Fan Clutch Delete...

[Ripple7]

I'm in the process of doing a cooling system overhaul and I think I have convinced myself not to put the fan clutch back in. My aux fan runs fine and I'm not planning on putting a back up electric fan. 2002 525iT. Thoughts? Am I crazy for considering this?
Thanks!
Rip

[TriniSpeC]

no, but you car will get pretty hot before the aux fan kicks on.

[auaq]

Mine is laying on the carpet since last year. No engine overheating issues for me.

[prod0660]

have a fan on a switch or thermostat...it wont be a big deal if a fan is always running.

[ShapeShifter]

You need one of these.



2600cfm

[Fittsy1987]

let me know how it turns out im on my second clutchfan and its locked again so considering deleting mine aswell if just running the aux will be fine

[Ripple7]

Hiya auaq,
do you have just the OEM aux fan or an additional fan too? I have replaced thermostat, radiator, expansion tank, etc etc and am not too worried about over heating.

Mine is laying on the carpet since last year. No engine overheating issues for me.

[rf900rkw]

no, but you car will get pretty hot before the aux fan kicks on.

Incorrect.

[auaq]

Well, when I was in your situation about cooling issues with my car, I initially thought my clutch was faulty leading me to replace it with an aftermarket one - Imperial fan clutch. Didn't liked it cause it was loud, loud on cold start-up, loud in the city, loud on the highway, loud enough to ignore dogs and kids barking at my car. Hence, decided to remove it and store it farthest corner in the house. Never the less, it turned out to be my lower radiator hose temp sensor leaking coolant and inoperative. Replaced the sensor and everything worked fine.

There are two fans: one is the fan clutch and the other an aux fan as seen through the kidney gills. Make sure that your lower hose temp sensor is in good operating condition. Otherwise, if faulty like mine, the aux electric fan will be running at full speed all the time. The decibels of it running at full speed is a whole lot different level when juxtaposed to the fan clutch at full speed. If you are wondering how loud that aux fan can become .... just imagine you've aboard a plane and about to take off or imagine starting one of those jet engines!! Sounds like the SR-71 Black Bird is enroute to another mission over N. Korea, I say!

[dminaert]

I removed mine last year and have no issues since. Normal operating temperature with the fan hovered around 91-92. After delete temperature hasn't changed. Highest it ever gets is around 99 Celsius before electric auxiliary fan kicks on and that's in traffic.

[auaq]

I removed mine last year and have no issues since. Normal operating temperature with the fan hovered around 91-92. After delete temperature hasn't changed. Highest it ever gets is around 99 Celsius before electric auxiliary fan kicks on and that's in traffic.

Metoo!

[ojomo]

neighbor removed fan clutch on his E36 M3 and sitting in traffic, AC on full blast in 28C weather, car was perfectly fine. Also didn't guttershark (M62) remove his fan clutch and hes fine too?

[Graham E39 528i]

Let me see if I've got this straight. You guys are saying, the dudes who put in electric fans were wasting their time?

Sent from my Nexus 7 using BF.com

[Sac540i]

Im filled with doubt but subscribing to see where this goes...

[ND4SPDLSC]

You may be fine part of the time, but you aren't covering yourself. The fan is there for high ambient temperatures and for consistent cooling. You take out any factor of safety designed into the system. If the dash gauge isn't accurate, I wonder what is the temperature fluctuation seen in the heads. I can't imagine temp cycling to be helpful.

[Ripple7]

I believe rf900rkw has done fan deletes on his Z's without installing an additional aux fan. RF can you confirm this? I'll keep everyone updated on if a head gasket is in my future but I don't think it will be.

[bullard123]

Well, when I was in your situation about cooling issues with my car, I initially thought my clutch was faulty leading me to replace it with an aftermarket one - Imperial fan clutch. Didn't liked it cause it was loud, loud on cold start-up, loud in the city, loud on the highway, loud enough to ignore dogs and kids barking at my car. Hence, decided to remove it and store it farthest corner in the house. Never the less, it turned out to be my lower radiator hose temp sensor leaking coolant and inoperative. Replaced the sensor and everything worked fine.

