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Thread: Spal Electric Fan Conversion DIY

  1. #1
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    850i, Z3 2.3, X5 4.8is

    Spal Electric Fan Conversion DIY

    I thought I would make a DIY here for people looking to make this conversion. I participated in an earlier thread on the subject, where MWrench did this mod I believe. There was some information about it, but not enough for me. I ended up getting a more concise set of instruction through several E36 and E39 threads, and thought I'd make an area on here.


    The Reason: I had read a few threads about fans blowing up and destroying the rad, denting the hood, etc... I already had a nick out of each fan blade due to some contact earlier in it's life, and figured that it could be beneficial for the belt drive and water pump pulley in some small way to boot. Whether or not it frees up some small amount of HP seems to be a matter of debate.

    The Parts: After much reading I ended up going with a Spal puller fan, and I chose the 16" high performance version with the curved blades. THIS IS A SINGLE STAGE FAN! You can click the following link to read up on the fan stats:

    https://webstore.spalusa.com/en-us/p...-16-c-12v.aspx

    I bought it off Ebay for about $135 + shipping.



    I went to Summit racing and bought the following accessories:

    - A 195 degree Spal wiring harness kit





    http://www.summitracing.com/int/parts/spu-ix-195fh

    - A mounting bracket kit. Super important because the fan doesn't come with any mounting material and it is too heavy in my opinion to simply attach it through the radiator

    http://www.summitracing.com/int/parts/spu-ix-30130011

    - A rubber fan shroud. Attaches around the fan housing and acts as a shroud/protection layer between the hard plastic fan housing and the radiator fins.

    http://www.summitracing.com/int/parts/spu-ix-30130074

    They also have a wiring kit to a couple of rocker switches if you wanted to be able to switch the fan on and off manually.


    The Job: After a couple of weeks wait everything arrives at home and sits waiting to be installed. The harness package comes with a temperature sending unit, so that you can add a housing to a coolant line (the bottom hose from what I read) and install the included sensor. I ended up opting to connect the harness to the existing coolant temp sensor used for the AUX fan, so the sensor, and temp specs for the kit didn't really apply since it would be coming on and off based on the stock sensor. I didn't take any pictures during the job as I wasn't thinking about doing a DIY until after, so my apologies.

    Step 1: Remove the skit plate under the rad, just the one piece with the rubber trimmed edge, And jacked the car up on all four corners (was doing shocks at the same time), to get under engine clearance.

    Step 2: I removed the clutch fan using clutch fan tools (a thin 32mm wrench and an equally thin locking bar with several holes for fan pulley bolts), super easy! I dropped the fan out of the bottom of the car.

    Step 3: disconnect the fan shroud push pins and screw clips (10mm bolt on each side) so that the shroud can move around a bit.

    Step 4: I disconnect all of the top little coolant hoses (3 clamped). You will need to seal off the small hose outlet at the top of the water pump, and the small hose outlet at the top of the radiator to prevent spillage (I just used some bits of rag). The return line to the reservoir is fine unsealed.

    Step 5: I wedged the electric fan into the opening of the stock fan shroud and placed it where I wanted it. The top of the fan should line up with the top edge of the radiator with the top fan edge matching the top layer of radiator fins. This will allow perfect fitting top to bottom in the fan shroud opening while ensuring that all fan surface is on radiator fins. For right to left you look into the opening and slide the fan back and forth until you have it centered in the fan shroud opening. Once done I used a marker and marked a line on the radiator lip to correspond with one of the fan cover bars that would be running top to bottom to ensure proper side to side placement; easy!

    Step 6: I removed the fan and then removed the fan shroud making sure to leave the reservoir in place. It's a wiggle job, and you need to go slow to make sure that you don't damage anything, but it will come up and out.

    Step 7: I lined up a top to bottom fan housing bar with the marker line I had drawn fro proper centering left to right on the rad, and I place the top edge of the fan housing to the top edge of the radiator fins and voila, the fan is in proper position!

    Step 8: The fan mounting brackets come in a package of four and click securely onto the fan. My radiator already had several mounting holes and so I manoeuvred each mounting bracket so that it would reach out from the fan housing and match up with a hole. You want to have the brackets stretch as straight away as possible from the fan to ensure a tight fit with no movement. I ended up enlarging the holes I chose with a drill to fit the bolt nut combinations I was using to bolt it on. NEITHER THE FAN, NOR THE BRACKETS, COME WITH HARDWARE!

