Delete E39 engine fan?

[MartMX]

Ok, basic question: Why does the E39 have an electric and engine driven fans? My Toyotas just used the electric fan when needed.
Is the E39 electric fan enough by itself? Can the engine fan be removed for better gas mileage?
Let the answers/daggers fly...

[edjack]

The aux fan is just that: it aids the mech fan. In most scenarios, the aux fan will not deliver sufficient air flow by itself, esp in your neck of the woods.

A number of users have fitted an electric fan behind the rad, in lieu of the mech fan. With thermostatic control, it can help lower noise and save a modicum of power.

Most Toyotas use a sidewinder engine, making it impossible to install an engine-driven fan.

[tptrsn]

If you do delete the mechanical fan, the 318i aux fan switch from Philly98540s thread is indispensable. Really makes a difference having the aux fan kick on a little sooner.

I agree though, I'd keep a close watch on things in Florida weather if I deleted the visco fan.

[djb2]

Most cars with electric fans would use a mechanical fan if the engine orientation would make it easy.

Running the power through a belt, alternator, speed control and electric motor isn't especially light or efficient. Once the design switches to a primary electric fan, the designer can take advantage of the flexibility in location, size, orientation and control. But it's not the first choice.

The mechanical fan also has the advantage of constantly moving air at minimal cost and wear. An electric fan is typically only run when the coolant is hot, which leaves an idling engine with stagnant pockets of hot air.

[computiNATEor]

I've seen and read about some people deleting the mechanical fan in favor of an E60 electric fan with some custom shroud work. The M54B30 in my 530i continued on into the E60 generation, and there are cooling fans available that plug directly into the factory auxiliary fan wiring. If memory serves, there are about 4 or 5 types of cooling fans for the E60s, from M5 fans that fit no other E60s to an 800W cooling fan for the twin turbo 535is. RealOEM has the nominal wattages for the various fans.

In my case, the factory DME (ECU) tune needs to be modified so the car knows to drive the PWM-controlled fan more aggressively. Nothing a little time poking around in the MS43wiki couldn't solve. Manual transmission E46s (including the 330) also only used an electric fan.

[geargrinder]

OK. This was super "hot" (wakka wakka) topic like 10yrs back.

A real guru pro guy who don't come around here anymore was firmly of the view that actually the factory Aux fan is 110% adequate for these motors, based on fact that BMW equipped cars that way in other markets with same engines, etc. I've come around to his viewpoint through pretty extensive experience with it. But its always a flame war when the topic comes up.

Here's what you're going to find for feedback on this topic:

• A vast majority 99% of people will have zero actual experience with this. Many will have opinions tho.
• A very few cheerful Aux-Only success stories running around happy as clams.
• A notable and vocal segment of angry true believers who are infuriated by the very suggestion and who will insist that it is madness and idiocy and goes against all ethical principles of god, man, and The Bavarian Way. None have them have ever tried it. They are just true believers. Some may hunt you down on the internet and doxx you and try to ruin your life. Because you are a bad hateful person. Burn the heretics! Kill their children so their polluted seed will not reproduce!
• A few sensible folks who recognize that it works, but still like the idea of "redundancy", therefore, either keep the mech fan, or, have added a 2nd electrical fan.
• A very very few other sensible people - generally in hotter climates and heavy AC users - who tried it and found the fan ran more and harder than they liked, so they joined the previous group as "works but because of duty-cycles I think 2 fans is better for me".
• MAYBE one or two stories where an Aux fan died and caused a stranding. I'm not aware of any full on "Aux fan died and killed my car" stories (OK - at least none involving 'Visco-deleters'... cases of "mech fan puked and then I discovered the Aux fan was dead because it never ever ran and was seized up... and before I knew it..." there've been some of those I think...)

