W124 e-fan amp draw - PeachParts Mercedes-Benz Forum

speednjay · #1 11-11-2020, 04:07 PM

For a fan clutch to electric fan swap, what kinda fan motor amps should I look for? Was thinking something around 10 amps.

Zulfiqar · #2 11-12-2020, 11:55 AM

Quote:

Originally Posted by speednjay

For a fan clutch to electric fan swap, what kinda fan motor amps should I look for? Was thinking something around 10 amps.

The twin fan setup on the W124 condenser sucks about 24 amps.

Are you installing a PWM type setup with a probe in the radiator fins? Like a SPAL fan?

speednjay · #3 11-12-2020, 03:47 PM

Quote:

Originally Posted by Zulfiqar

The twin fan setup on the W124 condenser sucks about 24 amps.

Are you installing a PWM type setup with a probe in the radiator fins? Like a SPAL fan?

Ya the fan clutch setup is junk. Tired of replacing Expensive fan clutches that don’t even work. Car temp spikes 110 till the aux fans kick on and cool things down. It’s like I don’t even have a main fan. I have 3 good running w124s and they all do the same ****.

Sugar Bear · #4 11-12-2020, 08:27 PM

Agree about the fan clutches...

Climate permitting, it also helps to run less than 50/50 coolant and RedLine Water Wetter.

Also added a resistor in the fan sender circuit to make the aux fan turn on earlier.

Good luck!!!

rayhennig · #5 11-13-2020, 03:01 AM

I can't help feeling that replacing the fan clutch, as described here, may be an attempt to fix problems elsewhere. The standard configuration with a 2 year old Sachs fan clutch worked well for me throughout summer with temperatures up to 40C. This with an M104 engine and 5-speed auto.

The highest engine temperature I saw after hill climbs with aircon working was 93C. Up around 5C from normal. Nothing to worry about.

If you're regularly seeing 105C when the fans kick in, it may not be a problem. That's what they are supposed to do. Maybe your weather is hotter and your hills longer!!

As said, I feel that maybe you're trying to cure the symptom rather than the cause.

Also, it's worth measuring the ACTUAL engine temperature. Gauges are not very accurate.

Good luck, anyway.

RayH

speednjay · #6 11-13-2020, 10:04 AM

I believe everything is functioning as normal except the main fan. It is useless. The aux fans are doing almost 100 percent of the cooling work.

rayhennig · #7 11-13-2020, 10:07 AM

Quote:

Originally Posted by speednjay

I believe everything is functioning as normal except the main fan. It is useless. The aux fans are doing almost 100 percent of the cooling work.

Ah. Maybe it's broken and you need a new one. That happened to me and the replacement's doing its job. In my case, it was the inverse in that the clutch was permanently locked and things were a bit noisey.

R

Diseasel300 · #8 11-13-2020, 10:23 AM

Clutch fans rely on the air hitting their bimetal element to be hot enough to enable the clutching mechanism. If the radiator or A/C condenser are plugged with junk in the air path leading to the clutch bimetal, it will engage much later or not at all. Repeated failures suggest either cheap off-brand parts or a blocked airflow path. If the clutch isn't Sachs, ACM, or OE Mercedes, you bought the wrong one.

Zulfiqar · #9 11-13-2020, 11:18 AM

Quote:

Originally Posted by Diseasel300

Clutch fans rely on the air hitting their bimetal element to be hot enough to enable the clutching mechanism. If the radiator or A/C condenser are plugged with junk in the air path leading to the clutch bimetal, it will engage much later or not at all. Repeated failures suggest either cheap off-brand parts or a blocked airflow path. If the clutch isn't Sachs, ACM, or OE Mercedes, you bought the wrong one.

Very true

a blocked radiator and condenser can cause the fan clutch to never work. The fan clutch needs to be recieving very hot air right from the front of it - meaning if some channels are blocked in the radiator and they are right infront of the clutch, it wont kick on.

My old W124 had a BEHR fan clutch originally, I refilled it with some 7000 wt silicone oil (trial and error) and it eventually started working good but more as an on/off fan like a heavy truck (quiet as a mouse or loud as a tornado) - I then changed it to a Horton/Sachs clutch from a 98 E300 with a higher blade count fanwheel and it worked beautiful after that - gentle and smooth engaging, low noise type.

In both cases the engine temperature never exceeded 100C on the dash which I also cross checked with an IR gun on the cyl head itself.

oldsinner111 · #10 11-13-2020, 01:24 PM

when I first mounted mine on my 617, I used a jeg's thermo switch, I tape temp probe to thermstat hose coming out of head. I always use a lower t sat. I did not use a relay which burnt fuse up. Finally used one rated for 50 amps. to be sure.My fan only turned on in stop and go traffic in town.

speednjay · #11 11-13-2020, 03:23 PM

I’ve used all the fan clutch brands. The only one that worked was the uro because it was pretty much mildly tight. Moved a lot of air while sitting in traffic. Aux fans rarely came on for temps. My daughter And wife also drive a w124 And it doesn’t leave them, or me, confident when the water gauge is oscillating 2 **** hairs from meltdown. Im don’t with it.

Going to get a variable speed fan setup that ramps up the speed as needed. 16” fan somewhere around 10Ish amps and around 1800+ cfm. I believe this setup would suffice Without putting too much burden on the electric system. I did this my w210 diesel and is was a beautiful thing

URO Parts Support · #12 11-16-2020, 11:57 AM

^ Indeed, historically many of our Benz fan clutches have been on the aggressive side of tuning and engage sooner (at a lower temp) than OEM. Our engineers have been working with the production line to get them more in line with OEM, but we don't have the production units "relaxed" just yet.