    Step 9: I bolted on the top two brackets, and then used a dremel with cut off wheel to trim off excess bracket material as I wanted the fan shroud to fit snug along the top as before. For the bottom brackets I used two existing holes but this time used some larger thread screws since I would be able to get a nut on the back side. I measure the distance from fan housing and radiator mounting holes and dremel cut the two bottom brackets accordingly. The fan was now snugly mounted to the radiator.

    Step 10: Before putting the fan shroud back on I plugged the wire harness to the fan pig tail, and sorted out where I wanted to run the various wires. Spal instructs you to give the fan a dedicated power supply, because then fan draw is large I believe, so I would be using a post from the positive power terminal where the jumper nut is, and the alternator power cable goes (see picture, notice the new alternator cable I created that runs down the side of the wheel arch instead of in a metal tube along the engine. It's marine grade and sealed cable and a larger gauge than stock, the ground cable is larger and also of the same type of wire).



    The black ground wire from the pigtail is run to a 10mm bolt near the fan on the headlight pod bracket, and the red wire from the pigtail runs into the fan relay. I chose the location for the relay because there were already two holes from a previous owner's aftermarket alarm set up that I removed.



    From the relay I ran the yellow 12 v power wire to the terminal as described above, the red power wire runs back to the fan pigtail, and the little orange wire is looking for an ignition sourced power wire. You can run the fan off a constant 12v power source if you want the fan to run when the car is powered off. Since it is governed by the coolant temperature sensor it will run when the car is off until the sensor drops into the shut off range. The main issue here is that the fan has a rather large draw, so running it off the battery may run it down past acceptable levels. For my part I wired it to an ignition powered 12v source.

    Thanks to the help of a member on here I was able to source a ignition powered 12v source right where the relay was. The little black fuse box in the picture has four fuse slots when you open it. From the front of the car, the first slot is a permanent 12 v source (should you want that option) and the second slot is an ignition powered 12v source. Since there was no fuse there at all I simply pulled the connector out from the bottom of the box and attached the orange wire from the relay directly to it; done!



    The final wire is the grey wire. This one is to be attached to the temperature sender. For my install (after reading through the e36 and e38 threads) I decided to splice it into the existing temperature sensor. The sensor is on the opposite side of the engine bay from the rest of the fan wiring, but luckily the harness kit comes with more than enough wire length for each wire to do the job. I ran the grey wire along the top of the radiator and down the other side to the temperature sensor.



    There are three wires going into the sensor. The black is the ground wire, the green and black is the low speed wire, and the grey and black is the high speed wire. This sensor runs the auxiliary fan which is a TWO STAGE FAN, while the Spal is a SINGLE STAGE FAN. You have a choice here: ONE: you can wire the grey wire into the green and black wire which will activate the Spal fan when the coolant temperature hits the low temp threshold. At this temperature the auxiliary fan turns on to low speed as well. This wire is also responsible for turning the aux fan on to low speed when the A/C is turned on. The problem here from what I have reads is that if the Spal comes on as well it keeps the engine below the low temp which prevents the engine from running at apparently more optimal/efficient higher temps. Also, the fan is on far more often, and ostensibly not when actually needed.



    I attached the grey Spal fan wire to the grey and black wire which controls the high temperature setting and turns the aux fan on high speed. This means that the Spal fan will only com on when the coolant temp sensor hits the high threshold. This was the consensus choice from the E36 and E39 threads, but someone more knowledgeable can certainly chime in on the merits of letting the engine operate at a higher temperature before cooling.

    Step 11: I replaced the fan shroud by working the bottom edge over the fan and back into place behind the reservoir and in its retaining clips. This took some wiggling and flexing of the plastic, but it got back into it's home eventually. I then replaced the three coolant hoses and clamped them tight. Now time for the push rivets and brackets on each side. I topped up the coolant from the bit I had lost, and I was done.





    An observation I have made so far is that I have never seen or heard the fan come on! Ever! The car always warms up and the needle moves from blue to TDC and never wavers, but the fan also never seems to come on. The guys from the other forums warned that the fan is powerful and when it comes on it's generally fro no more than 30 seconds to bring the engine temp down a few degrees and then shits off again. Here in the spring, in the pacific northwest, it seems as though it's not hot enough yet.