Here's my experience:

• I have run Aux-fan-only, on an M62TU with a supercharger fitted, for something like 4-5 years.
• I turn the AC on when I want. I drive in 90s and triple-diggies in summer when I have to.
• Engine is not assploded. Engine is great.
• The one (maybe two?) problem events I have had have been - get this - have been WINTER RELATED. Once (maybe twice?) slush has frozen up on the front of the car in freaky winter storm conditions, and caused the Aux fan to freeze up while driving at highway speeds (fan doesn't run over 30-40 mph so it can get frozen while driving in those weird conditions). THAT then caused me to start to go into the redzone whe I slowed down into stop and go traffic, and have to pull over, and figure out WTF why was I overheating in a blizzard.

Here's my bottom line take on the whole deal:

• It is 100% totally fine, mainly if you live in moderate / 4-season type climates.
• Realize that NO FAN IN THE WORLD does anything after 30-40mph roadspeed. I don't care if its 110F and the AC is set to "make ice", the fan is not doing a thing. The fan is only there for when you slow down or sit. Which is important, but lotta the haters are unaware of this fact. In the facelift type DME's , the DME shuts the fan off when you hit that speed in fact...
• "Fan was not made to run this MUCH!" is BS. Those same exact fan constructions are used for cars with only an electric fan. Only a zillion OEM cars are running around with single electric fans these days. That's how they do it now. Redundancy is NOT an absolute requirement, and the Aux fan quality and durability is amazingly high.
• If I DID live in a superhot AC-year-round and 100's-all-the-time-in-summer place, NO I would probably not do this, YES I would probably keep 2 fans. Mech and/or electric, one way or another (prob I'd go 2 electric... that was my original plan and I have a fan controller and everything on the shelf...) Indeed at that point just personally I probably would want the redundancy just in case. NOT for 'engine protection' by the way, but just purely for 'stranding inconvenience' purposes.
• If you're talking about facelift motors, the Aux fan is driven by PWM by the DME. This means your tune can be tweaked to trigger it at different points. While it works anyway without this, it is MUCH better since I loaded Terraphantms tune tweaks that adjust trigger points. I highly recommend this for fan-deleters. Otherwise the fan comes on a bit later but then has to run at a higher duty cycle (sudden high-fan instead of early-low-fan). Factory still works, this is just better.
• If you want to do this, you DO probably want to evaluate the lifecycle point of your Aux fan. That's one place I may be living on borrowed time. (original 2002MY fan still chuggin!)
• You also might want to fiddle with custom coding the temp gauge behavior in the cluster so it moves more, just so you can feel safer about temp monitoring. I mean I just think this is better anyway, the factory cluster has this "keep the needle straight up so Suzy Housewife doesn't ask why the needle is moving and is it a problem" buffering thing...
• If you are running a lower-temp M62TU thermostat, which is a good idea really for all kinds of reasons, do realize this increases cooling system duty not the other way around. Some guys think "oh lower t-stat means it won't be as hard on the fan", really its the opposite, you're cooling the engine more. This is still fine, just heading off erroneous logic there. I run non-MAP, mechanical lower temp t-stat (again w/ Terra's tune tweaks) and it runs brilliantly with the Aux fan only and PWM tweaks.
• I love the stupid mech fan being out of the way in the engine bay. Particularly helpful w/ the supercharger belts etc. You can get a cute little beauty cap to cover the threads from BMW (because duh they sold cars w/ no mech fan...) that is a nice little engine bay add-on.

In some exceedingly rare scenarios, the aux fan will not deliver sufficient air flow by itself

FTFY.

esp in your neck of the woods.

Truth to that however.

If you do delete the mechanical fan, the 318i aux fan switch from Philly98540s thread is indispensable.

Yes that is the "non-TU" solution for fan deletes, definitely the way to go there.

But for a TU, you fix it (in a better way actually) via the PWM coding....

I'd keep a close watch on things in Florida weather if I deleted the visco fan.

Again, agreed.

