My Fan Delete

[wagnerism]

**Edited now that I have done most of the work**

I did my research and found many conflicting opinions regarding whether it should be done and how it should be done. This is how I ended up doing my own viscous fan delete based on the potential risks.

Reasons - one or all of which may be true - There's some debate so choose what you like!
- The old fan dries out and shreds to pieces, damaging the radiator and hood.
- Viscous clutch siezes up and shreds to pieces at high RPM, damaging the radiator and hood.
- Worn engine mounts cause the fan to bust up stuff
- The fan robs power from the engine and/or slows acceleration
- It is 2018, why are we still dealing with viscous fans? (I made that one up)
- The viscous fan makes more noise

I believe I did a rather clean job of it and am sharing it here in case it helps anybody. I could only add five pictures so I picked the most helpful ones.

The significant risks were overheating and burning out the OEM auxiliary fan. To mitigate these risks I left the auxiliary fan alone and installed an electric fan that will operate temperatures lower than what triggers the auxiliary fan.

⦁ The stock thermoswitch and auxiliary puller fan were left in place. The thermoswitch operates at the stock 91/99c temperatures.
⦁ Thermostat

⦁ Replaced with one that opens at 80c ($12, includes round seal)
⦁ A new seal is needed ($1) but I replaced the corroded housing ($12, seal included) - if you still have the plastic one, replace it!

⦁ Fan Replacement

⦁ The viscous fan was replaced with a Spal puller fan ($95) edit, link added.
Spal 30101516 16" Straight Blade Low Profile Fan
(note: Spal does not provide a pigtail connector for whatever they put on their fan!)
fandelete-spalfan.jpg
⦁ The puller fan was mounted using those thru-radiator zip ties ($8)
The low profile fan fits in the space vacated by the viscous fan. The OEM shroud remained. I found that you can't remove the OEM shroud once the fan is mounted because the gap between the new fan and the water pump is too small.

⦁ Second Thermoswitch

⦁ Since the original thermoswitch was left in place, a 36mm (not 40mm) water temp sensor adapter was installed inline on the lower radiator hose ($6)
edit: I measured the radiator ports for the adapter size, only to find that the lower hose is skinnier in the middle. I bought a 36mm version found on Amazon for $4 less.
edit: To make the thermoswitch fit I first drilled out the existing threaded sensor hole with a 1/2" bit, then cut threads using a M14x1.5mm tap.
fandelete-tempsensoradaptor.jpg
⦁ Thermoswitch, 80/88c was added ($19) using a metal seal ring washer ($0.26)
fandelete-thermoswitch.jpg
⦁ None of the water temp sensor adapters had the right threads. The 36mm water temp sensor adapter was drilled out with a 1/2" drill bit and threads cut with a M14x1.5mm tap. (Tap was $9, drill press and 1/2" drill bit was on hand)

⦁ Electrical

⦁ Resistor for low-speed operation - 0.5ohm/100W ($8)
fandelete-resistor.jpg
⦁ Two SPST relays with integral fuse, one each for low speed and high speed ($16 for six)
fandelete-relays.jpg
⦁ SPDT on/off/on switch ($5)
⦁ Add-a-fuse adaptor and 14GA wiring (on hand)

How it is wired:
Relays are wired in a "ground trigger" configuration to simplify wiring. Starting from the driver-side fuse box under the hood:
⦁ +12VDC Source: Add-a-fuse with 50A fuse
@Blacklane says to run it from the positive battery terminal located near the DME's case. Much easier!
⦁ Run wire to the area where the DME and relays are located.
⦁ Connect +12VDC Source to four relay terminals

⦁ Relay-L pin 85 (White) coil
⦁ Relay-L pin 30 (Red) contact
⦁ Relay-H pin 85 (White) coil
⦁ Relay-H pin 30 (Red) contact

⦁ Connect Fan Power

⦁ Relay-L pin 87 (Blue) contact connects to 0.5ohm/100W resistor
⦁ 0.5ohm/100W resistor connects to Relay-H pin 87(Blue) contact
⦁ Relay-H pin 87 (Blue) contact connects to puller fan positive (+)
⦁ Puller fan negative (-) connects to chassis ground

⦁ Connect thermoswitch trigger - There are three pins and the connector has notched, curved, and flat sides

⦁ "common" - between the notched and curved sides is wired to ground
⦁ "low" - between the curved and flat sides is wired to Relay-L pin 86 (black) coil
⦁ "high" - between the notched and flat sides is wired to Relay-H pin 86 (black) coil

⦁ Connect manual trigger - SPDT on/off/on switch in the driver's area
There is a path through the firewall behind the glove box according to my internet searches. I haven't run that part yet.