    Still, I though it would be interesting to note that this set up moves from a fan running constantly, and the engine temp gauge sitting at TDC, to a fan that never seems to need to run, and the gauge is STILL at TDC. I have gone for reasonable drives around town with lots of stop light idling, and gotten out and not only is the Spal not running, but neither is the aux fan. This leads me to believe that the coolant temp is not even hitting the low temp threshold that would activate that fan, let alone the high temp threshold needed for the Spal. Pretty neat. I suppose it could be argued that the sensor is faulty, but with no code, no warning message, and no fluctuations in gauge temperature, I'm inclined to think that the system is doing it's job just fine, and that at least in this climate, the clutch fan is entirely unnecessary, at least in fall/winter/spring.

    Thoughts?
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  2. #2
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    Nice write up, will this also work in front of the condenser? Mine on the 840CI is about to go.

    And another thought if that fan is excellent and our cars run cool if all the cooling components are doing the job what about using that fan (the one in place of the engine driven fan) to run at say 1/2 speed tripped by the low temp switch and full speed when tripped by the high temp switch and eliminate the front electric fan.

    Seems that maybe he fan manufacturers may have improved their efficiency over the past 30 years. Thereby allowing one fan to do the job of two. Course you lose some redundancy.
    Last edited by 2001740il; 05-04-2016 at 03:21 PM.
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  3. #3
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    The high-speed operation of the auxiliary fan is for a situation where the viscous-coupled fan has failed to lower the coolant temperature effectively - OR - when the refrigerant pressure is too high. This is an emergency situation only, so probably the wrong place to wire the new fan. The fan would only run when the temperature gauge reached the 3/4 mark.

    The low-speed operation of the auxiliary fan is normally used by the A/C system to get additional air through the condenser. As your auxiliary fan doesn't run I guess that your A/C refrigerant pressure is too low and doesn't operate?

    Possibly a better way would be to add a temperature sensor to the lower hose on the radiator set to 70C - 80C and leave the rest of the system as it is. Even if wired to the low-speed contacts the fan would run at the wrong temperature levels.

    P.S. Excellent installation of the fan though!
    Last edited by Timm; 05-04-2016 at 04:52 PM.
    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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  4. #4
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    The one in front of the condenser is a pusher fan so you'd want to make sure the get that, but it is also a two stage fan so you'd need to get a fan that will run at two speeds based on temperature.

    - - - Updated - - -

    Quote Originally Posted by Timm View Post
    The high-speed operation of the auxiliary fan is for a situation where the viscous-coupled fan has failed to lower the coolant temperature effectively - OR - when the refrigerant pressure is too high. This is an emergency situation only, so probably the wrong place to wire the new fan. The fan would only run when the temperature gauge reached the 3/4 mark.

    The low-speed operation of the auxiliary fan is normally used by the A/C system to get additional air through the condenser. As your auxiliary fan doesn't run I guess that your A/C refrigerant pressure is too low and doesn't operate?

    Possibly a better way would be to add a temperature sensor to the lower hose on the radiator set to 70C - 80C and leave the rest of the system as it is. Even if wired to the low-speed contacts the fan would run at the wrong temperature levels.

    P.S. Excellent installation of the fan though!
    I'm pretty certain my aux fan comes on at low speed when I turn the A/C on.

    From my understanding the aux fan comes on low at 91 degrees and on high at 99 degrees. The thread where I got most of my information was from the M3 guys. The consensus over there is that the fan should be wired into the higher temp setting to come on at the higher threshold.

    http://www.bimmerforums.com/forum/sh...ring-DIY/page3

    I will continue to monitor the situation, but so far the temp gauge hasn't budged from top dead centre at all.
    Last edited by peezen; 05-04-2016 at 05:58 PM.
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  5. #5
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    You have tested that the fan actually turns on while the engine is idling and going above normal?

    Just leave it running and keep an eye on the needle or better yet if you have a way to measure (make sure) it does not overheat while doing this.

  6. #6
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    That's just it, the engine has not gone above normal temperature at all. Not while city driving, not while stopped at lights, not while idling at home. I will try the leave it idling for longer this weekend.
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  7. #7
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    Ok, so a few changes. I wired it to the green and black wire to have it come on at a lower temperature, but I'm finding that the fan comes on when the needle is a hair past centre, and will come on when I turn the A/C on

    BUT

    It will blow the 30 amp fuse everytime it comes on the second time, everytime.

    Can anyone think of why this is? The wiring is laid out pretty clearly in the original post. Any advice would be appreciated.