There are two fans: one is the fan clutch and the other an aux fan as seen through the kidney gills. Make sure that your lower hose temp sensor is in good operating condition. Otherwise, if faulty like mine, the aux electric fan will be running at full speed all the time. The decibels of it running at full speed is a whole lot different level when juxtaposed to the fan clutch at full speed. If you are wondering how loud that aux fan can become .... just imagine you've aboard a plane and about to take off or imagine starting one of those jet engines!! Sounds like the SR-71 Black Bird is enroute to another mission over N. Korea, I say!

The inoperative sensor didn't throw a code??

[rf900rkw]

Okay, first off we need to make one point very clear here. There are two different aux fan controls. The early system is like the E36, two pressure switches in the A/C, two temp switches on the outlet (cold) side of the radiator. These are the cars that have relays and resistor packs. The newer version is computer controlled based on information from A/C pressure and radiator outlet temp sensor. Ala E46.
For the E46 style, there is nothing you can do to change the fan speed curves. This is okay because the system works very well as is. For the E36 version, many go to the earlier E30(?) temp switch to bring the fan on earlier. This is fine if it makes you fell all fuzzy. There are even E36 kits out there that upsell a bunch of addons if you wanna be total baller.

Now my cars. The Z3 series is like the E39 in that it splits across the E36 - E46 powertrains. Unlike the E39's the Z3 temp gauge sorta works, though it's still dampened.
The M Roadster is E36 style. I removed the fan soon after purchase in 2006. I put in an aluminum radiator in 2009 just cause I got a deal on a factory second. Added a supercharger in 2010. With the supercharger I preemptively replaced all the hoses, belts, and pulleys, as you can't get to them without removing the blower. No other changes. It's fine. The temp NEVER climbs above the thermostat point. The car has a recording data system, and coolant temp is one of the things monitored.
The Z3 coupe is the wife's daily. M54 / E46 based. The fan was removed a few months after purchase (It was starting to fail). It gets beat through daily rush hour to the tune of 18-20K miles a year. Zero temp problems. The Aux fan did fail on this car. The symptom was the A/C would go warm after being stopped for 20 seconds or so. I replaced the fan assembly with no further issues. That was three years ago. No further issues. This includes trips to DSS every year; last year in 110F temps stopped on the construction site Charlotte calls I-85. I get to drive and work on this car once every six months or so.
The 540iT was purchased with a Zionsville and two speed Spal. Quite frankly, the Spal sucked from the get go. I unplugged it and ran on just the aux fan for a long time. When I was doing other work on the car (chains), I found a lot of the problem. The dreaded PO that installed the Spal had wired it backwards. Hi to low, low to hi, and reversed to be a pusher. Yes, the #$% fan was wired to blow OUT thorugh the grille. I straightened out the wiring, and the Spal is back online. Now I have done extensive monitoring of the engine and radiator temps vs aux fan speed (all data available in INPA). Never a problem. The engine temp does not climb in the slightest, no matter the ambient or traffic. I've posted a large amount of those finds in various threads here. This summer I plan to wire up some LEDs so I can monitor which fan is on how much when.
The 318ti came with only an electric fan. It is unmolested... as much as it can be at the hands of a teenage girl.
The E46 323iT is not yet licensed, but has already lost it's fan.



While we're at it, let's cover why the engine should not warm at all with just the electric fan. We have to start with the thermostat and see how it works. The thermostat in our cars monitors the temp of the coolant exiting the engine. The thermostat starts by blocking the flow to the radiator, opening a port to the waterpump. Whent he thermostat is fully open, the port to the radiator is open and the bypass to the water pump is blocked, forcing all water flow through the radiator. In normal operation, the thermostat is in the middle, regulating some coolant to the radiator, some to the bypass. Thus the water entering the engine is a mix of hot from the bypass and cold from the radiator. This is a lot like the A/C system that makes full heat and full cold, then blends them to get the desired temp.

