w124 Aux fans - Page 2 - PeachParts Mercedes-Benz Forum

87tdwagen · #16 05-11-2021, 02:27 PM

Quote:

Originally Posted by Diseasel300

Additionally, high speed is not triggered by the refrigerant circuit. Earlier cars have a temperature switch somewhere in the cooling system (location varies with engine) that triggers the high speed relay. Later cars have a temperature sensor in the cooling system that feeds the climate control unit to accomplish the same task. High speed fan is always a function of coolant temperature, not refrigerant temperature/pressure. This isn't a great way to trigger high speed fan operation since your engine is running hot and you have a 5-10˚ window before the compressor is disabled due to high temp.

Absolutely correct, I stand corrected, the high speed is governed by a temp switch in the cooling system, that you can have some flexibilty to adjust based on installing different colored temp sensors to trigger the fan on at different temperatures. On the OM603, I believe there are 3-4 temp switches available.

In my case, being in South Florida, we rarely get days below 85 ambient so my low is always on

speednjay · #17 05-11-2021, 02:40 PM

The only fan clutch that actually worked at slow speeds was the uro. Everything else: mb, hella, behr.. about a dozen more were too soft. On my diesel the clutch seized and destroyed the radiator. After that a drama nice electric was put in.

Usaguy · #18 05-11-2021, 02:43 PM

Quote:

Originally Posted by tjts1

I'm sorry but that's simply not true. In a hot climate and low speed the AUX fans do all the work while the viscous clutch fan is a glorified paper weight. Until I learned about the cool harness mod and later complete electric cooling conversion I would sit there and watch the temp gauge creep upward of 100c until the aux fan kicked in. The clutch would lock up and pass the rolled up news paper test, the problem is the fan is too dinky to do any good at idle when the air temp is 100f+.

The clutch fan is a garbage solution for the om603/m103/m104. There's not enough room between the engine and radiator to fit a vicous clutch fan large enough to do the job. The less powerful om602 was fitters with a much larger fan (wider blades) than the om603.

The Fan clutch does ALL of the engine cooling.

Aux fan is just for a/c and emergency. Euro market w124 without a/c don't even have them.

I once drove my m103 powered car in 90 degree traffic and the temp was dead steady at 87 without aux fans.

That said I have a BEHR fan clutch because most others I tried were junk or quickly became junk.

ah-kay · #19 05-11-2021, 03:19 PM

Quote:

Originally Posted by 87tdwagen

Absolutely correct, I stand corrected, the high speed is governed by a temp switch in the cooling system, that you can have some flexibilty to adjust based on installing different colored temp sensors to trigger the fan on at different temperatures. On the OM603, I believe there are 3-4 temp switches available.

In my case, being in South Florida, we rarely get days below 85 ambient so my low is always on

Red: 006-545-42-24 (100/110)
Green: 006-545-45-24 (105/115)
Grey: 006-545-61-24 (105/120)
Blue: 006-545-64-24 (105/128)

These are the 4 sensors ( 3 prongs ) you can use in the OM603 engine. The first temperature number turns on the aux fan at HIGH speed, the second temperature kills the a/c just in case the coolant temp gets too high. The high pressure sensor at the receiver drier turns on the aux fax at SLOW speed at about 290psi. That is all to it for the function of the aux fan.

The fan clutch should be able to cool the engine under normal working conditions. The aux fan is a just in case condition otherwise Mbz would not design it in. I had at one time hard wired the aux fan to run continuously to get me home as the engine was overheating big time at Death Valley.

I am only interested in facts, not arguments.

tjts1 · #20 05-11-2021, 08:44 PM

Quote:

Originally Posted by christuna

The Fan clutch does ALL of the engine cooling.

Aux fan is just for a/c and emergency. Euro market w124 without a/c don't even have them.

I once drove my m103 powered car in 90 degree traffic and the temp was dead steady at 87 without aux fans.

That said I have a BEHR fan clutch because most others I tried were junk or quickly became junk.

Well it's doing a shlt job of it.

Quote:

Originally Posted by speednjay

The only fan clutch that actually worked at slow speeds was the uro. Everything else: mb, hella, behr.. about a dozen more were too soft. On my diesel the clutch seized and destroyed the radiator. After that a drama nice electric was put in.

Now that's something I haven't tried.

ke6dcj · #21 10-06-2021, 03:33 PM

Quote:

Originally Posted by ah-kay

Red: 006-545-42-24 (100/110)
Green: 006-545-45-24 (105/115)
Grey: 006-545-61-24 (105/120)
Blue: 006-545-64-24 (105/128)

These are the 4 sensors ( 3 prongs ) you can use in the OM603 engine. The first temperature number turns on the aux fan at HIGH speed, the second temperature kills the a/c just in case the coolant temp gets too high. The high pressure sensor at the receiver drier turns on the aux fax at SLOW speed at about 290psi. That is all to it for the function of the aux fan.

Will any of these work on a gasser M104 or M119 ?

:-) neil

ah-kay · #22 10-06-2021, 05:46 PM

Quote:

Originally Posted by ke6dcj

Will any of these work on a gasser M104 or M119 ?

:-) neil

You only need one for the car. The color code is for the temperature. It should work with gas cars.

back-seat-driver · #23 10-07-2021, 03:00 AM

There are no absolutes with W124's cooling systems. I've had four and they've all behaved differently.
There are many ways to skin the cat. And many people who've spent loads of money fixing it and replacing it's components, only get a marginal improvement.
The viscous fan has been marginal on all my W124s but one. The aux fans did most of the cooling for when it was really hot on the other 3.

I say this as someone who lived in the San Fernando valley in Los Angeles (hot,) and drove to Phoenix (very bloody hot!) once a month or more. And drove all over So Cal plenty of times to go play rugby games (Las Vegas, San Luis Obispo, San Diego, and many places in between.)

Going up the Chiriaco Summit or Grapevine in summer; aux fans on even with no AC. Except for the one car which had a bonkers efficient cooling system and AC. (I bought that one in Phoenix, so it figures.) I haul arse on the highways so i'd be putting a lot of heat through the cooling system when it was already 110*F or more outside.

The one thing I keep repeating to all and sundry that will listen is that water has better heat dissipation than the coolant additives in your Zerex. Just make water a larger (60- 75%) component in your cooling system if you live in a really hot climate.
Flush the system frequently.
Replace the radiator every few years.