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Thread: *DIY Electric Fan Retrofit

  1. #1
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    *DIY Electric Fan Retrofit

    I'm installing an electric cooling fan, since my mechanical one blew up, I don't want another repeat. I decided to document the event and post it in case anyone else needed some guidance. This is for an M60B30, but the process should be pretty universal.

    Step 1: start by removing your radiator shroud, and mechanical fan/clutch assembly. (note I have much more removed because my mechanical fan decided to break a lot of stuff...) For ease of access, however, you may want to remove your intake pipe and the vacuum hoses on the driver's side.

    Step 2: I used a Hayden Electric 3817 17" fan. Mock fit the fan on the radiator using the brackets shown (sorry I don't have a pic). Start with the top. On the top rail of the radiator, use the holes that are there already. I bored them out a bit to fit a mounting bolt. As for bolts I used stainless steel 10-24 with a phillips head. These thread into wing nuts on the front side of the radiator. Why wing nuts, you ask??? Because the wing catches on the radiator and plastic fan bracket, meaning you don't have to get a wrench in this impossible location, just tighten from front. Now for the fun: get under the car and use a marker or pencil to make marks on the bottom radiator rail. Drill these out. I used a right angle bit on a drill and did it from above. The pipe that runs across the bottom, which I'll affectionately refer to as the b*st*rd bar, blocks access from the bottom. I have small hands, so i can get my hands between the b-bar and the frame, others may not be so lucky...(i can also work under my car w/o jacking it up ) Once everything is lined up, bolt up the fan and tighten down the mounting arms. Take your fan shroud and make marks on the top where the fan mounts are. Take the fan out.

    Step 3: Now cut the shroud to fit the fan brackets. This is a bit of trial and error (read: A LOT of trial and error) I used a dremel with a sculpting tool, there are probably better options though. When finished, it should look something like this.

    Step 4: Saw off the lips on the bottom brackets of the fan. This will allow you to slide the fan and shroud down into the radiator.

    Step 5: Mount your thermostat probe. I used a Hayden 3647 adjustable thermostat. Use something like a pencil (I used an allen wrench because it was the closest thing in arm's reach) to spread the radiator fins. Insert your probe. I had the probe run beneath the AC piping for a clean install, but feel free to be lazy and run it over them.

    Step 6: Slide the fan and shroud down into the radiator. If all goes well, your holes should line up and you can bolt the fan to the radiator. Secure the shroud with the clips.

    Part 1 of the install is done.

    Part 2: The Wiring. Coming Soon.
    -Nick

  2. #2
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    very nice. I really want to do this. Can you get us links to where you purchased everything, and prices if you don't mind? Thanks

    excellent write up so far
    "Health is merely the slowest form of death."

  3. #3
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    Careful with the wiring there bro - electric fans draw 20 - 40 amps. That would suck to short out and burn the car down

  4. #4
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    I got the electric fan from a website called acpartsguy. The shipping was fast, albeit not as cheap as I'd like. Summit Racing also has the fan, for about $5 cheaper I believe after shipping costs.
    http://www.acpartsguys.com/cooling_fans__blades

    The adjustable thermostat I got from Amazon.
    [ame]http://www.amazon.com/gp/product/B000C3BB6M/ref=s9_sims_gw_s1_p263_t1?pf_rd_m=ATVPDKIKX0DER&pf _rd_s=center-2&pf_rd_r=102WC7MGX1CBEF9K1H6P&pf_rd_t=101&pf_rd_p =470938631&pf_rd_i=507846[/ame]

    If you need a new fan shroud as well, I got mine from Partstrain. Just enter in your car to get the right one.

    Glad you like the writeup. I'll post the wiring portion tomorrow after I finish it all up and take pics.
    -Nick

  5. #5
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    is that all you'll need? I am assuming you are grounding the unit on the body, and taping into a 12v power source and thats it? The relays and stuff are built in with the thermo right?
    "Health is merely the slowest form of death."

