The e46 guys can remove their clutch fan and aux fan to replace with a single electric fan that utilizes controller and electrical supply for aux fan:
https://e46fanatics.com/forum/showth...9735&highlight
http://www.zhpmafia.com/forums/showt...)-doityourself
Would this approach work on the e31?
Last edited by bdiefAZ; 04-14-2019 at 09:08 PM. Reason: Title update
Regards,
Brian
Cave Creek, AZ
On the E46:
The electric cooling fan is controlled by the ECM. The ECM uses a remote power output final stage (mounted on the fan housing). The power output stage receives power from a 50 amp fuse (E46 - located in glove box above the fuse bracket). The electric fan is controlled by a pulse width modulated signal from the ECM.
On the E31 (at least my 1991) the aux fan is controlled by a simple thermo sensor switch on the side of the radiator near the expansion tank. There are three leads into this switch: Ground, High Speed and Low Speed. The Low Speed is run through a big resistor on the side of the Aux fan (no PWM). The circuit is only energized when the A/C is on.
I have converted my E31 to electric fan. I used a two speed fan and built a controller with separate sensors for each speed located on the lower radiator hose. I'm still tuning it, and will be posting a description soon.
Here are two threads addressing the subject:
https://www.bimmerforums.com/forum/s...ght=nevadaMike
and
https://www.bimmerforums.com/forum/s...ght=nevadaMike
Another question:
The aux fan on the e31 is triggered either by the AC system running or a temperature switch in the radiator and has 2 speeds. Would it be possible to run a larger fan as a puller (more efficient) with this dual purpose setup and use existing wiring from the aux fan? I have the lower temp switch installed in my radiator to trigger the aux fan to help when cooling needs are present. Is there something that I am missing?
Sorry for the repeated/re worded question, I am not the electrical expert!
Regards,
Brian
Cave Creek, AZ
An electric fan sounds like a good idea - until you realise that you are swapping a belt-driven, thermostatically controlled mechanical fan for a belt-driven mechanical alternator (along with its inefficiencies) connected to an electric motor (again, with its inefficiencies) which, in turn, is connected to a mechanical fan.
As long as you just pootle around in your E31 an electric fan will do just fine - but, with a great lump of engine and the huge amount of heat energy it can generate (and being quite inefficient it will produce a reasonable percentage of its output power) an electric fan is not going to cope.
The viscous-coupled fan is perfectly suited to the job - it sits there idling away when not needed and then uses a proportion of the engine power to move air through the radiators - exactly what is required for the job. If you think an electric fan will take no power from the engine then you are wrong - it takes it via the alternator through two sets of inefficiencies.
Modern BMW's don't use a belt-driven fan, they use brushless, electronically controlled motors driving an efficient fan on a powerplant that is so much more efficient and produces a lot less heat!
Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i
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Update:
I have been experimenting with fan modifications lately, have modded 2 e46's to the single fan mod with great results. Details here (not my writeup):
http://www.zhpmafia.com/forums/showt...)-doityourself
On the e39/e31 front, I have swapped out 2 fans recently, one on m62Tu e39, and the other on an M70 e31 with the following fan from later model 7 series and X5 with mechanical fans:
Fan Blade 17417504732
Fan Clutch 17417505109
Attachment 643851
This fan blade and fan clutch must be used together.
The new fan is quieter, potentially less prone to breakage, and moves more air. The fan installed on the e31 M70 is under-driven with 109mm pulley and pulls more air than stock fan setup with stock 97mm pulley. This is early in testing, but so far, working well. I am not suggesting that we all go out and change our fan blade/clutch, just proposing a potential upgrade when doing maintenance. Comparison photo showing the difference in blade design.
IMG_3944.JPG
Here are some photos of the fan on the M70 car as you can see same clearance and offset from water pump as the original:
IMG_3713.jpgIMG_3715.jpg
Fan fitted to M62 Tu e39 shown here:
M62 Tu fan upgrade.jpg
Hope this helps.
Last edited by bdiefAZ; 04-03-2020 at 10:09 AM.
Regards,
Brian
Cave Creek, AZ
Update on the fan modification to the e31:
Fan Blade 17417504732
Fan Clutch 17417505109
(This fan blade and fan clutch must be used together as an assembly)
I installed this fan on the e31 M70 with an under-driven pulley of 109mm pulley vs. the stock 97mm pulley. 500 plus miles on the mod so far, with temperatures ranging from 35 to 85 and all is working well. Gas mileage is up, recent computer reading shows 19.2mpg, previous average was 18mpg.
The under drive pulley is: 109mm pulley from early M70: 11511709872, you will need belt 5Kx1165 11281736698.
Last week, I installed one of these fans on a 1997 M62 car as well, that car has been performing very well too with 350 miles on it since the modification. We will monitor the performance on that car, but I see nothing negative so far.
I will keep posting results, July will be the ultimate test.
Last edited by bdiefAZ; 04-03-2020 at 10:09 AM.
Regards,
Brian
Cave Creek, AZ
Interesting for my M73, I just searched pully sizes on RealOEM, the regular size is 105mm however hot climate/gulf and J-Spec cars got the 93mm. Ill check with mine since its a gulf car
"Understeer is when you hit the wall with the front of the car, Oversteer is when you hit the wall with the rear of the car, Horsepower is how fast you hit the wall, Torque is how far you take the wall with you."
This mod has been great, I have driven the 850ci a total of about 1000 miles since the mod, I have also installed the upgraded fan on other e31's and e39's, including M62, S62 and M70 cars here in AZ.