    I do plan to order an adapter and use the temperature sensor that came with the package to turn the fan on at 90 degrees, but until then I would like it to work!


    EDIT: I also have a Hayden fan control module with a blade temperature sensor that sticks through the rad, anyone have any experience with these?
    Last edited by peezen; 05-06-2016 at 09:10 PM.
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  8. #8
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    Hi, I envy you somewhat living in Victoria. I have fond memories from visiting twice. I have used the Hayden temperature sensor, and it does work well. In the end though I believe that a hose adapter with a probe that measures the coolant would be more satisfactory. Nice write up, and I have thought about this electric fan before. Could that fuse have blown because both fans came on at the same time? One of the first things I did to my car after replacing filters and fluids, and all fuel and vacuum lines was to change my plastic main cooling fan, and also the original coolant surge tank. I'm sure many of us are watching your experiment.

  9. #9
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    Thanks Mike, I'm originally from back east but this is home now

    UPDATE!!! So I have discovered that the fuse for the auxiliary fan AND the Spal fan are blowing when the Spal fan is attached to the Aux fan coolant temperature sensor.

    Looks like there is far too much draw on the same circuit, or something as the fans will start once and run, but the second time and both 30 amp fuses blow. From what I have read the fans have a very large draw to start up.

    THE FIX: I bought this:

    http://www.ebay.ca/itm/141638068422?...%3AMEBIDX%3AIT

    to go withe the 195 degree Spal cooling sensor. It goes on at 195 and turns off at 175 degrees F.

    THE TEMP FIX: I attached the grey wire that was attached to the temperature sensor to a ground attachment. With this set up the fan is an "always on" fan. With both fuses replaced they seem to run nicely on multiple start ups, and the Spal fan has not blown a fuse since. Though the fan can stay as an "always on" set up I'll be looking to throw in the adapter and sensor when it arrives.
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  10. #10
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    Yes, that's the sensible way to do it - with its own in-line temperature sensor so that you can get the coolant temperature within normal limits.
    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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  11. #11
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    As you also suggested earlier Timm Now, am I right to assume that the hose from the water pump to the rad on the passenger side it the right hose to adapt? Anyone happen to know the inner diameter?
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  12. #12
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    Yes, from the lower hose on the RHS (when viewed from behind) of the radiator
    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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  13. #13
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    thanks for this write-up. I've put this modification off for many years even with the proper parts.
    Perhaps this winter and with tihs discussion, I'll finally get it done.
    I swear, my cars are like a girlfriend.
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  14. #14
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    What i have done on an E30 project car with a M54b30 motor fitted was to move the sensor that is fitted to the radiator on the cool side of the radiator to the hotter side via a steel piece of pipe with a nut welded to it so the sensor will bolt in and the pipe is then fitted to the top hose where the water is at its hotttest
    i actually thought the fan switched on low at 95 deg c and panic mode at 105 deg c
    which to me seemed a little ludicrous as the coolant boils at 107 roughly and since it takes that measurement at the hot side god knows how hot the coolant is nearer the motor is it always struck me as a dumb place to fit that sensor but knowing bmw there is a good reason for it
    the main reason i did that was i had no room to fit the viscous fan any way with the newer motor i am of course curious why BMW fitted viscous fans rather than going electric anyway

  15. #15
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    Extreme Electric Fan Project

    1991 850i (e31), 6-speed, 155K miles. I have been following this thread and one on the 5-series forum for a couple of years. https://www.bimmerforums.com/forum/s...electric%20fan The 5-series thread is centered on using a two-speed 88-92 Ford Taurus 3.8L electric puller fan. rated at 2500 cfm (high range). Most of the posters source their fans from a junkyard. I got a new one from RockAuto for $70.

    For the most part I followed peezen's excellent instructions, along with the comments on the 5-series forum, with some exceptions: I built my own controller since the Ford fan draws 60 Amps on startup; I mounted the fan (with some modifications) directly to the stock shroud; and I got a severe case of "while-you're-in-there-itus." I decided to go with a complete cooling system rebuild: new Saleri water pump, all new hoses and clamps, new belts, tensioners and hoses, new radiator (less than $100 from Rock Auto) and new crankshaft position pulse generators. I didn't have any problems with my car but it was about time.

