E46 M3 Cooling Issue: Replace Fan Clutch or Upgrade to Electric Fan?

[M3Mino]

Hey everyone, I’m looking for some advice on my E46 M3 cooling setup.

The other day my coolant temps got higher than I’ve ever seen before. It was extremely hot outside (117°F here in Vegas), and I know the conditions were pretty extreme, but it still caught my attention. I checked my fluids and everything looks normal, and the car is running well otherwise.

After doing some digging, I noticed my fan clutch bolt looks pretty rusty, so I’m wondering if the fan clutch could be getting weak or starting to fail.

My question is: should I just replace the fan clutch and keep the OEM setup, or would it be worth switching over to an electric fan setup?

The car is a 2006 E46 M3 running a VF570 supercharger with supporting mods, including a CSF triple-pass radiator and upgraded cooling components. I enjoy driving the car a lot, especially during the summer here, so I want to make sure the cooling system is as reliable as possible.

For those who have made the switch to an electric fan (Mishimoto or other setups), was it actually worth it? Any downsides compared to fixing the factory fan clutch?

Thanks for the advice!

[samthejam]

Under what conditions is your car running hot?

CSF radiators are very hit or miss for their product in the E46 M3 in the community. Mostly leaning towards very negative. Triple passes are also not very good for lower air speeds, and also specifically the CSF they are reported to be inferior than a stock rad by most on track. Plenty of threads to research this product further.

Onto the fan clutch.

This is not the best check for a clutch fan but it will tell you if it's get up and go and has got up and left. When it at operating temp or running warm, get a roll of paper towels or something similar. Try and stop the fan, if you can stop the fan the clutch fan it is not engaging.

I would get a Koyo or OE radiator and troubleshoot your fan clutch. I personally like clutch fans but with parts quality now can be difficult to get something not bad out of the box. Efan has some other benefits like can change its engagement with the DME tune but that is pretty advanced installation.

[M3Mino]

Under what conditions is your car running hot?

CSF radiators are very hit or miss for their product in the E46 M3 in the community. Mostly leaning towards very negative. Triple passes are also not very good for lower air speeds, and also specifically the CSF they are reported to be inferior than a stock rad by most on track. Plenty of threads to research this product further.

Onto the fan clutch.

This is not the best check for a clutch fan but it will tell you if it's get up and go and has got up and left. When it at operating temp or running warm, get a roll of paper towels or something similar. Try and stop the fan, if you can stop the fan the clutch fan it is not engaging.

I would get a Koyo or OE radiator and troubleshoot your fan clutch. I personally like clutch fans but with parts quality now can be difficult to get something not bad out of the box. Efan has some other benefits like can change its engagement with the DME tune but that is pretty advanced installation.

For some additional context, I recently moved to Las Vegas. The car never gave me any cooling issues when I lived in California. Last week it was around 117°F outside, and that's when I noticed the engine temp climb to about the 3/4 mark on the gauge. It honestly caught me off guard because I'd never seen it do that before.

The interesting part is that as soon as I got on the freeway and airflow increased, the temp dropped right back to the middle and stayed there. That's why I'm wondering if this points more toward the fan clutch not doing its job at low speeds rather than the radiator itself.

I appreciate the information about the CSF triple-pass radiator. I think my experience may be a good example of what people have been saying about them. I wasn't aware they had such a mixed reputation on the E46 M3, so I'll definitely do some more reading.

I'm going to inspect and test the fan clutch first before replacing any major components. I also watched a few videos on the electric fan conversion. I don't think the electrical side is something I'd be comfortable doing myself, so if I decide to go that route, I'll probably have a shop install it. While it's apart, I'm also thinking about having them flush the cooling system and replace all of the coolant hoses with new silicone ones.

For the electric fans any brand suggestions? I keep reading bad things about Mishimoto even thought I think they are the only ones that actually make a kit for our cars.

[DrM3]

Hello fellow vegas e46m friend,

I just went through a similar issue with my car. Temps were climbing and dropping only with the A/C ON. Our heat has been wild this summer.
I have read quite a few threads and many owners have discussed the temps moving up and returning back to normal; some are saying it is nothing to be concerned about.
Since I did not have full history on the cooling system, went ahead and did the fan clutch, coolant flush, radiator and thermostat. Temps have held well, slightly going up but nothing as high as they were before. The radiator was showing signs of blockage and flow issues. Water pump was tested and showed no signs of problems.
If you are up for a cruise, let me know, look forward to meeting you!

[sapote]

208F=97.778 °C, it’s normal for the hot weather.

[Obioban]

Like the radiator "upgrade", electric fan "upgrades" generally flow less than the stock mechanical.

[Rudbari]

Get the oem radiators and then check your clutch fan and if need replace .
i would say with clutch fan

I own ess 575 kit my self and I am with clutch fan and oem radiator

[ac427]

Hello fellow vegas e46m friend,

I just went through a similar issue with my car. Temps were climbing and dropping only with the A/C ON. Our heat has been wild this summer.
I have read quite a few threads and many owners have discussed the temps moving up and returning back to normal; some are saying it is nothing to be concerned about.
Since I did not have full history on the cooling system, went ahead and did the fan clutch, coolant flush, radiator and thermostat. Temps have held well, slightly going up but nothing as high as they were before. The radiator was showing signs of blockage and flow issues. Water pump was tested and showed no signs of problems.
If you are up for a cruise, let me know, look forward to meeting you!

How did you go about testing the water pump?

[liam821]

Like the radiator "upgrade", electric fan "upgrades"generally flow less than the stock mechanical.

The stock mechanical fan is outstanding; you need a fairly large (high amperage) brushless electric one to come close.

[sapote]

For those who have made the switch to an electric fan (Mishimoto or other setups), was it actually worth it? Any downsides compared to fixing the factory fan clutch?

stock setup has the front efan and clutch fan, with clutch fan running all the time. switch from clutch fan to efan then only one fan to do the work and it will worn out/burned out sooner.
I don't see the gain of switching out the clutch fan.

[Kevin2772]

Like others have mentioned, i had the same problem driving in high heat with AC ON. When i would turn it off and be moving, it would bring it back within range. Mine was the fan clutch. Got a replacement installed OEM and have not had a cooling problem since.

[ac427]

Like others have mentioned, i had the same problem driving in high heat with AC ON. When i would turn it off and be moving, it would bring it back within range. Mine was the fan clutch. Got a replacement installed OEM and have not had a cooling problem since.

Which make of fan clutch did you have and which make did you replace it with?

I am curious because the Sachs fan clutches are hard to come by.

[0-60motorsports]

i got a sachs tropical version a few months ago LOL 2100010032

[ac427]

i got a sachs tropical version a few months ago LOL 2100010032

Bloody hell, tropical 😄

Thanks for the part number mate 👍