⦁ Switch common is wired to ground
⦁ Switch "I" is wired to Relay-L pin 86 (black)
⦁ Switch "II" is wired to Relay-H pin 86 (black)

Operation
⦁ Below 80c neither pin on the thermoswitch is connected to ground
⦁ Above 80c the thermoswitch "low" pin connects to ground, energizing Relay-L which powers Relay-L pin 87 that is connected to the 0.5ohm/100W resistor and the puller fan. This is also activated by manual switch "I"
⦁ Above 88c the thermoswitch "low" pin remains connected to ground and the thermoswitch "high" pin connects to ground, energizing Relay-H which powers Relay-H pin 87 that is connected to the puller fan. This is also activated by manual switch "II"

[Mr Bingley]

That seems thorough and well thought out. By keeping the aux fan you are hedging your bets, but since you don't have a shroud, it's a good hedge. I like this approach a lot better than simply yanking the viscous fan and closing the hood. There should be a kit for doing just this.

[Blacklane]

I love what you have done. I did something similar, but less elaborate. However, I drew power from the battery connector on the other side of the engine bay. There are several power lugs under that connector and plenty of room for an in-line fuse holder and several relays in that box.

[saneesh8]

Interesting and well done..

What would be the real advantage in doing this? Other than the safety issue when the mechanical fan crashes into the radiator when the water pump have issues? Did you see any difference? I believe it will be silent?

[BimmerBreaker]

Good job and looks like a lot of hard work went into it

More of an "electric fan conversion" than a "fan delete" ...since you still have 2 fans at the end of the day... but thats splitting hairs

[wagnerism]

Interesting and well done..

What would be the real advantage in doing this? Other than the safety issue when the mechanical fan crashes into the radiator when the water pump have issues? Did you see any difference? I believe it will be silent?

I'm repeating what I read elsewhere, so I'm open to being corrected here.

The primary advantage was removing viscous fan's drag on the engine, relevant mostly when accelerating.

For the safety issue, I believe the viscous fan crashes the radiator when the motor mounts go bad.

For noise, I'm unsure if the viscous fan was engaging at high temperatures. I know it wasn't engaging at startup.

[Blacklane]

The engine-driven fan often explodes and leaves big outward dents in the hood. I think it's part of the "Ultimate Driving Experience."

[rf900rkw]

The mechanical fan gets old, dry, and eventually explodes; taking out the radiator, hoses, hood, belly pan, etc. This has nothing to do with engine mounts. That was a red herring introduced many years ago and disproved logically many times, yet it will not die. It also does not require a water pump failure. A siezed viscous will do it, or just age.

⦁ The puller fan was mounted using those thru-radiator zip ties ($8)

This one thing unfortunately renders the fan to nearly useless. Without a proper duct/shroud the fan can not do it's job.

[wagnerism]

The mechanical fan gets old, dry, and eventually explodes; taking out the radiator, hoses, hood, belly pan, etc. This has nothing to do with engine mounts. That was a red herring introduced many years ago and disproved logically many times, yet it will not die. It also does not require a water pump failure. A siezed viscous will do it, or just age.



This one thing unfortunately renders the fan to nearly useless. Without a proper duct/shroud the fan can not do it's job.

What about doing that while retaining the OEM shroud?

http://www.realoem.com/bmw/enUS/show...93#17111723031

[Mr Bingley]

The water pump shaft pokes into the space where the electric fan would mount in the OE shroud. Zionsville makes an offset mount replacement aluminum shroud and fan, but as with all things Zionsville, it's expensive:

http://www.zionsvilleautosport.com/s...xpansion-tank/

[Mr Bingley]

Oh, and I don't think that bad motor mounts leading to the fan contacting the radiator and exploding is a bugaboo--at least on an S52 with an S54 radiator mounted in it, as that is what appeared to happen to me with a new OE fan, fan clutch (and S54 radiator), but bad mounts--now I wasn't under the hood watching it happen, but that is certainly what appeared to happen based upon the circular cut in the cooling fins. Understand I was stressing the entire system under shift-at-redline maximum supercharged acceleration when something happened--either the boost pressure bypass valve opened or the fuel pump sucked air momentarily--but there was a great and sudden let off of power, the drive train lurched forward, and the fan pushed into the radiator leaving a clean circular cut. Later examination revealed that both mounts were bad.

