Delete E39 engine fan?

[cnn]

- Actually, most FWD vehicles still have 2 sets of fans:

1. The Aux fan in front of the condenser. This fan runs when the AC is on and the car is stationary

2. The "Cooling Fan" (or whatever name) just aft of the Radiator. This fan is controlled by engine coolant temp sensor.
Anyway, this fan is similar to the mechanical Fan Clutch in older BMWs.

[computiNATEor]

I don't know what FWD vehicles you've been working on, but I can't think of a single one that has a setup like that. My 95 Camry and every Honda I've seen have relay-controlled, computer-activated fans behind the radiator.

[cnn]

I don't know what FWD vehicles you've been working on, but I can't think of a single one that has a setup like that. My 95 Camry and every Honda I've seen have relay-controlled, computer-activated fans behind the radiator.

Most FWD vehicles have this setup, from Front to Rear:

Aux fan (for AC) ---> Condenser ---> Radiator ---> "Electric Cooling Fan" (this fan is conceptually similar to BMW Fan Clutch b/c it is close to the engine).

On some FWD vehicles the so-called "Aux Fan" is moved inside the engine and sits side-by-side with the "Cooling Fan", creating a "Dual fan" setup.
But the idea is the same: one fan is for the AC and another fan is for the engine coolant. There is some overlap in terms of their function as heat dissipation though.

[makenzie71]

Our ‘04 Grand Prix only had one setup behind I the radiator. Same with my ‘00 ZX3 focus.

That said, I have seen both setups...they both happen.

As an anecdote, I ran my E36 328i for nearly 60k without any fan whatsoever. I was running a 19x22 3-row aluminum radiator, though. The only time I ever overheated was one morning when it was about -10 outside and it froze the coolant in the radiator.

I think so long as the rest of your cooling system is in good shape then the system itself should be robust enough to handle things with only the aux fan. I’m going to be doing it as soon as I get the necessary crap sorted out...I’m siting on an Eaton M90 that I really want to setup with my 540 and I’m going to need every bit of spare room I can get.

[geargrinder]

Well. I doubt we have enough empirically data to decisively prove one way or another what statistically the majority of cars do or do not have, but, FWIW, my experience is with Nate's: far more cars now are going to a single fan, than a dual / redundant system. Doesn't mean some don't have 2 still, sure, and I'm sure some is specific-engineering-requirement-dependent (i.e. too much overlap of AC radiator / trans cooler / oil cooler /etc., or, weird ducting such that single-pusher doesn't get the whole rad, etc.) but, that's my observation and experience, so I'm going with "most nowadays seem to have one".

It does seem like in most cases, observing how they operate and how often and when that 2nd one comes on, the 2nd fan is the "Heavy AC" fan and is engineered to kick in mainly as Cold-AC support, that its function as a backup is there but really secondary. And that seems entirely consistent with our cars.

[sienayr]

Siena I wonder if your aux is dying or intermittent. Of course the facelift auto has that not-hugely-robust heat exchanger thing. The thermostat in that actually could be going bad for you?

Possible, I've seen map codes from time to time. Still too close for comfort for me.

[dannyzabolotny]

Just to chime in, I’ve been running without a clutch fan on my 2000 540it, and it’s been holding up just fine, even in 105°F weather here in Phoenix. I do plenty of stop and go traffic and keep the AC running all year round so the aux fan is always running. I like being able to drive around without the engine whooshing like a diesel garbage truck.

I also have an M5 cluster with an oil temp gauge so I keep track of that as well, and it never really exceeds the halfway mark (210°F).

This is on a mostly stock, automatic 540it with 207k miles and an original aux fan. I do have a new aux fan in the garage but this one keeps working so I haven’t swapped it out yet.

[geargrinder]

Possible, I've seen map codes from time to time. Still too close for comfort for me.

Hmmm.. . Thermostat age? Might want to keep an eye on that - maybe its not the fans but its the t-stat thats at fault... not opening all the way is a thing that can happen.

Just to chime in, I’ve been running without a clutch fan on my 2000 540it, and it’s been holding up just fine, even in 105°F weather here in Phoenix. I do plenty of stop and go traffic and keep the AC running all year round so the aux fan is always running. I like being able to drive around without the engine whooshing like a diesel garbage truck.