  6. #6
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    Indeed. I'll delve into details tomorrow with pics to boot. But suffice to say that Hayden thermostat/relay is really nice. Wiring is included, and it's all one piece. The wiring is heavy enough for the load, i forget the AWG off-hand. The relay is good for 40A, but it's fused for 25A. The fan has a draw of 23A on high speed, and normal draw on the low setting is like 17A i think. The specs are available on the sales websites, or you can go to www.haydenauto.com and d/l the catalog.
    -Nick

  7. #7
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    Quote Originally Posted by carmaniac13 View Post
    Indeed. I'll delve into details tomorrow with pics to boot. But suffice to say that Hayden thermostat/relay is really nice. Wiring is included, and it's all one piece. The wiring is heavy enough for the load, i forget the AWG off-hand. The relay is good for 40A, but it's fused for 25A. The fan has a draw of 23A on high speed, and normal draw on the low setting is like 17A i think. The specs are available on the sales websites, or you can go to www.haydenauto.com and d/l the catalog.

    Yeah you'd think that, I've seen electric fans melt down relays and fuse boxes. Not pretty stuff.

    Go ahead and bite. Plenty for everyone.

  8. #8
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    any updates?
    "Health is merely the slowest form of death."

  9. #9
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    Sorry for the delay on the electric side of the install. This part is fairly straightforward. I usually don't, but you can disconnect your negative battery terminal if you're uncomfortable working with electricity.

    Step 1: Install inline fuses on the main power line and secondary power line on the fan controller. This gives me three fuses in total: a 30A for the main power line to protect everything (install this one as close as possible to the beginning), a 25A that comes preinstalled on the low speed wire, and a 20A (per fan's recommendations) on the high speed. This keeps the fan from drawing more than 30A in total, or more than 25A or 20A per channel individually.


    Step 2: Attach ring terminal to the Positive power lead, and connect to the distribution block.


    Step 3: Decide how you want to connect your fan. I used quick disconnect connectors, but you could solder the wires as well. Make a ground loom for the fan and controller (or ground them separately) I had speaker wire laying around, so both strands of 12ga should be quite sufficient for the fan ground. I wrapped those ends with the ground from the controller and attached them to a ring terminal.


    Step 4: Attach the ring terminal to the grounding bold on the right fender, just under the hood lip. Because of the ring terminal I used (American size i suppose) I had to bore it out ever so slightly to fit on the grounding bolt.


    Step 5: (Optional) Attach the green AC turn-on wire to the magnetic switch wire on the AC compressor. I didn't use this because that's what the auxiliary fan is for, but it's a nice feature if you decide you need it. (no pics)

    Step 6: Fish the ignition wire into the engine control box. This is where you will tap an ignition wire. (It's the yellow wire on the top, use a snake or pull wire to pull through the gasket.)


    Step 7: Splice the ignition wire into an ignition wire on the car. You don't need to use the wire I used, check with a Bentley or wiring diagram to determine which wire comes on with the ignition. The yellow wire will draw next to no current, so don't worry about shorting or overdrawing current on a wire.

    I used the Red w/ Blue stripe wire on the plug farthest to the passenger side. Once again, this part is probably the most vehicle specific, so consult a manual or get a voltmeter and check for power during ignition.
    Alternately, if you mount your controller on the other side of the engine bay, you could tap into one of the fuseboxes on that side (ABS, etc). Also, if you don't mind the fan being on after the engine shuts off, you can just connect the yellow wire with your main power wire.

    Check all your connections and you're done. Start your engine and make sure the fan turns on once the engine reaches operating temperature (or just starts to exceed it) Enjoy your new electric fan.
    Last edited by carmaniac13; 04-22-2009 at 08:09 PM.
    -Nick

  10. #10
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    gawd I want to do this, but I cant even pay my overdraft fees

    Great write up dude. How loud is this fan, and how often does it go on and off?
    "Health is merely the slowest form of death."

  11. #11
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    The fan is a lot quieter than the mechanical one.

    Unfortunately, my thermostat probe isn't working, so Hayden is sending me a new one. That was part of my delayed response. I'm hoping it will come within the next few days, then I'll give an update once i start putting it all into use.
    -Nick

  12. #12
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    I like you setup. Have you considered using a DC Control fan controller? I use one on my rock crawler jeep with a Lincoln Mark8 fan and it has no problem keeping my 5.8l cool. The controller can handle a lot of amperage, and it's a pulse width design so that it slowly ramps up the fan. It also has it's temp sensor located on the output side of the radiator. It really works well. No longer do I have to babysit the temp gauge.

    www.dccontrol.com
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  13. #13
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    Ah PWM, nice. I'm probly gonna splice in some extra wire on the probe so I can play around with location. Once I get the probe in working order I should be able to tailor the setup quite nicely, as the controller is adjustable for starting temperature and kicks on the second fan, (in my case the high speed) if the primary fan (low speed) isn't doing the trick.
    -Nick

  14. #14
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    how does this setup work? I am really into doing this..
    "Health is merely the slowest form of death."