Now, when you stop dead in traffic, the only thing that changes from the cooling standpoint is there is no longer any air flow to cool the radiator. The thermostat still does it's job, mixing bypass coolant with cold drawn from the radiator. As the cold water out the radiator is used, the hot stuff enters and crosses without being cooled. As soon as the cold coolant is used up, the uncooled coolant reaches the cold side tank, the temp switch closes and the fan comes on. Thus, at the point the fan comes on, either E36 or E46 style, the engine temp has not risen one bit; still on thermostat regulation.


The only problem with running on the aux fan only is the reliability. If you are observant you can catch the failure before any damage is done. Keep in mind that, at least in this climate, the A/C demands the fan far soon the the engine. This means you'll see the issue with the A/C before the engine. IT also means that the fan will likely come on for the A/C long before the readiator temp requires it.

Bottom line, if given the choice between running a factory aux fan or a spal, I'll take the factory. I've had one fail. I've had and seen many Spal failures. Not the Spal motor itself, but the installation and connectors used.

[auaq]

The inoperative sensor didn't throw a code??

Only when I unplugged it (couldn't bear the loudness of the jet engine) did it throw a code. After replacement, the code went away and the gauge has always been at zhe 12 o'clock position since last year. No overheating issues for quite a long time, infact I've never had an overheating issues before. I would like to include that major cooling system overhaul was done long time ago.

[Cyrix2k]

Personally, I tried deleting the fan a couple summers ago and found my car to run too hot and wound up blowing an inline coupler on my heater hose (from the PO). It probably works fine if you run the A/C, but I don't and the temps need to creep up quite a bit to command the fan on. That and the A/C fan is not designed to cool the car. I used to use the A/C fan as the primary cooling fan on my e30 because the clutch fan physically does not fit in that car and it burnt up.

[auaq]

Wasn't there someone who talked about the ideal position of the fan - a puller type and a pusher type fan. After reading it some more made me thought that the pusher type fan seems to be more an effective and efficient design than a puller type. Just curious.

[Graham E39 528i]

Randy, thanks for the fascinating explanation. Awesome

That settles it. I have always hated the mechanical fan. I'm gonna delete it, and monitor the temperature with Torque running on my tablet (connected via a Bluetooth/OBD2 doohickey).

Here's a view of it:



I know you guys always disparage the e39 cooling system, but when it is working it has a lot of margin built into it. The only genuine mistake with my car I have perpetrated, in 5 years of being it's mechanic, is, after doing a cooling system overhaul, I refilled the coolant with 100% antifreeze. The mistake was due to fact I had gotten it into my head that the BMW stuff was premixed.

I ran that car for the whole summer in hot weather and traffic (with AC) and I never encountered a problem. Any automotive thermal engineer will tell you that 100% antifreeze is a big NONO. It's thermal conductivity is greatly compromised.

[rf900rkw]

Let me add one more thing. All of my cars have all the factory sealing and ducting in place. The little kicker panels, the belly pan, all there. And the ones I've had the radiator out of have fresh foam between the radiator and condenser. For an electric fan to be efficient, pusher or puller, all the air has to go through the core. If you give the air a chance to bypass the matrix, it will.

[Cyrix2k]

People have been deleting fans on the I6s for ages in the e36. Graham, you should be fine. That said, I'm running an M50 & e36 radiator in my e30 and it gets WAY too hot without a fan. This is the end of my datalog from yesterday - it was 70* out? Anyway, this is what happens when the car stands still. The datalog shows 5 minutes of time...

Let me add one more thing. All of my cars have all the factory sealing and ducting in place. The little kicker panels, the belly pan, all there. And the ones I've had the radiator out of have fresh foam between the radiator and condenser. FOr an electric fan to efficient, pusher or puller, all the air has to go through the core. If you give the air a chance to bypass the matrix, it will.

Mine too, the temp just climbs to high for comfort without the fan in place imho. Granted, the few days I ran without out it were about the hottest we get at 110 degrees or so. Running the A/C makes the fan kick in early, but I hate A/C...

[auaq]

Was it you Randy that talked about the pusher or puller type? I just thought that there was more air flow rate with the pusher type simply because of less obstacles in the path.