I also have an M5 cluster with an oil temp gauge so I keep track of that as well, and it never really exceeds the halfway mark (210°F).

This is on a mostly stock, automatic 540it with 207k miles and an original aux fan. I do have a new aux fan in the garage but this one keeps working so I haven’t swapped it out yet.

No Danny. That is not true, that's impossible, these cars were engineered for 2 fans and MUST have 2 fans and its impossible that you don't have one driving in conditions like that, and anyway you're taking your life into your hands and ruining everything for everybody and you're a liar and your car is going to blow up any minute now and leave you stranded and maimed or possibly dead plus you're an idiot and you suck.

(there, saved at least a hater or two their ridiculous rants..)

I always forget that you're runnin' around PHX givin' it the acid-test for fan-delete.

[computiNATEor]

Well, shoot. Might just have to leave out my mechanical fan when I get my car back together.

[tptrsn]

No Danny. That is not true, that's impossible, these cars were engineered for 2 fans and MUST have 2 fans and its impossible that you don't have one driving in conditions like that, and anyway you're taking your life into your hands and ruining everything for everybody and you're a liar and your car is going to blow up any minute now and leave you stranded and maimed or possibly dead plus you're an idiot and you suck.

(there, saved at least a hater or two their ridiculous rants..)

[Mach540]

Another reason to delete the fan....... The 'School Bus' whine of the mechanical fan......... Covers up the sound of the exhaust.

I'd take mine off, but my AUX fan is suspect. Sometimes runs... sometimes not.. I did take the mech fan off once and enjoyed the quietness, but it would start to get a little warm at the stop lights, and got just plain overhot when I let it idle in the garage for a while.

Got a new AUX ready to go in, but will wait til sometime when I get around to replacing the front bumper. Will probably add an Auxiliary Aux fan at the same time.

[Mike WW]

I doubt I'll convince anyone, but I'll chime in anyway. Starting with BMWs back in the E3/Bavaria days when the cooling systems were barely ok without A/C and marginal at best with it on, I have a different perspective. BMWs aren't made out of Detroit Wonder Metal, IE cast iron and long 6 cylinder heads are even more susceptible to warping if gotten too hot. Now more with Al blocks and threads pulling out of blocks. Now cooling systems are now much more robust, but failures do occur. If it's an occasional hobby car, WTF, you're the only one driving it, you should be on top of things, go for it. But it's a daily, with a spouse or kids or even a friend occasionally, let alone regularly driving it, you're foolish to delete part of the cooling system, at least this side of Alaska. Murphys law, you'll loan it out for the first time in 3 years which also coincides with the first time in 3 years it hits 105F where you live. And on that very day something odd happens, like the fan or even just fuse fails.

The School bus whine immediately above? It's a bad fan clutch, it's seized.

Redundancy is good, it makes for a much more reliable machine. And the PWM fans are not known for being bulletproof.

[geargrinder]

I doubt I'll convince anyone, but I'll chime in anyway. Starting with BMWs back in the E3/Bavaria days ......

As I said:

... these cars were engineered for 2 fans and MUST have 2 fans and its impossible that you don't have one driving in conditions like that, and anyway you're taking your life into your hands and ruining everything for everybody and you're a liar and your car is going to blow up any minute now and leave you stranded and maimed or possibly dead plus you're an idiot and you suck.

Just kidding Mike.

Bro, as a former owner of old school Fiats which would blow HG's and warp cylinder heads if you drove to the corner gas station on too-sunny a day, and an E3 'big six' 3.0s (MAN do I wish that that car hadn't been a rust bucket and that I still had it!)...

ALL THAT is true of those old mills.
Not so much (at all actually) for these cars.
Its totally apples and oranges, mate. You're living in "old man past" (said with all due respect as a fellow old-man).

M62 blowing HG's and warping heads is nearly unheard of, people routinely get away with minor to significant overheats.
Even M52/54 family motors aren't known for being THAT fragile.... "Oh No ALUMINUM!!!!" Whaevs bro, sure they are, but they ain't THAT fragile.