    Getting the old fan off was a bear, I bent my official BMW tool, so I welded up a tool out of 2" bar that went around the hub and caught 3 bolts. Still needed a 3' breaker bar on the wrench to get it off. The shroud came off, as well as belts, tensioners, hoses, water pump, etc. I had to move the hydraulic pump to get the bottom pulse generator off, so I disconnected the hydraulic hoses, so all the Pentosin bled out - might as well bleed the whole system, clean the filters, and replace all the fluid. I bought a case of 7.1 a couple of years back, so I had plenty. Everything went back together.

    Fan/Shroud Marriage:
    The stock shroud is pretty sturdy, (I checked and a replacement is $70 at RA), the Ford shroud is thicker and stiffer, so I figured if I mated the two it would hold up. The Dremel with a diamond blade made quick work of the flange around the ford shroud, along with a cutout to accommodate the expansion tank. I bolted the Ford shroud/fan to the inside of the BMW shroud after some test fittings to clear the shaft on the front of the water pump where the old fan was mounted. The Ford fan is smaller than the BMW shroud opening, so I made some sheet metal panels to block the openings, pop-riveted them to the assembly, and sealed them with some clear silicone.


    20171106_162057.jpg

    After everything was together used my Schwaben coolant tool to draw and hold a 20 lb vacuum in the whole cooling system with the heaters on full and the key at position II to get aux pumps on, and the heater cores open. Switched a couple of valves and about 3.5 gallons of coolant got sucked into the system. Started the motor and very little bleeding was necessary. Topped off the overflow tank.


    Controller: I've been using the "Desert Option"temp sensor on my radiator - 91º/96ºC vice the stock 95º/99º (I think) so I used that to control the two-speed fan. Picked up the signals (ground) at the sensor, and used a control relay plus a 60A and a 30A power relays to power the fan. The control relay is wired to the Hot When Run aux fusebox peezen mentioned. Power was sourced from under the BATT+ box on the left firewall. The controller box fits on the firewall just behind the coil. The control relay makes sure only one of the power relays is enabled at the same time, otherwise the fan will go into Warp 5 and self-destruct. I hooked up the LEDs while I was developing and testing the controller, and left them there because...

    20180413_183835.jpg

    Results:
    It's about 75º in my garage, a lot colder outside, so I didn't think I could give it a good test. I started it up (no leaks!) and it seemed to idle smoother than before. After about a half-hour at idle, with the temp gauge a tick left of the middle indicator (normal) the low seed fan came on, and stayed on for about 15 minutes, then the high-speed fan came on. The temp gauge stayed steady a tick left of the middle indicator the whole time.

    I'll update this post and answer any questions after I've done some road testing.
    Last edited by NevadaMike; 04-14-2018 at 11:29 AM.

  16. #16
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    Awesome write up! I bought that exact fan, the Lincoln MKVIII version, for my Discovery 2 and have been waiting for summer to do that conversion. Such a powerful fan!

    I'm glad I was able to help in some way, nice work!
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  17. #17
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    I just did this mod however im still running hot, maybe living in the Middle East in summer isint helping the situation

    This is the fan i used which is higher CFM (2500) rating than what all the others suggest or have used.
    https://www.summitracing.com/int/par...-398/overview/

    The ignition powered 12V source I used was a fuse in the ABS relay box and which keeps the fan running about 2 seconds after I switch off the car

    My next step is to install the 80/88C fan switch which would help the Aux fan turn on sooner.

    Im thinking of going for a dual electric fan setup and use this to mount the expansion tank

    https://turtlelaboratories.com/colle...ervoir-bracket
    "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."

  18. #18
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    Update - Rev 2

    The last couple of months have been 100º + brutal. In June and July I had to make the 200-mile round trip to Reno every weekday for 40 days of radiation treatments. My son called it a Union job with a long commute - drive for an hour and a half, lie down for 10 minutes, then drive for an hour and a half.T he conversion worked well for a couple of days, then one day after a 75mph stint on the highway I got stopped by a flagman for road construction. The temp gauge rose rapidly, so I pulled off to the shoulder and popped the hood. I hot wired the high speed fan wire directly to the power source wire and made it home.

    I parked the car and didn't get to it until last week for obvious reasons.

    The plastic box I used to house Rev 1 melted. I guess the location I chose on the fender over the exhaust headers was not a good choice. I also decided the 80ºC/88ºC sensor I tapped into to control the two speed fan didn't give me enough latitude on temp/speed selection, and only supplied a signal when the A/C was on.

