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DYI: Mechanical Fan to Electric Fan Swap

245K views 467 replies 143 participants last post by  jasondotcom 
#1 ·
Let me just start off by saying I know this has been covered before, but no one has given a definitive answer, so I figured I'd make a thread for future reference.

I have an auto, and our cars come with a mechanical fan (engine driven) as well as an auxiliary fan to help with A/C and extra cooling power.

However, when I installed my supercharger, I had to remove the Aux fan to fit the intercooler. Because of that, the car would overheat when sitting at idle for too long, or if I ran the A/C (which wasn't even cold). I had to find a solution. I started looking at aftermarket fans, while also researching if I could swap an electric fan from a manual transmission E46.

I found a couple threads, but no real answers. I finally decided to PM the almighty and infinitely knowledgeable Mr. Nick G @ Technique Tuning, who informed me that it is a direct swap, and he performs this swap on his steptronic cars with no problems.

The mechanical fan and the aux fan have both been removed on my car, and replaced with a single OEM electric fan. So far so good. No wiring, no fitment issues, nada. Plops right in, plugs right in, and works.

Part # 17-11-7-561-757-M14
Cheapest place to buy: Pelican Parts - Click for direct link
Price: $253.00
Why?: Because a good aftermarket electric fan costs $150+. This is $100 more, and it's a direct plug-n-play.


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#2 ·
Ken,

I could told you this work :D Glad you go this all worked out...

-TrippinBimmer
 
#5 ·
hmm.. so no need for a diff thermostat like the e36s? awesome!

i already have an electric fan, but now im going to try and push the use of electric fans upon all my auto friends even more!
 
#9 ·
Wondering the same thing... I realize it means less parasitic load on the engine but is it enough to make an appreciable difference?

Can we get more details on the install? I've been thinking about this and the price is fine with me. But I'd also like to know if it's something I can reasonably do myself or will I wind up paying more to have a shop do the labor.

Thanks!
 
#18 ·
That I'm not sure about.

That's really cool. Thanks!

So I guess the electric fan is on all the time? Did you notice any improvement for engine performance? Such as freer rev? :4ngie:
It's on when it needs to turn on. The only noticeable change is the car is a little bit smoother at low RPMs. Other than the obvious not-overheating part of it.
 
#21 ·
This just happened to me on my Z3. While attempting to change the thermostat, I turned on the car, and the fan exploded. Luckily for me, the hood was up so a blade ended up taking out just a grill (and my radiator and belts :roll eye )

So now I'm looking for a conversion to a electric fan. I've seen people remove all the fan (aux and clutch) and run a powerful SPAL puller fan on the factory Aux harness.
 
#28 ·
Ok you need to clarify as I am in the process. Heres the issue, my car has BOTH aux fan and mechanical fan. Im taking out the mechanical fan just becuase the blades are broken and cost of replacment equals new electric fan.

Putting in the new electric fan is easy as pie, but where do you plug it into? I beleive the spot you plugged yours into is where the AUX fan used to plug into, well i still go minez. Or do you think im safe just taking out the mechanical fan and relaying on the AUX fan?



(Reason why I dont want to only use my AUX fan is becuase BMW put in a mechanical fan for a reason, extra cooling is clearly intended. If the aux fan could have handled it, they wouldnt have added the mechanical fan)



Sorry for the chicken scratch, but Im in a mess here.
 
#37 ·
Although the OP post is somewhat interesting it is severely flawed and frankly ill advised.

1) Removing the AUX fan just so he can install the intercooler is a mistake at the expense of his tranny. The AUX fan on the automatic transmission is design to kick in when the clutch fan is insufficient at keeping the engine in the normal operating temperature.
When your engine temperature is in the middle it reads between 167°-235.4° F. There is about a 68 degree variation between what is normal. Anyhow, when the OP engine was overheating, he was overstressing both his engine and transmission because it means that the temperature was above 235.4F. Since the automatic transmission used the engine coolant to cool down (via the tranny heat exchanger), this means that the OP's tranny was being over stressed. Any temperature above 200F will decrease the tranny lifespan and I am sure the OP just decreased his tranny life. His tranny is going to die soon.

2) The reason why BMW only install a clutch fan (ie mechanical fan) on its automatic cars is because they want to keep the tranny in its optimum operating temperature. The clutch fan is working to keep the coolant below 200 degrees so that the auto tranny doesn't get overheated. Manual transmission doesn't have a cooler and does not rely on the engine coolant to cool itself so therefore they don't require a clutch fan.
 
#41 ·
Good information guys.

I'm definitely doing this, not sure when though. Like someone else said, probably won't be until I overhaul the cooling system. Hopefully that will be before it lets go.

Anyways, I'm thinking about leaving the aux pusher in the front, and installing another puller run by a relay on the engine side. I would probably set it to run on high or low anytime the ignition is on. I'm not a big fan of the temp controllers. This won't be the cleanest install, but I'm not sure I trust the single electric fan, like other have pointed out.
 
#46 ·
I agree with ///Flash, i also notice that the M3s manual and SMG have 2 fans also.
I think the machanical fan because of its placement and design, covers a wider area of the actual radiator, that mean, the bottom end where the tranny cooler is, will be effectively covered by the machanical fans cooling area.
The electrical fan, from what i remember is smaller than the mechanical ones, and does not cover the bottom corners of the radiator (tanny cooler section)

Based on what Nick has said, it seems its a case of overkill on BMWs part, which apprently isnt that much overkill since the fukers still **** themselves.
If anyone is worried about the tranny not being cooled properly with the electrical fan, an auxilary tranny cooler can be added. they can be bought fairly cheap top very expensive. My 6th Gen V6 accord had a similar rep as BMW auto boxes, and i did this to it, and that car is still running with the original transmission.

I think the M3s and autos can safely run electric fans, but as guys have said, its being done by BMW for a reason.
Now the question is, are the E90s and 1 series still using mechanical fans, do they have aux fans? Nick and Ken are both in humid muggy Florida, and running boosted cars, so i think if it works for them, the rest of you will be fine.
 
#47 ·
It's going to be fine.

Before doing this, I confirmed with several sources. One of which is Nick G, who I'm sure has done his research on it (as he has mentioned). He isn't one of the most respected BMW tuners without merit.

The car has not overheated or had any issues since swapping in the electric fan.
 
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