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

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1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

i did this and it helped...

https://www.youtube.com/watch?v=Jo0HZ7KbNSA

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Ya that would work but I’m trying to take the Work load away from the Aux fans. The main fan should do most of the work. If there ever was a problem with the electric fans the car would surely cook

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1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

Iirc the electrics are there for the a/c system more so than the engine cooling. As long as engine stays at 110 and ac blows cold I'd run it.

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Jim

does the main cooling fan roar at all?

in february, I helped a person here with a W124 E320 and got him a good fan clutch and installed it. That thing definitely roars now when driving in 99F weather and the AC cranked up, the engine temperature is pretty stable at the usual 100C mark.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Your best bet is to buy a brand new BEHR fan clutch. Been there done that.

You can also put in an electric fan with an adjustable probe switch that slots into your radiator. Of course switch the fan with a relay.

The reason why a radiator probe is better than a cylinder head sensor is because your engine/transmission will run cooler (with a cylinder head switch your cut in temp has to be higher that the thermostat temp. otherwise the fan will run all the time)

Running your car at 110 will damage your head gasket (already a weak point on M104), wear out your transmission sooner, wear out your rubber/plastic parts on the engine and cause leaks.

It pulls air but I can’t say it roars. It’s a bran new behr. All 3 cars have the same Setup.

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1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

The electric fan(s) should be on pretty much any time the A/C is running. Ambient temps over 85 degrees should absolutely have the fan on if the A/C charge is correct and the compressor is running. This will be low speed, not high speed and is designed to help the A/C work better, not to cool the radiator.

The fan clutch is thermostatic. If air is not reaching the thermostatic element, it will not engage. Make sure that the radiator and A/C condenser are clean, they can plug up with debris and block the airflow to the thermostatic element. If the engine is running hot and the cooling system is working as it should be, that fan should be engaged and moving a large amount of air. If you open the hood and rev the engine, you should hear it whining and see/feel a substantial increase in airflow from the fan.

New doesn't always mean good. Behr clutches can be hit or miss. Verify that it's working properly before dismissing it as a possibility.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Just installed a new Nissens radiator, Behr fan clutch, thermostat and did a flush. Temperature stays rock solid just a pinch above 80. M103 1990 300SE.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

Everything on the cars is fresh. I been replacing the fan clutches On all 3 cars every other year or so. A lot of money going down the drain. I feel the main fan should be doing more work than what it is currently putting down. I’m going to swap in an electric fan on my w124 and see how much better it works. It’s hot where I live. 100-115 degrees Typically the whole summer till Late September. It’s calming to have a car that is functioning within a normal area instead of 2 **** hairs from boiling over

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1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero

Don't know if this helps, but our fan clutches for Mercedes lean toward the "aggressive" side of the spectrum (we've received some complaints that they make the fan blade too loud). But if you're looking for maximum cooling, an aggressive clutch might help.

Our engineers are currently looking into tuning them less aggressively in the future, but we haven't made any running changes on the production line just yet.

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snj:

Prior to settling on air flow as the culprit, ensure that the thermostat is operating correctly. If it is not fully opening, it is also not fully closing the by-pass circuit. If the by-pass circuit remains partially open, the recirculated hot water will defeat radiator and air flow capacity.

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.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

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

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John Roncallo

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!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer