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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E36 (1991 - 1999)

E36 (1991 - 1999)
The E36 chassis 3-Series BMW was a huge hit among driving enthusiasts from the first moment the car hit the pavement. The E36 won numerous awards over the years it was produced and is still a favorite of many BMW enthusiasts to this day! -- View the E36 Wiki

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  #1  
Old 05-18-2011, 07:55 PM
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drive by72 drive by72 is offline
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Doing the FDM? Installing an aux fan? Read this

Recently theres been about 5000 threads regarding auxiliary fans and how to wire them. So, being one who has done the FDM and wired an aux fan into my E36, I figure its time to make a central thread for everyone to go to.

First things first,

What is FDM, and why should I bother?
FDM is short for Fan Delete Mod. This is a popular and widely debated modification where you take the mechanical fan driven by a temperature clutch bolted on the water pump. As the ambient temperature around the engine increases, it causes the clutch to tighten and increase the speed of the mechanical fan. This in itself is a great system, however it is let down by the fact that BMW fans like to act like grenades, which is a date with disaster for your radiator. Eventually the fan becomes very brittle and a fan blade with break off, causing the fan to loose its balance and a chain reaction of blades breaking off will occur. The shards will take everything out in their path, and since the fan is an inch away from the radiator, that is the first thing to get taken out.

Ok, so now I know what could happen to my radiator. What can I do?!
You have two options. Replace the fan every 75K miles, or put an electric fan in. While the fan and clutch only cost around 50 bucks to replace, some just dont want it in there period.

So your saying you can eliminate the plastic fan without overheating your engine? How?!
Simply put, you put an electric fan in and take the mechanical fan out. Its a tad more complicated than that though, but its easy enough for a DIY'er to do. You can do it for less than 200 bucks, thats with a good Spal fan. If your like me and a cheapo, you could use the electric fan that came with your eBay radiator, but thats a different story and I wouldnt recommend buying an ebay fan for this purpose.

Alright, I decided to do the FDM. What do I need?
You will need the following:
-electric fan
-appropriate fan shroud
-mounts for the fan to the radiator
-roughly 10-15 feet of wire, power wire should be around 10-12 gauge
-fuse holder and fuse
-relay
(optional)- prewired relay hookup
-shrink wrap
-electrical tape
-terminals for ground
Patience, swear words, and extra sweat is recommended as well. It will help when you run into a snag.
-Some use lower temp T-stats and water-wetter, but Im using neither and I'm getting along fine

Alright, I have all the parts. Now what?
Now comes the fun part, installing all your shiny new parts Start by taking the radiator out, fan shroud off, and take the mechanical fan off. Also, dig the connector and wires for your OEM aux fan out of its shroud and follow the bundle up to where it splits on the harness. Mark this, you will need it later. Dry fit the fan to the radiator, being careful not to damage the fins while you do this. If you plan on replacing the radiator soon, wait to do this until then, because the mounting brackets you'll need to make will be a little different for every radiator.



The radiator I used had little tabs for the OEM shroud, I just took some sheetmetal and cut some notches to fit in these tabs. I used flat nuts and flatheaded screws with the head towards the radiator to mount onto the brackets, and the brackets are friction fit/gravity fit. They arent moving, since the fan shroud presses against them and the tabs are U shaped to fit snuggly around the tabs on the radiator. Make sure you leave room for the lower radiator hose to the expansion tank. Use the fan shroud you are going to use to dryfit the fan. This is important for proper fitment.



Once your fan is properly fit, Shimmy the radiator hose in the fan shroud and fit the shroud over the radiator. Once that is all connected, install the radiator again. You should have 2" or so between the fan and the water pump. Make sure you have access to the wires to the fan, you'll need to get to them.



Now heres the magic wiring diagram that is so often asked for:


This is where you need to do your wiring. Run a fused power wire over to the positive jumper block by the DME. It needs to be a decent gauge as the fan will probably be drawing alot of juice and it is a bit of length to run.



I put my relay over by the drivers strut tower. Zip tied it to the wire bundle that was there already. The blue signal wire in the diagram comes from that bundle you pulled from the OEM aux fan earlier (see pic below). You can tap that wire whichever way you want, wire nut, crimping, etc. Whichever way you choose though, make sure you shrink it or tape it up with good electrical tape, and if you tape do 2 or 3 layers. Its that important. If this wire corrodes, neither one of your fans will work and you will overheat in the right conditions. I did a wire nut and did 4 layers of electrical tape then another one over that.

Wire bundle from aux fan (under car)


Relay location


Hang in there, youre almost done. Once you have your relay wired up, hook up your fan. Pretty simple here, one from the relay and the other ground. I found a neat little M6 stud on the body that makes a great ground, for the fan and relay.



Once you have this hooked up, its time to test. You can do this a few ways. One is jump the coolant temp sensor on the radiator, jumping terminal 1 and 3. Another way is get power to the signal side of the relay. You can grab a jumper and hook it up to the positive block, and then touch the side of the relay that the blue wire is hooked up to. This should signal the fans to turn on. Make sure you have a fuse in when you do this, 30 amps should be plenty. If you need to, hook an alligator clip up to a screwdriver and use the screwdriver as a poker to the relay. Make sure to touch the right terminal, otherwise you'll blow that fuse to smithereens . If everything checks out, then congratulations, you are done. Take her for a drive and try to get the fan to kick on. The best way is drive till operating temp, then bring it back to your workspace and let it idle. Idling is the best way to reduce coolant flow in the radiator while keeping heat in the engine, which is what you want when your looking to see if this works. You can also turn the AC on, as that will cause the OEM fan to kick on by default and because of the wiring, your fan should switch on too. If it doesnt work, make sure you have good grounds, your connections are good, and the relay is clicking. Also make sure you wire the relay correctly, the sideways terminal should be ground. The middle terminal doesnt need to be used as ground either.


And that my fellow E36'ers, is how you do the FDM and install an aux fan. Post any questions here, and I'll do my best to help you out
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  #2  
Old 05-19-2011, 11:58 AM
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Nice, dude. Looks very helpful!
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  #3  
Old 06-13-2011, 06:26 AM
kuleinc kuleinc is offline
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Any idea where to get a lower degree fan switch?
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  #4  
Old 06-13-2011, 10:35 AM
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Pelican will have one I believe

Note- I didnt run a lower degree t-stat or switch and I'm getting along just fine
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1997 328iS... HR coilovers, Brembo F40 calipers, camber plates, it needs a CUMMINS!!

1990-somethin Chevy K3500... Cummins, cab swap, 5 speed, and lots of motor work. 20 MPG, 40 PSI, 507 ft/lbs torque
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Old 09-10-2011, 05:22 PM
lkoch57 lkoch57 is offline
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I spoke to you before, I'm not getting power to the OEM blue wire or the blue/black wire which follows the wiring harness up to the fuse box, replaced the low and high speed relays, have power on # 85 prong for low speed relay with replay pulled and on #86 prong high speed relay with relay pulled, but no power at the other end. checked the switch on side of radiator and it has tested okay.
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Old 02-05-2012, 04:04 AM
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Did you use the oem shroud?
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Old 02-17-2012, 07:12 AM
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I'm currently running the wire right now. I feel pretty dumb because I can't figure out where the "ground - middle terminal" wire goes. Can anyone fill me in?
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  #8  
Old 02-17-2012, 09:52 AM
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If you mean the middle terminal on the relay shown in the wiring diagram, you can disregard that ground. It will not make any difference in operation.
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1997 328iS... HR coilovers, Brembo F40 calipers, camber plates, it needs a CUMMINS!!

1990-somethin Chevy K3500... Cummins, cab swap, 5 speed, and lots of motor work. 20 MPG, 40 PSI, 507 ft/lbs torque
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Old 02-17-2012, 10:05 AM
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While this thread is bumped...

I bought a mishimoto fan recently since my aux fan went out (no engine fan).

The problem is that my first aux fan died after 2-3 months of good use. I have a jumper at the aux fan thermostat so that the fan runs at low speed all the time. So I replaced the fan with one from my parts car. That fan worked perfect, but then died after less than a month....

Any idea why this could be happening? I don't want my expensive mishimoto fan to get fried as well.
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Old 02-17-2012, 10:15 AM
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Un-jumper your coolant temp sensor. Running the fan all the time is likely the cause of the fans dying. You should never need it running all the time. And once you have your mishimoto installed, the OEM/aftermarket fan will hardly ever run for longer than a few minutes.
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RIP Ben "Jever" Doebele, we wont forget you

Please, call me Chadley

1997 328iS... HR coilovers, Brembo F40 calipers, camber plates, it needs a CUMMINS!!

1990-somethin Chevy K3500... Cummins, cab swap, 5 speed, and lots of motor work. 20 MPG, 40 PSI, 507 ft/lbs torque
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Old 02-17-2012, 10:31 AM
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Quote:
Originally Posted by drive by72 View Post
Un-jumper your coolant temp sensor. Running the fan all the time is likely the cause of the fans dying. You should never need it running all the time. And once you have your mishimoto installed, the OEM/aftermarket fan will hardly ever run for longer than a few minutes.
A few months of running all the time will not make a difference. The fans would have died soon regardless of whether they were being used all the time for a few months, or as they were intended. Besides, a lot of people's fans are turned on nearly all the time anyway, since many people have their A/C on all the time.

I say it was circumstantial. My only concern about the mishimoto fans is that I have no idea how well they are sealed against the elements. Since they're so cheap, I'd guess probably not very well.
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Old 02-17-2012, 10:44 AM
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Hmm..... Could be random I suppose. And the mishimoto fans are certainly not inexpensive...

http://www.mishimoto.com/bmw-e36-per...ud-kit-92.html

I only paid $100 shipped for that set brand new, so I got a hell of a deal. But I still have another good aux fan that I could've used. And the mishimoto fans sit inside the engine bay, so they won't be experiencing very much of the elements.
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Old 02-17-2012, 12:20 PM
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Quote:
Originally Posted by cj.surr View Post
Hmm..... Could be random I suppose. And the mishimoto fans are certainly not inexpensive...

http://www.mishimoto.com/bmw-e36-per...ud-kit-92.html

I only paid $100 shipped for that set brand new, so I got a hell of a deal. But I still have another good aux fan that I could've used. And the mishimoto fans sit inside the engine bay, so they won't be experiencing very much of the elements.
No, they're pretty cheap. You can get the same Mishimoto setup for $185 shipped. ECS Tuning used to carry it for like $167 or something in that ballpark.

http://www.ebay.com/itm/Mishimoto-Al...dcf459&vxp=mtr
PS: their photo has got to be wrong, since that shroud will not fit on a 6-cylinder radiator. The ones below are the correct style.

Or you can get a number of other setups, which are probably the same quality for under $100 shipped:

http://www.ebay.com/itm/1992-1998-BM...d094e0&vxp=mtr

http://www.ebay.com/itm/BMW-E36-92-9...a371b7&vxp=mtr

I'm not knocking Mishimoto, because I've never used their products, but it is just Chinese made stuff. Can't be as good as Spal.
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Last edited by ZeGerman; 02-17-2012 at 12:23 PM.
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Old 02-17-2012, 12:36 PM
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Eh, I've only heard good things about Mishimoto.