    Objectives for Rev 2:
    1) Locate the controller and relays someplace cooler in the engine bay
    2) Make the whole system more robust and less susceptible to heat
    3) Provide an emergency override to engage the HS fan continuously
    4) Decouple the cooling fan from the A/C aux fan circuit and provide more flexibility in temperature settings.

    So I sourced two Hayden adjustable thermostats to control the two speeds. I also sourced marine-grade 10GA silicone shrouded copper wire for the power circuits and all-copper connectors to upgrade the wiring. I will be crimping and soldering all connections. The 14 GA/60A Fusable Link was scary to me, so I also sourced two 60A marine grade re-settable circuit breakers. I plan to locate the new controller in the shroud in front of the radiator, probably the coolest part of the engine bay. One of the circuit beakers will feed the two-speed controller. The second is an emergency override which will enable the high-speed fan directly and continuously.

    There is a lot of discussion about too much cooling from an electric fan not allowing the engine to operate at optimum temperature. Duh! When it's 10 degrees outside what temp do you think the coolant in the radiator is? The thermostat does the job of regulating the coolant temp in the engine. One winter day about 20 years ago I couldn't get the temperature gauge past the first tick. A broken (open) thermostat was the problem. I'm not worried abut getting the coolant in the radiator too cold. The cooler, the better.

    The existing A/C Aux fan sensor is located on the output side of the cross-flow radiator, and senses the temp of the coolant going into the engine from the radiator. Some of the literature I've read suggest sensing on the radiator input side (hot coolant from the engine). The range of adjustment on the Hayden sensors is 0ºC to 120ºC. I'm leaning toward putting the sensors on the passenger side (lower, output from radiator) radiator hose directly, rather than poking the mounting strap supplied with the sensors through the radiator fins which potentially (with my luck would definitely) cause a leak and ruin the radiator. The mounting system for the sensor has a foam rubber pad between the clip holding the sensor and the radiator core, so I don't see much of a difference between the foam rubber pad and a rubber hose.

    sensor.jpg

    I'm going to research the logic of sensor location some more today. Any suggestions will be gratefully accepted and considered.

    More to come...

  19. #19
    Join Date
    Feb 2010
    Location
    Hampshire UK
    Posts
    8,867
    My Cars
    99 840ci Sport Indv
    The correct place is the lower hose - this gives immediate feedback of how well the fan/radiator is performing. The auxiliary fan settings of 91/104C for low/high settings are miles out for the control of a main cooling fan - more like 70/85C would be closer to correct - but experimentation would be the plan and better to start with cooler rather than hotter settings!

    The viscous-coupled fan is controlled by neither the upper nor lower hose temperatures - but a combination of the two - it is controlled by the air flowing through the centre of the radiator - but that would be difficult to emulate.

    Why not use the top hose? The top hose temperature exceeds 70C even before the thermostat opens!
    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


    My BMW Repair YouTube Channel
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  20. #20
    Join Date
    Jul 2010
    Location
    Rural Northern Nevada
    Posts
    130
    My Cars
    1991 850i
    Thanks, Timm. Just the info I was looking for.

  21. #21
    Join Date
    Nov 2015
    Location
    Ger
    Posts
    29
    My Cars
    E31 850iA 1992
    I think its not a good idea to remove the visco fan.
    The M70 produce much heat under the bonnet. This heat is verry bad for many parts. For example: cables; seals; coil...
    If you remove die permanet running visco fan, the tempreture is while standing still (traffic light) much more.

    I have an other old car, this was equipted wicht an permmant fan. (no vicso)
    I replaced this fan with a spal. The sensor for the spal is befor the water goes in the radiator. The stock switches are i a position, where the water goes out of the radiator.
    When my car is stopping, after 20s the spal is running. This is good, so the air is still moving - like the factory situation. (permanet or Visco)
    When the car is driving, the spal is fast switched of.

    I think this 16" spal dont reach the air moving that an M70 vico fan does.

    May be its an idea to run the AC fan every time - so there is an air moving under the bonnet without the visco. But its not the same - the visco moves big air volume acros the engine bay.

  22. #22
    Join Date
    Dec 2009
    Location
    MD
    Posts
    1,270
    My Cars
    91 850i
    I had begun this mod a long time ago, even got the fan nicely mounted on custom aluminum brackets but eventually gave up when I couldn't do it the way I wanted with a SPAL computer. Alas, I sold the computer and the SPAL fan I had....now seeing you having done this makes me want to revisit it.

