Mechanical Fan to Electric Fan Swap (Automatic's) doityourself

Yup, that's what I recall reading now. So, not strong evidence that it's a big impact, but every little bit helps. Let us know how it goes.

Will do...

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Originally Posted by WOLFN8TR

Found This...

The only big black question mark that was never understood was:

Why did the BMW Steptronic Automatic cars all come with two fans up until around 2006?

The possible answer or best anyone could come up with was the Steptronic Automatic transmission required some extra cooling hence the extra fan.
But the question still begs is why did BMW abandon the fan in 2006 with the advent of the E90 and the E60 M54 engine facelift? Did they realize the extra fan was not required?

Terraphantm a while back found some pertinent information relating the relevance of having a second fan to regulate transmission temperature since M3 cars all have the two fans.

But that discussion was not followed up because candidates doing the swap are not doing it on an M3.

As for M54 engine transmission cooling and long term effects I can't say.

Kpeng is the only member I know whom has driven with this mod in his car the longest and he has driven his car daily for a number of years in the hottest/most humid place in the USA (Florida). Another member has driven for over a year in Phoenix Arizona, the hottest/driest place in the USA, with this mod and had no issues.

Both claim that they had no issue with engine temp or tranny temp in all that time so based on their experiences I don't think it will be an issue for anyone living and driving in cooler regions.

The AC compressor is not driven by the fan but it is driven by the fan belts. In theory the AC compressor should perform slightly better because we are removing about 5+ lbs out of the belt drive system when we remove the mechanical fan.

Said and done the entire DIY is 1000000% reversible if after a couple of days you find your car is going bananas. Even if you can't return/refund your electric fan after changing your mind you can sure sell it on eBay for easily what you paid for it.

Also the DIY pays for itself when you sell your old mechanical fan and aux fan assembly. Both on their own each are easily worth $75 to $100 and carry a high demand.
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Newer cars have more powerful fans.

Z4 automatics and Z4Ms have 600W fans. Z4 manuals and E46 non-M manuals have 400W fans. The even newer cars like E90s and E60s have 800W and 1000W fans. Maybe more for some models. Presumably that extra 200W+ eliminates the need for the aux + mechanical fan combo. BMW probably felt the automatics needed the extra capacity because of the transmission cooler.

Realistically, as long as you don't live in an area that reaches extreme temperatures (Saudi, Arizona summers, etc...) you're probably okay with the 400W fan.

Some E83 X3s also had a 600W fan available and its shape is closer to the stock E46 fan. Might be a good alternative for automatic cars (and even S54 cars)

That's good info. How many watts are the 2 fans on our cars now? Also, you're saying you can get a mechanical fan from an E83 instead of the one Gary's talking about and it's a direct replace?

Good info...

The one disadvantage of a Mechanical fan is at idle. It only spins as fast as the RPM's of the engine. That's why you always hear the Aux fan kick in. I did this Mod on my old Chevy truck and it was the best upgrade I ever did. One of the biggest reasons I believe this is a good mod is the fact that when the Mechanical fan decides to grenade on you it takes out alot of things with it. I've seen several guys post photos of holes in their hoods, trans coolers, radiators, expansion tanks all destroyed.

I'm shopping around right now for a good price on a quality fan. Once I get one ordered I'm going for it.

BTW- If you read the DIY links for E46 Fanatics several guys that live in Arizona, Florida and Texas have done this Mod years ago with No overheating or tranny issues.

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Originally Posted by johnrando

That's good info. How many watts are the 2 fans on our cars now? Also, you're saying you can get a mechanical fan from an E83 instead of the one Gary's talking about and it's a direct replace?

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Well watts in this case is referring to power consumption (electricity), so the mech fan isn't assigned such a value. X3 fan is electric. It looks like it would fit physically, but the connector is slightly different. Seems like the connector can be transplanted from the old fan though.

Again, unless you live in an extremely hot climate, it's unnecessary I think.

Makes sense, thanks.

Quote:

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Originally Posted by WOLFN8TR

Found This...

The only big black question mark that was never understood was:

Why did the BMW Steptronic Automatic cars all come with two fans up until around 2006?

The possible answer or best anyone could come up with was the Steptronic Automatic transmission required some extra cooling hence the extra fan.
But the question still begs is why did BMW abandon the fan in 2006 with the advent of the E90 and the E60 M54 engine facelift? Did they realize the extra fan was not required?

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My guess would be that the automatic transmissions add more heat to the radiator so additional cooling is necessary. The E90 probably has a different radiator and enough cooling capacity as is.

Attachment 7485

Just ordered the BEHR Fan off Amazon, $194 with Free Shipping. Plan on doing it this weekend!

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