I don't really trust the thermostat though, because it'll be the only fan... Maybe I could wire it to run at the low setting all the time, and high setting at the normal time? I don't have A/C, so maybe the high setting isn't even necessary.
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Old 02-17-2012, 12:39 PM
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If it were my car, I'd figure out what the operating range is and then run an appropriate sending unit.
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Old 02-17-2012, 12:54 PM
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What do you mean by an appropriate sending unit? An OEM one?
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Old 02-20-2012, 08:37 PM
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Many Thanks

Quote:
Originally Posted by drive by72 View Post
If you mean the middle terminal on the relay shown in the wiring diagram, you can disregard that ground. It will not make any difference in operation.
I just finished the cooling system overhaul. I could never have done it without all the information on this and other forums. It took some creativity to get the tank to attach to the new shroud, but it worked out in the end.

Note: my fan did NOT work unless the middle terminal/ignition wire is grounded.

And now the proof is in the pudding... er.. pictures.


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Old 02-20-2012, 08:44 PM
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Lookin good!

I didnt need to wire in the middle terminal on the relay, but then again I'm using a relay out of a Ford Econoline for my relay (not that it matters, relays all work the same)
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1997 328iS... HR coilovers, Brembo F40 calipers, camber plates, it needs a CUMMINS!!

1990-somethin Chevy K3500... Cummins, cab swap, 5 speed, and lots of motor work. 20 MPG, 40 PSI, 507 ft/lbs torque
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Old 02-20-2012, 09:10 PM
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I just installed that Mishimoto fan and shroud an hour ago. However, the fan is touching the waterpump, might be because I'm using an OEM rad. I'm desperate because I have like 100mi of driving to do tomorrow morning. I'll post a picture in a minute.
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Old 02-20-2012, 09:16 PM
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Pictures



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Old 02-20-2012, 09:18 PM
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drive by72 drive by72 is offline
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OEM radiator on a Mishi fan/shroud? I'd imagine the Mishi radiator wouldnt be that much thinner than an OEM rad. And even so, I have a good half inch or so between my fan and water pump.

Edit...

Looks like your radiator doesnt have the little plastic top thingers that hold it close to the support...

Also, how is the fan mounted to the shroud? Similar to mine or...?
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RIP Ben "Jever" Doebele, we wont forget you

Please, call me Chadley

1997 328iS... HR coilovers, Brembo F40 calipers, camber plates, it needs a CUMMINS!!

1990-somethin Chevy K3500... Cummins, cab swap, 5 speed, and lots of motor work. 20 MPG, 40 PSI, 507 ft/lbs torque

Last edited by drive by72; 02-20-2012 at 09:20 PM.
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Old 02-20-2012, 09:23 PM
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cj.surr cj.surr is offline
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The plastic radiator clips were loose, but even if I pull the radiator against the support, there's only like 1cm of clearance.

The fan is just bolted onto the shroud. Maybe I could move it lower on the shroud... It would still be close, though.
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Old 02-20-2012, 09:28 PM
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1cm is close, but should be fine as long as it doesnt move.

I ask because maybe you could shave a cm or two by using flat nuts and a screw like I did, and bring the fan closer to the radiator itself
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RIP Ben "Jever" Doebele, we wont forget you

Please, call me Chadley

1997 328iS... HR coilovers, Brembo F40 calipers, camber plates, it needs a CUMMINS!!

1990-somethin Chevy K3500... Cummins, cab swap, 5 speed, and lots of motor work. 20 MPG, 40 PSI, 507 ft/lbs torque
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Old 02-20-2012, 09:45 PM
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1cm is with everything pushed forward as far as possible. I think I'm gonna forget about the fan tonight and just show it to my mechanic tomorrow, since he's on the way where I have to go. I think he had a Mishimoto rad in the back room...
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Old 02-20-2012, 10:05 PM
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I have a cm of clearance if I'm lucky. The waterpump is close but not touching the fan. I snugged the shroud and radiator as tight as I could to the front of the engine bay. If i had the means I would fabricate a delrin, or similar plastic, disk to protect the fan wires.

If you use the mishimoto rad you can file the aluminum brackets so the shroud sits lower and tighter.
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