In my case, the factory DME (ECU) tune needs to be modified so the car knows to drive the PWM-controlled fan more aggressively. Nothing a little time poking around in the MS43wiki couldn't solve. Manual transmission E46s (including the 330) also only used an electric fan.

Exactly ^^^. I doubt if swapping the fans from other models is really changing the construction quality at all from the E39 one... But... if you ARE in AC-all-the-time areas... sure, whack a second fan in there for security purposes and extra-cold AC...

[tptrsn]

Some one of the young guys on here who is super into his E39 should start making a G.O.A.T. list of comprehensive answers to FAQs for the forum, and start with this one and a bunch of other GearGrinder volumes. Well done my man!

[killian665]

I just don’t see the point. I guess it could save you 7 seconds having to pull the fan off to do anything on the front of the engine in the future but that’s about it.

[tptrsn]

That's just the beginning of the list of benefits for many of us. To each his own.

[geargrinder]

I just don’t see the point. I guess it could save you 7 seconds having to pull the fan off to do anything on the front of the engine in the future but that’s about it.

Well, yes and no. Don't get me wrong - I NEVER advocate for people to do this. But if asked... that's the low down.

Couple extra bits:

• OK bruv. Not 7 seconds. Hyperbole is fun, but, taking the fan off is at least "minutes" and is a PITA getting around the shroud etc. unless you take the shroud off - even more time... SO yeah. You're right. Not a huge deal. But also. Its more hassle then "7 seconds" Get the special holder tool out. Blah blah. It takes 7 seconds to walk over to pick up the wrench. 7 minutes? Probably closer, IF it all goes smoothly. Doesn't count wrestling it past the shroud and for sure doesn't include taking off the shroud. I hate taking the fan off. Eff that stupid fan. Just IMO.
• For S/C setups like mine uniquely, the space is even more limited, and maybe you want to get in there even more often. SO, more benefit for me for sure.
• Some other people have even more custom weird crap in their front engine bays requiring even MORE space up there. For them people its a real perk.
• The visco fan DOES assplode sometimes. Plenty of 'cut rad hoses' and 'blade through hood' pics of E39's to show this. This honestly was one of the main logics to the delete BITD.

[djb2]

\[*]A vast majority 99% of people will have zero actual experience with this. Many will have opinions tho.

That's certainly an exaggeration.

I have removed the mechanical fan from my Z3. It's a light car with a manual transmission. Plus a fan blade through a Z3 hood would be an expensive disaster.

I feel it's needed on the e39. It's a much heavier car with an automatic transmission. Plus the fan shroud is much stronger, and even if a blade got through replacement hoods are plentiful in the boneyards.

[tptrsn]

I feel it's needed on the e39. It's a much heavier car with an automatic transmission. Plus the fan shroud is much stronger, and even if a blade got through replacement hoods are plentiful in the boneyards.

There's that opinion thing.

Many of us can tell you from experience that it clearly is not "NEEDED." Many people feel better with it on the car though. You seem to be one of them.

[computiNATEor]

Well, yes and no. Don't get me wrong - I NEVER advocate for people to do this. But if asked... that's the low down.

Couple extra bits:

• OK bruv. Not 7 seconds. Hyperbole is fun, but, taking the fan off is at least "minutes" and is a PITA getting around the shroud etc. unless you take the shroud off - even more time... SO yeah. You're right. Not a huge deal. But also. Its more hassle then "7 seconds" Get the special holder tool out. Blah blah. It takes 7 seconds to walk over to pick up the wrench. 7 minutes? Probably closer, IF it all goes smoothly. Doesn't count wrestling it past the shroud and for sure doesn't include taking off the shroud. I hate taking the fan off. Eff that stupid fan. Just IMO.
• For S/C setups like mine uniquely, the space is even more limited, and maybe you want to get in there even more often. SO, more benefit for me for sure.
• Some other people have even more custom weird crap in their front engine bays requiring even MORE space up there. For them people its a real perk.
• The visco fan DOES assplode sometimes. Plenty of 'cut rad hoses' and 'blade through hood' pics of E39's to show this. This honestly was one of the main logics to the delete BITD.