  15. #15
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    ummm, bump!
    "Health is merely the slowest form of death."

  16. #16
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    It works pretty well. The engine stays a very small tick above the center line. I've also ran the system through its paces by idling in 90F weather AC and soundsystem (big amp in the trunk) blasting trying to put a big load on the engine. The temp went another small bit above the center, but it stayed there and the auxiliary fan wasn't kicking on when I turned the AC off, so it was staying below 196F ish or whatever that aux fan turn on is.

    Also to note, that hayden 3647 is unfortunately not a 2 speed fan controller. Both leads turn on simultaneously. Hayden does make a 2 speed fan controller, but it's rather expensive imo. Sorry for the misinformation.
    -Nick

  17. #17
    eaglecomm's Avatar
    eaglecomm is offline Senile Member BMW CCA Member
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    A quick note.. when I installed an electric fan in my E38, I had read to make sure the probe was on the incoming side of the radiator. That way it was judging the actual coolant temperature of the engine and responding as necessary. If you have the temp probe next to the output of the radiator, and if the radiator is doing its job, then it will have cooled off the coolant somewhat and your fan may not be coming on as often as it should to keep your engine cool. Just my 2cents! :-)

  18. #18
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    -deleted- I wuz rong.
    Last edited by attack eagle; 07-27-2009 at 12:11 AM.

  19. #19
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    eaglecomm is offline Senile Member BMW CCA Member
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    NO, the fan needs to kick on when the ENGINE gets to a certain heated temperature. NOT when the radiator cooled temperature is lower. Then it may never get hot enough to kick on the fan if the fan is set properly.

    Here are some links to confirm it.
    This one from an electric fan maker 'flex-a-lite' stating 'Insert the temp. sensor as close to the inlet hose as possible' which would be the hose on the driver's side coming in to the radiator.
    http://www.flex-a-lite.com/auto/50-55-FAL-99965.pdf

    Another link also states the 'inlet' side.
    'The thermostat will typically have a probe that is to be positioned on the radiator somewhere. I like to put mine into the fins in the corner where the upper rad hose connects. This is the hottest area of the radiator, and a generally convenient spot. It should go without saying that the thermostat be located away from moisture, dirt and excessive heat.
    http://www.aaroncake.net/rx-7/efaninstall.htm

  20. #20
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    nice, well done. Comment retracted.

  21. #21
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    eaglecomm is offline Senile Member BMW CCA Member
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    No worries, I doubted myself for a second too.

  22. #22
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    How would one go about wiring the fan to a switch in the cabin.

    I do not want to have it go by the temp probe. I want to have it wired to a switch so I can turn it on manually. My brother had one like that in his a4, and it was nice to just be able to flip it on whenever we got stuck in traffic or something of the sort...to avoid any sort of overheating (probe failing,etc)
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  23. #23
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    Wiring it without a temp probe is even simpler. Just get a relay rated to handle your fan, wire the engine power from your controller or wherever you want to grab it, then wire it to the relay turn-on, then run the ground of the turn-on from the relay to your kill switch and ground the other wire from your kill switch.
    This way the fan can only turn on if the engine is running, and the kill switch is engaged.
    -Nick

  24. #24
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    eaglecomm is offline Senile Member BMW CCA Member
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    Adding to what Nick said.. I would consider running the switch as a kill switch in addition to running a temp sensor probe. You can still kill the fan this way, but you would also have the choice to let the probe run the fan other times. With a switch that you have to turn on all the time just to get the fan to turn on, you will inevitably forget at the most inopportune time and could do damage to your engine. It 'could' happen someone comes to borrow it and forgets or doesn't know to turn on the switch and lets it idle on a hot day with no fan running for awhile. It 'may' have happened to a friend of a friend's ex-brother in-law I once knew. Its always the issues you don't think will happen that cause the forehead to palm. Just a precaution. :-)
    Last edited by eaglecomm; 08-21-2009 at 10:36 AM.
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  25. #25
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    Just a thought...what about wiring it into the foglight harness. That way when the fogs are on, the fan is on.
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