The nightmare stories on these motors always entail some variation of "I/wife/old-father/GF/BF/kid got the warnings and overheat but then continued to drive it anyway because actually stopping seemed like it would be boring and annoying." (for instance the thread from a year or two ago when a daughters-boyfriend killed a woman's 530 that way...)
Anecdotally my bud just overheated his 530i M54 after blowing the serp (and he DID drive it a mile home too) and the motor is fine.

Not that I'm recommending it, or guaranteeing that they are - as you say - Detroit bulletproof cast iron. But they ain't so fragile anymore.

Yes notable parts of the cooling system are still kinda crappy and BMW stuck us with poor quality radiator/tank supply, etc.

But on the other hand the warning systems are much more robust and early warning.
On those old cars "by the time you see the light you've just screwed your motor" (aka all the GG cars mentioned above).
With these things its the opposite. The threat of fully blowing the motor up is extremely low, unless you're a complete and utter jackass who will drive straight through screaming warnings left and right.

Now I will agree 100% with you on the 'family car' and 'who knows who might be driving it' angle.
Totally true. And we all have total jackasses in our families and friends I'm sure.
If I thought somebody who would drive through a "OVERHEATING STOP NOW" warning ever got behind the wheel, my choice would be different.

But this is a different question and argument. This is probably what should be in my explanatory post above...

Question 1 - Can the Aux fan do the basic job at all (keep up)? Absolutely yes.
Question 2 - Is the Aux fan robust enough to be driven on as a daily regularly without a high rate of failure? Is it reasonably reliable for that level of use? Absolutely yes.
Question 3 - Do you want to accept the minor decrease in fault-tolerance, given your environment, use patterns and driver profiles? Now that is entirely up to your situation and mindset...

As I have said a thousand times, I never push this solution on people. I just have to insist that you can't make up facts about Questions 1 & 2 purely because your answer to #3 is "yes I like having more security" (or need to have because I have morons driving my cars).

[jclausen]

Leave it alone spend your money on something your car may really need

[Kenny1958]

I ran for about 2 yrs with just the fan delete, relying on the aux fan but since getting the blower on it i added an electric fan from a volvo, run from an aftermarket controller.

[vinyldude]

M54 engines in X3 (E83) only have an electric fan.
It has the same water pump as other M54 based cars obviously where one could theoretically attach the normal fan clutch based fan. Although, I think the space would be an issue in X3.
Anyway, when I got my car I was disappointed to see no mechanical fan and thought the previous owner had done a fan delete before I learned that was not the case.

I suppose this kind of supports what others are saying about one (electrical) fan being enough. The fan operating points could be of course different in X3 than in other models with a secondary electric fan. And in 540i with its >100C cooling system I would personally take all designed air flow and operating redundancy I possibly can and would never go remove the fan.

[dannyzabolotny]

In a few weeks when it's 110ºF+ here in Phoenix, I'll log the coolant and oil temperatures every day that I drive the 540it and report back. No clutch fan, just aux fan. Completely stock cooling system with stock thermostat (things have been replaced, but with OEM equivalents, no upgrades of any kind). I don't drive the 540it gently either, I beat on it like it owes me money.

[StRaNgEdAyS]

FWIW, I had my AC over pressurize and blow out a couple of summers ago because of an Aux fan failure.. But then out winters would make many of you in snowbear country sweat. Our summers here in the northern half of the country particularly can and do kill unsuspecting tourists who underestimate just how intense they can be. I want to do a mechanical fan delete some time I'll replace it with an electric just because I want that redundancy in this climate.
Edit : I completely forgot about my first E39 throwing a fan blade.. Fortunately it went downwards and didn't damage anything else. But it sure make a nasty vibration.

Sent from my G8141 using Tapatalk

[Xavier1072]

Some one of the young guys on here who is super into his E39 should start making a G.O.A.T. list of comprehensive answers to FAQs for the forum, and start with this one and a bunch of other GearGrinder volumes. Well done my man!

Amen to that!!

[theWalkinator]

Question for your guys who have your mechanical fan converted to electrical fan, what should be the temperature range of the thermoswitch that goes in coolant pipe? Also, I would think it make sense that thermoswitch should turn on after thermostat is open, right? Then what is the thermostat opening temperature on our cars? I6 and V8.