The annoying removal is the main reason I’m researching the E60 fan conversions. On the V8 cars there is loads of room vs the I6, where it is a complete and total PITA that has me cursing the BMW engineer who dreamed up this hell.

I’ve also had fans explode (thankfully without taking out the hood), and it’s not nice to put it mildly.

That's certainly an exaggeration.

I have removed the mechanical fan from my Z3. It's a light car with a manual transmission. Plus a fan blade through a Z3 hood would be an expensive disaster.

I feel it's needed on the e39. It's a much heavier car with an automatic transmission. Plus the fan shroud is much stronger, and even if a blade got through replacement hoods are plentiful in the boneyards.

The mechanical fan will definitely go through the fan shroud, from first hand experience.

It’s also worth noting that a mechanical fan will always cost a few hp. Electric fans are far more efficient.

[geargrinder]

That's certainly an exaggeration.

Oh it most definitely is not. You think > 1% of E39 owners have tried fan delete?
Absolutely no frackin way.

That's probably an over-statement actually. It's more like 99.9% of E39 owners I bet.

But this is why I hate these threads.

I'm not arguing everybody should do it. Not even remotely. There's pros and cons.
If somebody says to me "I strongly prefer the peace of mind that comes from knowing I have redundancy", totally fine, COMPLETELY respect it.

Sadly the haters have to insist "OH NO NO WAY THAT FAN CAN DO THE JOB".
Would be nice if the haters had the tiniest bit of objectivity to recognize facts vs their judgement call and respect that not everybody has the same needs/priority.

"NEEDED" is definitely incorrect, as I say, excepting unusual circumstances.
Short of unusual circumstances, the Aux fan EASILY keeps up w/ rad cooling needs of the M62.
Claims otherwise are factually erroneous.

Unusual circumstances might include:
- Heavy trailering with AC on
- Heavy tracking WOT
- Heavy creeping traffic in triple digits w/ AC on

But I can tell you right now, it has to be pretty extreme. I drive my car plenty hard on the street tho' and the old aged Aux fan - in 4-5 years - has NEVER failed to keep up.

[killian665]

I don’t think I’ve ever spent longer than maybe 15 seconds taking the fan off. Maybe yours gets corroded because of where you live idk. That’s putting the wrench on it, tapping it once, and pulling it past the shroud lol.

As far as the clutch exploding I am firmly in the camp that that only happens when you neglect it. I had my clutch lock up on me and just stuck solid. Whined like crazy when you gave it gas since it was matching true engine speed. Replaced it same day no issue. A week later same thing happened to my 840, same result, same repair. Neither exploded.

Same exact thing with my friends M5. I think they only explode because they go bad and people drive around for a week with it locked up then wonder why it finally let go.

[geargrinder]

All respect, cuz normally I do respect your posts, I guarantee that's still BS bragperbole. It doesn't fall off in your hand with "one whack". That's totally stupid to suggest even 15 seconds really. You do know what seconds are right? And if you never have ever had to use the counterhold tool , you aint worked on normal old BMWs bro. I seriously want to show up at yer place w a normal typical car and a stopwatch and laugh hysterically as you pass the 5 minute mark and start trying to assplain the excuses... and it ain't a winter/climate thing BTW.

- - - Updated - - -

Ha ha I posted before the "5 seconds" got edited to "15". Too bad I didn't quote it. 15 is still bragperbole.

[computiNATEor]

Try removing the cooling fan from an I6 E39 in less than 15 seconds. Ain’t gonna happen.

Grinder, with your mechanical fan delete, have you modified the shroud at all?

