profile fans I know of. Give them a call if you cant find what you want. They have much more than they put on there websight.

Product Category: Fans & Shrouds Archive | Cooling Components

Sugar Bear · #4 07-07-2020, 11:06 PM

What is the coolant to water ratio? Excessive coolant reduces heat transfer, in a warm climate you can run less coolant. Consider trying an emulsifier such as Red Line Water Wetter.

Good luck!!!

lsmalley · #5 07-12-2020, 02:24 AM

Quote:

Originally Posted by speednjay

I have a w124 my wife has a w124 and my step daughter has a w124. So basically I have 3 cars to keep up with. we all live in the hottest part of the state. There has got to be a better way to keep these cars cool. New radiators, Mercedes fan clutch, but most of the cooling seems to be from the electric fans which doesn’t make sense. Basically the fans intended to be used as an auxiliary are now ruining 90 percent of the time. It doesn’t overheat but the electric fans are running full blast to keep the temps under 110

One idea I had was to just ditch the clutch fan and put a nice big electric in there with a variable ramp up speed. Clearly the clutch fan isn’t doing the job

Go with the 600 watt newer C/E/S class fan. I did this set up about 2 years ago and my car will sit at about 90*C, with the a/c on, not moving, with an ambient outside temp of about 117*F. You can ditch the 2 aux fans in the front also as they just impede air flow. Here is a link of the car idling with the a/c on in about 120*F weather: https://photos.google.com/share/AF1QipOGtBKmZsfng_qahECam5Ob8hq11c3QS-Fmx0O_00L0QurjMsMHxNGRCL_FjLfnKQ/photo/AF1QipNwhqn_TJuox57Zfcbe2gGQ1bu8iITOAEzIw1qe?key=RXZYZUNlTUlJd1o0dmFSV0YyM3JoRWJVOFFLOW53

Also here is the thread I created a while back while on the hunt for the perfect cooling system for the m103: http://www.peachparts.com/shopforum/tech-help/394107-newer-mb-600-watt-electrical-fan-m103.html

turbobenz · #6 07-20-2020, 10:42 PM

Theres a reason MB ditched the clutch fan and went all electric. Theres a few probs. I had the issue of overheat with AC on. Litereally every thing new, OEM parts. All behr stuff. Figured out that with AC on my fan clutch was clutching agressively at idle which causes condenser to cool enough to never kick the high side switch on. So AC is happy while your engine is cooking basically. Probably my brand new OEM switch is just junk and not kicking on at the right temp. So I wired a relay to turn on the low speed aux fan circuit whenever the clutch is engaged. This helped a lot to keep the system from running away, especially after getting off freeway. Interestingly enough if your system has low refrigerant this switch will not kick on and your car will run hotter as well, so make sure you got a proper charge if you use the AC. I also removed the plastic cover from the front of the condenser and cut bottom half off. This blocks a massive amount of airflow from the bumper when the vehicle is in motion, I noticed lower freeway temps after this.

All this helped but I'm kind of crazy so I fabbed up a bracket to mount an all brass ford heater core in the wheel well with a spal 5.5 inch fan on it. Now literally nothing will make it go above 100 with AC on. Still wish it would just sit at 80C like a newer mercedes but I guess that's the power of a 900 watt fan and feedback loop speed controller. I thought about it but theres very little room on my 300CE for a fan behind the radiator and I'd need to upgrade the alternator as well.

I think if I could just get a smaller diameter fan pulley Id be able to move more heat than all the mods Ive done so far but I can't seem to find anything even close that would work. That's the real ticket IMO, just move more air at idle from the clutch fan. ACM clutches are also "aggressive".