[geargrinder]

That's the thing about the M62 - its not one temp, its between 80-105C basically... The factory doc says "it opens at 103C" but for various reasons, the exiting coolant will actually be more like 110C at that moment. Somebody will correct me on this but On the non-VANOS cars with the 2/3 speed setups, I think the factory switches for the Aux fan are something like 95C and 105C (measured at radiator outlet). 105C would be the "jet engine mode" all-hands-on-deck. I could go look up what the TU Aux PWM activation temps are.... but don't have the time at the moment. Couple of considerations...

One is there's arguments all over the web where the best place to put the sensor and what temp to set it for... Argument A is, you measure temp at the radiator Outlet, so that you're cooling to ensure a certain temp of cooler water returning to the engine. Argument B is, you activate at the radiator Inlet, in which case you use a higher temp activation, because by nature the inlet water is going to run hotter than the outlet temp. But rad outlet is the more sensible location IMO, and where on contemporary well engineered motors the mfrs tend to put it (and is where BMW puts it on all the modern motors).

The other is, how do you want your 2 fans to run... is the new one the 'primary' and you want it to come on before the factory Aux, so the Aux is the backup? Or the new one is the backup and you want the aux to run first? Generally probably something like 90-95C is the ballpark, if you want it to be the primary...

[theWalkinator]

That's the thing about the M62 - its not one temp, its between 80-105C basically... The factory doc says "it opens at 103C" but for various reasons, the exiting coolant will actually be more like 110C at that moment. Somebody will correct me on this but On the non-VANOS cars with the 2/3 speed setups, I think the factory switches for the Aux fan are something like 95C and 105C (measured at radiator outlet). 105C would be the "jet engine mode" all-hands-on-deck. I could go look up what the TU Aux PWM activation temps are.... but don't have the time at the moment. Couple of considerations...

One is there's arguments all over the web where the best place to put the sensor and what temp to set it for... Argument A is, you measure temp at the radiator Outlet, so that you're cooling to ensure a certain temp of cooler water returning to the engine. Argument B is, you activate at the radiator Inlet, in which case you use a higher temp activation, because by nature the inlet water is going to run hotter than the outlet temp. But rad outlet is the more sensible location IMO, and where on contemporary well engineered motors the mfrs tend to put it (and is where BMW puts it on all the modern motors).

The other is, how do you want your 2 fans to run... is the new one the 'primary' and you want it to come on before the factory Aux, so the Aux is the backup? Or the new one is the backup and you want the aux to run first? Generally probably something like 90-95C is the ballpark, if you want it to be the primary...

Yes, I want to use it as the primary fan, I am asking because I see there are generally 2 temp on-and off ranges, 200F/185F (93C/85C), and 175F/185F (79C/85C), I don't want the fan on all the time so I would think go with 200F/185F themoswitch, but based on your evaluation, the range still seems to be on low side, isn't it?

Another question related, what electrical fan CFM rating and amp draw rating should be sufficient to cool the engine and not put heavy load on alternator/battery?

I am considering this kit: https://www.amazon.com/Performance-R...mostat+Kit+200
Themo adapter 34MM: https://www.amazon.com/Dewhel-Alumin...Sensor+Adaptor

[geargrinder]

I think that should probably work.

What you'll find is probably it will be how the factory Aux fan kind of works when you mechanical delete... it will be off, then the t-stat will open up and the 110F water hit the rad, come out the other side, and the fan will first come on HIGH... it'll run at that speed for a minute or so then drop back down to low and be fine... A higher set of numbers means it might only be in "low" when it first kicks in under normal conditions.

Just looked it up... factory points for the M62TU are more or less (theres a whole curve but these are key points..):

80C - 10% duty cycle
95C - 50% duty cycle
105C - 90% duty cycle (basically max)

So yeah, probably thats a little higher than the switches you've found. Even that factory setting 'comes on hard' because as I said, the first gulp of water tends to come through hot before the fan cools things and the whole system starts to cool down a little.

You know you could just get the pre-TU factory sensor and retrofit that to FrankenSystem probably...

[Mike WW]

I just remembered something that might be of note. On my E36 the fan clutch was dead a year or two ago. Aux fan worked ok and the buffered gauge never moved. But when I replaced the fan clutch I noticed the in town A/C performance was better. Not night and day, but noticeable. YMMV.

[geargrinder]

Sounds right.