    Kudos on a job well done.
    1991 BMW 850i / V12 5.0L [M70] / ZF4HP24 E/H

  23. #23
    Join Date
    Sep 2008
    Location
    Santa Barbara
    Posts
    3,462
    My Cars
    91 Dinan860 & 91 850 6sp
    Especially in hot climates, there is really no substitute for the engine driven fan as far as efficiency goes.
    That's what the cooling system in our cars was designed for.
    Sure, you can rig up any number of variants of Spal fans, and they will sometimes be enough... maybe.
    But the OEM fan with a GOOD clutch on it will always do the job. If it doesn't, you've got other issues.

    As for fan clutches...
    The OEM BMW clutches are ridiculously pricey ($200+) and don't hold up any better than the Meyle-Behr replacements, although those are under $100 at least.
    Neither of those have proven longevity in my experience though.
    Years ago, I bought a CoolXpert fan clutch from FCP that turned out to be bulletproof. Replaced a few other OEM's to that brand too, all reliable.
    They use a clock spring vs the straight expansion metal, seems to be more reliable from my experience.
    Trouble is, you can't find them today.
    Febi makes one that uses the same approach, and they are also inexpensive. Can't vouch for those, but that is going to be the next one I try when I need one.

    Removing the engine driven fan will not give you any great HP jump, you won't suddenly become King of the Boulevard or even feel it.
    Yes, other cars have stock electric fans - but the whole cooling system was designed for those too.

    Anyway, that's my 8 cents on it...
    Last edited by cartoonz; 08-25-2018 at 10:06 PM.
    '91 Dinan 860 Stage III (new 6L engine)
    '91 Dinan 850 TT stage III (brand new engine) 21st Century Tech meets 18th Century Dinan...
    '91 850i 6sp (mint) (sold)
    '90 Dinan 750iL TT stage III (Guido - The Beast)
    '94 850 CSi The Detroit Auto Show car (restored to factory perfect) (sold)
    '96 850Ci, The George Carlin car
    ''73 3.0 csi, '08 535i, '03 X5 4.6is
    ...and a few other non BMW cars

  24. #24
    Join Date
    Oct 2009
    Location
    St.Petersburg, Russia
    Posts
    30
    My Cars
    KS
    Few tips from me:
    - M73 top coolant crossover pipe (cast aluminum, unites the 2 banks) is supposed to be the same as M70 in size, but it has machined provisions for various temp sensors! So no modifications should be made, you can use that crossover pipe for sensors and plug the un-needed ports.
    - my general fan control idea is similar to OEM, that I've found somehow quite elegant.

    The small OE fan in front of the radiator has a 2-position temp switch sensor (positioned in the radiator):
    - 1st speed - the voltage goes through the resistor which results in a lower voltage on the fan = lower speed.
    - 2nd speed - higher temp of the thermoswitch - the voltage goes without the resistor = high speed.

    We can use M73 coolant crossover pipe, put either 2 or 1 dual position thermoswitch and use a resistor for the 1st speed.
    I suppose that Spal should run with relays, not straight up to thermoswitches.
    Benefits:
    - somewhat bulletproof
    - no PWM high pitch noise (that comes with PWM fan speed control)

    -----

    So what is the biggest Spal that fits?
    16" small fan
    16" medium fan

    I suppose that 16" big fan doesn't fit, being too thick.


    ----
    A bit not sure about the exact thermoswitch ratings, but I wish to keep the engine temperature in between 82-85 degrees C.

    Also regarding water pumps:
    - M70 had an optional 97 mm steel water pump pulley and a shorter belt for Australia spec, i.e. hotter climate. ~100 usd new
    - M73 had an optional 93 mm water pump pulley, but it's made from plastic. They should fit, but I haven't tried.
    11 51 1 704 635 ~35 usd new
    Smaller pulleys should aid heat soak at idle, I hope.
    Last edited by Diskovod; 08-25-2018 at 10:49 PM.

  25. #25
    Join Date
    Apr 2012
    Location
    California
    Posts
    87
    My Cars
    e30M3,F355,BentletGTC,RR
    Peezan, thanks for the write up. So you use existing coolant temperature sensor to trigger the fan. My understand is Spal has an independent temperature sensor that does not need to be connected to coolant temp. sensor. It simply read engine bay temp. at a specific location. Are you aware of this at all? Im contemplation a conversion on my 95 840 and would go that route

    Another question, does anyone know where the coolant temperature sensor is on the 8 cylinder model? I was under hood looking but had a hard time finding it. Thanks.

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