[deni2s]

The water pump shaft pokes into the space where the electric fan would mount in the OE shroud. Zionsville makes an offset mount replacement aluminum shroud and fan, but as with all things Zionsville, it's expensive:

http://www.zionsvilleautosport.com/s...xpansion-tank/

No issues with OE shroud if you choose narrow spal puller (if I remember correctly it was like 51mm). Probably medium might work too.

- - - Updated - - -

There should be a kit for doing just this.

You can buy all required parts (except for temp sensor adaptor) from Spal. I posted all required part numbers in some other thread.

[wagnerism]

The Spal fan I used left about 1" clearance between the water pump fan mount and the back of the fan.
https://www.amazon.com/Spal-30101516.../dp/B003PB46JM

[wagnerism]

Updated OP with what I learned in this thread and during installation. Thanks!

[Jakechan]

I'll bump this thread instead of making a new one. Great write up by the way.
I notice here the fan thermo switch is installed in the lower hose, in other threads I've seen it placed in the top hose.
I have an 85 degree C switch set up ready to go on my M54, up or down?

Thanks

[BladeRunner919]

Personally I'd say bottom, because that is where you measure the temperature of the coolant exiting the rad and going back into the engine, and that 'output temperature' is what the fan is aiming to keep within range. That said there's not really much difference as long as your choice of switch reflects whether it is placed before the rad or after it.

[Tigershark48]

The power robbed from the engine to spin the viscous fan has to be fractional. The power utilized would be for pulling x amount of air with the fan blades. The electric replacement fan would have to do the same indirectly requiring close to the same amount of power produced by the engine. The only negligable gain in power would happen with a viscous fan delete only without a replacement. But again, that power gain would be a tiny percentage of the total horsepower produced.

There was also mention of the viscous fan noise noting that it did not engage at startup. Mine definitely did and it produced a lot of blowing air noise with the hood open. I did a viscous fan delete only and all I hear now with the hood open is the engine.

I pulled my fan at the end of the season. This summer I’ll be monitoring my temp for any possible overheating, but expect none. The hottest days in Wisconsin see temps in the 90s. Unlike Arizona with upwards to 30 degrees hotter. My driving will also be pleasure cruising on rural highways with no commutes in slow speed traffic.

[ihm96]

Yeah any power increase felt is purely placebo, but the added engine noise and less worry of damage makes it worth it

The power robbed from the engine to spin the viscous fan has to be fractional. The power utilized would be for pulling x amount of air with the fan blades. The electric replacement fan would have to do the same indirectly requiring close to the same amount of power produced by the engine. The only negligable gain in power would happen with a viscous fan delete only without a replacement. But again, that power gain would be a tiny percentage of the total horsepower produced.

There was also mention of the viscous fan noise noting that it did not engage at startup. Mine definitely did and it produced a lot of blowing air noise with the hood open. I did a viscous fan delete only and all I hear now with the hood open is the engine.

I pulled my fan at the end of the season. This summer I’ll be monitoring my temp for any possible overheating, but expect none. The hottest days in Wisconsin see temps in the 90s. Unlike Arizona with upwards to 30 degrees hotter. My driving will also be pleasure cruising on rural highways with no commutes in slow speed traffic.

[BimmerBreaker]

I'll bump this thread instead of making a new one. Great write up by the way.
I notice here the fan thermo switch is installed in the lower hose, in other threads I've seen it placed in the top hose.
I have an 85 degree C switch set up ready to go on my M54, up or down?

