Fan Delete and Now Overheating

[rf900rkw]

One of the more astute observations. The question is if the mechanical fan would do anything to change the air flow characteristics. Or would it just luft in a stagnant pocket of air. I did actually put a mechanical fan back on my coupe last year for a week. Since I'm operating in the real world rather than controlled tests, the results were inconclusive. I think it helped a little bit, but it wasn't a big change. I decided to go after the flow path instead. I can't even fit a fan to either car, so no more testing of that.

[deni2s]

I did actually put a mechanical fan back on my coupe last year for a week. Since I'm operating in the real world rather than controlled tests, the results were inconclusive. I think it helped a little bit, but it wasn't a big change. I decided to go after the flow path instead. I can't even fit a fan to either car, so no more testing of that.

That day when someone decides he needs tests for stock config (after 20 years of everyone using it)...

[BimmerBreaker]

If the main issue is airflow, how can that be improved?

My M Coupe got to about 3/4 on the gauge once in some canyon roads in Cali, MM underpanel with no ducting at that time and stewart water pump. Probably a recipe for disaster looking back on it, but now Im a bit more careful. And Ive added ducting on the MM panel.

[rf900rkw]

Denisss, it's called scientific procedure. When you get unexpected results, you recheck your baseline.

Graham. that's to be determined. Potentially more air in via a chin "scoop". More efficient use of the air via larger radiator surface area, and most importantly working on air flow exit. I think that's the biggest issue, the M bumper lets too much air under the car. Need a nice low pressure area there.

[BimmerBreaker]

I must admit, that makes me wonder about using the mechanical fan simply as a way to create a low pressure zone behind the radiator to help with airflow... At speed the mechanical fan may simply get in the way and generate turbulence but at low speeds I wonder if it serves a purpose

[gmushial]

That day when someone decides he needs tests for stock config (after 20 years of everyone using it)...

I suspect there are any number of things that you rely on on a daily basis, that you have zero idea how close to design limits you're operating them... yet you happily, blindly continue to use them... if one is going to alter a system, it is very very nice to know what one is quantitatively altering away from.... conversely, not knowing such is the whole basis of a huge segment of the after-market parts business; chromed lug nuts increase gas mileage because they're more aerodynamically efficient; likewise trunk lid spoilers that increase downforce allowing you to go around corners faster (at 35mph) etc... the due diligence that Randy has put forth to understand the cooling system is admirable.

[rf900rkw]

But low speed is not the problem. One bit of hear say evidence I have noted is the track guys that say they can only go 10 or 15 minutes before the oil temps get too high. The most likely source of the oil temp is from the cylinder head. When the cooling system packs in, saturates, the oil becomes the coolant.

[raubritter]

...the M bumper lets too much air under the car. Need a nice low pressure area there.

How about those vertical spoilers perpendicular to the airflow that some cars have underneath the front bumper? Like on this corvette:



Also, speaking of corvettes... What magic is going on that they can cool that V8 with such a tiny air inlet in the front?

[Mr Bingley]

There's always this option:

[rf900rkw]

How about those vertical spoilers perpendicular to the airflow that some cars have underneath the front bumper? Like on this corvette:



Also, speaking of corvettes... What magic is going on that they can cool that V8 with such a tiny air inlet in the front?

I put a Gurney flap at the back of my MM first thing. I have something much more elaborate planned for the other car. But alas my car working energy is on vacation for the next few months.

[cleanerPA]

Like Randy was saying, managing airflow is crucial. Making sure that all of the underbody panels are intact and well sealed, making sure the air goes where it's supposed to, makes a big difference.

That's how the pictured C4 Corvette cools properly- the opening is not that big, but that air dam and the placement of the opening is such that you get a good airflow going into the radiator. Of course, due to its placement, it is crucial that the opening is kept clean of debris that inevitably builds up from use. The same thing happens with the watercooled Porsches- 996/986 and newer- the radiators get gunked up with leaves and debris over time.

[gmushial]

There's always this option:

ah... the modern ugliness ... have no idea how the gaping mouth design ever got beyond the bathroom... someone forgot to flush I guess... :-(

[jajou318]

I've had a spal harness melt along with the fuse. Went back to mechanical. The car already had a spal up front for aux.

We shrouded the radiator and installed the metal belly pan. Been fine since.

Not sure why the spal harness melted.

Sent from my LG-LS997 using Tapatalk

[deni2s]

Custom shroud owners, can you share pics of what you have for inspiration, please?

[Mr Bingley]

Custom shroud owners, can you share pics of what you have for inspiration, please?

Custom Zionsville shroud (with radiator). Fan and slats are offset for supercharger. Provision is included for S54 factory oil cooler.

[danomite]

Your overconfidence confuses me.

First of all I don't think narrow curved blade design fan will allow me to switch to bigger radiator (maybe I will give Zionsville another try) and fit supercharger in future.
Yes, the plan is to use Spal fan as main fan (as substitute to clutch fan, which currently is main fan). The sensor switch of the aux fan is on top of radiator, spal sensor goes to lower pipe, which should be cooler, hence the lower temp switch. And lower 88C temp in aux switch in my opinion is when it's already too hot (like an emergency). Will try my way (heard a lot of good feedback regarding this setup), maybe will add PWM later.



Couldn't find anything on their website and seems they have shops in USA only, will be expensive shipping/customs fees. I don't really see any problem with buying $5 housing and rethreading (+$10 for rethreading tool). Sensor was already included in Spal wiring kit.

Why not? That's exactly what I have...and I'm supercharged. The curved blade fan is the same size as the flat blade, but it moves more air and is quieter.