The e39 M5 was the semi daily driver over the summer with the same upgraded fan/fan clutch. Sometime during the summer the M5 lost its auxiliary electric fan and did fine with the upgraded mechanical fan here in AZ.
Regards,
Brian
Cave Creek, AZ
that IS intersting and makes sense to me now.. many moons ago, my belt broke and water pump broke and so did the pully on my 03/90 build date Japan model car and my mech at the time, said he was having a hard time trying to find the same size pulley so he had to buy a smaller one and therefore buy a different belt. I kept the belt packaging and funny enough just the other day I was looking at it, tho I never knew exactly what pulley size the mech bought. Now I wonder if he had to buy the smaller pulley from WorldPac (I know that is his parts supplier, at least). I had to buy a new fan and fan clutch then too and if I recall it was kinda costly.
If the M62TU fan blade/clutch combo is cheap, I may just grab one for shits and giggles.
EDIT: I bought a used fan clutch and blade matching the parts numbers above from a 760, which had a Behr Hella sticker with date 2015-02-03, so I'm assuming it was replaced in 2015 or more recent and it was about $150CAD on ebay. Looks very good condition with no oil spilled on it but just some dirt.
Last edited by clockwork; 12-02-2019 at 05:07 PM.
I swear, my cars are like a girlfriend.
Sometimes its a rough ride, sometimes its smooth motorin'.
Sometimes she doesnt like how i treat her and sometimes i dont like how she behaves.
BUT at the end of the day, she loves it when I am inside her.
Hmm, very interesting. I do not have any overheating issues even after very spirited driving but this upgrade might benefit me still.
More efficient airflow with less drag on the crank will be helpful, my crank is already dragging an 8 rib supercharger belt!
Any idea if this will work on the M60 840?
It will work on the M60 car as well.
Regards,
Brian
Cave Creek, AZ
This sounds appealing. I love upgrades that use OEM parts. For the M60, can I get away with just the fan blade and clutch or do I need a different belt and pulley?
I have ordered the parts, the under drive pulley for pre 1991 M70 was the most expensive part, $150!
Should be able to do the upgrade on the weekend and report back...
Last edited by dragon850; 11-13-2019 at 02:58 PM.
this belt length of 1165mm is based on the fact that your car does not have a second alternator, by AC Compressor...
the belt should be the 5k x 1180 (for car with second alternator) or 5k x 1190 (for car with second alternator and AC Compressor pulley) (according to Rock Auto details).
I just realized this, so now I have three to sell
keep that in mind.
Sent from my Nexus 9 using Tapatalk
Last edited by clockwork; 12-06-2019 at 11:23 AM.
I swear, my cars are like a girlfriend.
Sometimes its a rough ride, sometimes its smooth motorin'.
Sometimes she doesnt like how i treat her and sometimes i dont like how she behaves.
BUT at the end of the day, she loves it when I am inside her.
So I finally pulled the trigger on doing the refresh yesterday only to realize my mech 10 years ago put the 109mm pulley ON there BUT used a wrong sized belt. he out on a 1205mm belt which is 15mm longer than the 1190mm option BMW recommends for my Japan edition car with the second alternator and A/C compressor. So that was good to see that I already had a 109mm pulley even tho I have a spare used 109mm pulley for sale now (figured I may as well put the new one on since I had the used one off at this point), I at least checked out all other belts, installed proper belt and also swapped out the 3 end hose that extends from top of coolant reservoir to other side of rad and the other end connects to engine block beneath the oil filler spout.
I'm very much happier about the look of the newer fan blades in the rad cover. Tight in there but NO chance of anything striking. The perimeter ring makes it just look much larger, but it is not. It may be taller but that pushes it towards rad more, yet not striking it or anything .
I look forward to getting my recapped GM from EEE Degree to Drive so I can start my girl up and see if it makes a difference or if it just looks nicer
Quite a fan blades design change tho...
Sent from my Pixel 3 using Tapatalk
Last edited by clockwork; 01-06-2020 at 10:40 AM.
I swear, my cars are like a girlfriend.
Sometimes its a rough ride, sometimes its smooth motorin'.
Sometimes she doesnt like how i treat her and sometimes i dont like how she behaves.
BUT at the end of the day, she loves it when I am inside her.
Curving the blades makes them physically longer, so they move more air. This is genius.
Desecrator of all things Sacred
We have done this same upgrade on my friends 850 with the parts I purchased for my car, but later realized I would have to remove the supercharger to change the belt so I decided against this till I do some sort of SC maintenance.
Worked out great and he is very happy with this upgrade!
Something I will have to look into.
What exactly is the part list to do this conversion?
I am glad to see others doing this mod!
Regards,
Brian
Cave Creek, AZ
So we did this upgrade on friends car just now but the 5k x 1180 belt was still just too short! I ended up using smaller tensioner pulley to make it fit but even so it was an incredibly tight squeeze!
What am I missing here? Is it possible this 1991 850 manual has a larger AC compressor pulley??
20200331_100926_resized.jpg
Last edited by dragon850; 04-01-2020 at 04:53 PM.
You may need a 5Kx1190 belt, PN 11281736972, by the looks of the AC compressor.
Looking at RealOEM for the E32 with the 109mm pulley, and an AC compressor with the larger additional alternator capable pulley, 5Kx1190 is specced
https://www.realoem.com/bmw/enUS/sho...diagId=11_4611
I had the same issue
Regards,
Brian
Cave Creek, AZ
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