[XAlt]

I went aux only on the 110C stat and never really looked back

[djb2]

The mechanical fan typically fails just a Southwest engine -- breaking off at the root, and throwing blades through the shroud. You can collect the blades later from the under-engine splash panel. The e39 fan shroud has a good chance of containment, with substantial damage.

We live at the near the top of a long steep hill. I was tipped off that something was wrong when the electric fan would continue to run after the engine was shut off. Clearly it wasn't keeping up with the cooling. Replacing the broken fan with the one removed from my Z3 fixed the cooling problem.

[geargrinder]

Grinder, with your mechanical fan delete, have you modified the shroud at all?

That's a bit of a long answer, and relates to the SC.

I have an M5 shroud because I was hoping to toss that on to replace the 540 one, because the M5 exp tank is nicer, and I was hoping it would give me more clearance around the SC belt tensioner. However it was a real tight fit and I wasn't able to pull it off easily. I still think maybe I could make it work... next time I have the front all apart I may try again, this time being willing to make some cuts/mods.

But I have been thinking about slicing the factory shroud up, taking off the 'ducting' part, so that all is left is the outer frame and the bit that holds the Exp tank in place. The benefit of course would just be access and ease of pulling shroud / exp tank. I think somebody else just did that (slicing off the left side of the shroud)(left side as in proper left-side-of-car, 'right side from the front')

If you go dual electric push-pull, of course you NEED a shroud still, to keep the air flowing through the whole rad. There's a ton (I'm sure you've seen) of good examples of fabbed metal shrouds for guys who went dual-electric, the $$$ Zions option isn't the only one, there's some good adapted Summit/Jegs type deals too... Those examples have made me think I should just fab a metal exp tank mount for the right side... but I don't have access to a sheet metal brake anymore, and sheet metal work without a brake can often come out real crappy. You can do tricks like angle-iron-in-a-vice (ghetto brake) but more work than is worth it for the purpose.

[sienayr]

Here's my anecdote. I've had the fan off over the winter, I took it off to do something and didn't put it back on. Last night after my wife got home, I got the dreaded "the car is doing weird things". Description sounded like transmission problems; she said the SES light did not come on. I jumped in the car, turned on the key and immediately saw that the temp gauge was up in the red. I turned the car on and the aux fan was running. Shut off car, ran and grabbed the fan, spun it back on and went for a drive to get it cooled down. Luckily everything ran fine, no evidence of coolant/overheating, and everything was still fine this morning. Ambient temperature was mid- 80s and she was running the AC. I guess it must have gone into limp mode, that's the only thing I can deduce from her description of what was happening. Anyhow, no more fan delete for me once it warms up. And my wife now knows to check the temp gauge when s**t starts going haywire

[killian665]

I’ve taken at least 300 fans off and never once used a counter hold tool. It doesn’t take any time at all really. I’ll make a video of me taking it off my car in 15 seconds to prove it to you. I6 cars is no different just a little extra for the shroud. 2 fasteners and pull it out with the fan. I think all the complaining is from people who don’t work on them all the time

At most I had one fight me because the thing was so worn the nut wouldn’t spin by spinning the blades so I had to wrench the thing off the threads instead of spinning it with my hand. But to take longer than a few a seconds on a V8 car or longer than a minute on an I6 aside from the one? Never.

[computiNATEor]

So all your fan clutches are seized. Got it.

[djb2]

Just wait until #305 takes you down.

I never had more than a minor problem, until I did. We had to make a holding tool from 1/4" steel plate. I've not needed it since, which is good because I left it with a friend when I moved.

I still have a forged 1-1/4" wrench in the tool chest, but typically just need to use a stamped bicycle wrench.

It was one of those times when I realized that sometimes others have had a different experience. "Oh, so that's why they were bitching."

Reassembly is always with anti-seize and no more force than the momentum from spinning the fan.

[geargrinder]

Siena I wonder if your aux is dying or intermittent. Of course the facelift auto has that not-hugely-robust heat exchanger thing. The thermostat in that actually could be going bad for you?