Thanks

I didnt see him say he put the sensor in the upper hose

That sensor goes in the radiator on the cold side and it triggers the electric pusher fan to come on earlier to keep temps down

[Jakechan]

I didnt see him say he put the sensor in the upper hose

That sensor goes in the radiator on the cold side and it triggers the electric pusher fan to come on earlier to keep temps down

I said,"I notice here the fan thermo switch is installed in the lower hose, in other threads I've seen it placed in the top hose"

This install for the Spal puller:
"⦁ Second Thermoswitch⦁ Since the original thermoswitch was left in place, a 36mm (not 40mm) water temp sensor adapter was installed inline on the lower radiator hose ($6)"

But, others use top hose fitting like this for example, using Spal switch
https://www.bimmerforums.com/forum/s...-and-questions

My guess is that either would be ok, but different temp rating switch would be necessary. Actually installation guide states switch should be in the "hot" side

[zellamay]

I said,"I notice here the fan thermo switch is installed in the lower hose, in other threads I've seen it placed in the top hose"

This install for the Spal puller:
"⦁ Second Thermoswitch⦁ Since the original thermoswitch was left in place, a 36mm (not 40mm) water temp sensor adapter was installed inline on the lower radiator hose ($6)"

But, others use top hose fitting like this for example, using Spal switch
https://www.bimmerforums.com/forum/s...-and-questions

My guess is that either would be ok, but different temp rating switch would be necessary. Actually installation guide states switch should be in the "hot" side

NO, either would not be ok. If you put it in the upper hose, it will always measure the hot water coming from the engine, and always be on.
If you put it in the bottom hose, it will measure water leaving the radiator. If the radiator is cooling the water sufficiently, such as when moving on cooler days, the fan will stay off.
When the radiator needs some help, such as hotter days while standing still, the water coming out of the radiator will be hotter, and the switch will turn on the fan.

[Jakechan]

NO, either would not be ok. If you put it in the upper hose, it will always measure the hot water coming from the engine, and always be on.
If you put it in the bottom hose, it will measure water leaving the radiator. If the radiator is cooling the water sufficiently, such as when moving on cooler days, the fan will stay off.
When the radiator needs some help, such as hotter days while standing still, the water coming out of the radiator will be hotter, and the switch will turn on the fan.

That's what I'm planning, hence wondering why the other thread had it on the top hose. As you say the fan would always be on, or worst case with a higher temp setting, would switch on too late.
Bottom hose it is....

[cngizbleevng]

The power robbed from the engine to spin the viscous fan has to be fractional. The power utilized would be for pulling x amount of air with the fan blades. The electric replacement fan would have to do the same indirectly requiring close to the same amount of power produced by the engine. The only negligable gain in power would happen with a viscous fan delete only without a replacement. But again, that power gain would be a tiny percentage of the total horsepower produced.

There was also mention of the viscous fan noise noting that it did not engage at startup. Mine definitely did and it produced a lot of blowing air noise with the hood open. I did a viscous fan delete only and all I hear now with the hood open is the engine.

I pulled my fan at the end of the season. This summer I’ll be monitoring my temp for any possible overheating, but expect none. The hottest days in Wisconsin see temps in the 90s. Unlike Arizona with upwards to 30 degrees hotter. My driving will also be pleasure cruising on rural highways with no commutes in slow speed traffic.

This is exactly what I've done. I'll be watching the temp gauge this summer.

I do have a question though, my thermostat is no longer going to the 12:00 position, so I'm guessing it's stuck, but is this offering a protective effect without the viscous fan? Will the car be less likely to overheat?

[BimmerBreaker]

This is exactly what I've done. I'll be watching the temp gauge this summer.

I do have a question though, my thermostat is no longer going to the 12:00 position, so I'm guessing it's stuck, but is this offering a protective effect without the viscous fan? Will the car be less likely to overheat?

Your car will never reach operating temp so it will get worse mpg, pull timing and hurt performance as well as run rich potentially damaging the cats long-term.

But I guess technically, sure, itd allow more time theoretically before an overheat. Thermostats can also fail closed though. Which would cause it to very quickly overheat.

The car is unlikely to overheat with a properly maintained cooling system. Contrary to popular belief, the germans who engineered this car actually had a clue what they were doing. The mech fan was a backup because they werent sure the electric fans were sufficient. Generation after ours went to all electric fans. Its not rocket surgery

[lapoune]

The car is unlikely to overheat with a properly maintained cooling system. Contrary to popular belief, the germans who engineered this car actually had a clue what they were doing. The mech fan was a backup because they werent sure the electric fans were sufficient. Generation after ours went to all electric fans. Its not rocket surgery

I tested mine (S54) with only the mech fan and temps got uncomfortably hot city driving\traffic situation, so YMMV...ended up going with a spal fan and a zionsville rad.