You do realize that your current aux switch is 91/99C, right? Our engines run at about 92-95C...if you're in a situation where there is no air flow, and your motor needs cool water from the radiator, BMW decided that 91/99C is still within the safety range for the aux fan to provide sufficient cooling. I simply lowered the aux fan switch temp to 80/88C so that it does a little extra cooling preemptively.

I don't see any problem with that either...I just said that you can find adapters or properly threaded housings. If you're unable to find them, I'm sorry.

Agree. What's wrong with replacing the inexpensive part every couple years and run in stock configuration? It is redundant protection that we only run away from when it ages and fail prematurely.

I replaced my clutch fan years ago only to have it explode a year later. In that case I believe that bad motor mounts allowed the fan blades to contact the radiator when I sucked air foolishly racing a 911 twin turbo with no gas in my tank (light on)--either that or the boost pressure bypass valve kicked in--or I was just pushing to hard with a new supercharger--anyway, the new fan exploded, that's for sure. Since it took out my new S54 radiator, I went with a custom Zionsville set up that deleted both the clutch fan and the aux fan in favor of a Spal puller fan and shroud. As I recall, the Spal runs off the same (but new) fan switch in the side of the radiator with the resistor set up (also new) for low and high speeds as the aux fan. I also replaced my motor and transmission mounts, and have since had to replace the passenger's side motor mount again. I highly recommend keeping up with the motor mounts--especially on FI cars. The Zionsville set up is incredible--it's how the car should have come new.

^^^ This!!!

Terry, the fan doesn't only fail/explode when its old...you never know when they're going to fail...hence people removing the ticking time-bomb from their cars. Feel free to do as you see fit...I just always advise against adding something that is unnecessary and hazardous.

Custom Zionsville shroud (with radiator). Fan and slats are offset for supercharger. Provision is included for S54 factory oil cooler.

Mine is similar to this, but for the stock radiator on my supercharged M54 3.0. However, since my "overconfidence" confuses some people, I think I'll just keep the pics to myself...wouldn't want to cause further confusion.

Randy: I should've listened to you...should've just ignored 'the believers'.

[deni2s]

Why not? That's exactly what I have...and I'm supercharged. The curved blade fan is the same size as the flat blade, but it moves more air and is quieter.

According to diagrams on Spal website it's not the same size, there is narrower fan with fat blade.

You do realize that your current aux switch is 91/99C, right? Our engines run at about 92-95C...if you're in a situation where there is no air flow, and your motor needs cool water from the radiator, BMW decided that 91/99C is still within the safety range for the aux fan to provide sufficient cooling. I simply lowered the aux fan switch temp to 80/88C so that it does a little extra cooling preemptively.

You do realize that temp in lower pipe will be lower than on top of radiator where aux switch is because of physics? So if 91/99C is BMW safety margins on top of radiator, then on bottom it should be less.

[rf900rkw]

That would only be true in a static situation. I suspect that under low flow idle conditions, the corner with the fan switch is stagnant. No matter. We are not concerned about the temp in the upper right corner of the radiator. We are concerned with the temp of the coolant returning to the engine. The lower hose is the best measuring point.

[CarnageGraphics]

I have a question you may be able to answer rather quickly for me.
I have an '01 330xi, automatic. HATE the fan clutch noise...reminds me of a school bus, and I'm 41 years old.
I was thinking of getting a fan assembly from a manual (oem electric fan) to replace it, question is; Can I just unplug the current smaller fan in front of the rad, and plug in the electric OEM fan in it's place?

I'm thinking it's the same function, just larger volume of air being moved...right?...lol

[rf900rkw]

I can't tell you if the plugs and fuse/wire ratings will match up or not. But I can tell you I run my daughters 325 with just the front fan. The mechanical fan was removed at purchase. It's been fine for 70K miles of semi-clueless female driving.

[danomite]

According to diagrams on Spal website it's not the same size, there is narrower fan with fat blade.



You do realize that temp in lower pipe will be lower than on top of radiator where aux switch is because of physics? So if 91/99C is BMW safety margins on top of radiator, then on bottom it should be less.

That would only be true in a static situation. I suspect that under low flow idle conditions, the corner with the fan switch is stagnant. No matter. We are not concerned about the temp in the upper right corner of the radiator. We are concerned with the temp of the coolant returning to the engine. The lower hose is the best measuring point.

^^^ THIS!!! x 1000000

Also, I don't know where to begin!!!

deni2s, I don't know if you're just trolling, or if you really don't get it. The radiator is made of a central cooling element with fins/vanes, and two end tanks. The water flows from the hot side to the cold side. So, by the laws of physics, which you so eloquently referenced, the water in the cold side tank is roughly the same temp from top to bottom...therefore, the location of the aux fan temp switch on the cold side is negligible. BMW chose the temp range AND location of the aux fan switch, for it to operate within the "safety" range...so by moving it into the lower hose, you'll only be creating extra work for no "real" benefit/reason (you may see a few degrees difference, but that's of no consequence). Also, you keep referencing the 91/99C switch, after I said that the 80/88C is the one to use...I've addressed that below.

You argued before "And lower 88C temp in aux switch in my opinion is when it's already too hot (like an emergency)." which is complete nonsense! It's an 80/88C switch!!! That's over 10 degrees lower on both the low and the high triggers!!! First of all, I don't know of anyone running BMW switches that are lower than the 80/88C switch on our motors (because it's unnecessary). Secondly, if they did, the aux fan would be on A LOT since our motors run at about 95C...and the thermostat constantly flows a small amount of "hot" water into the radiator. Third, if you want to go even lower than 80/88C for the aux fan...what in the world are you going to run the main fan at??? 70??? 60??? And where are you even going to mount the temp switch for the main fan??? You're basically going to have at least one fan running at all times!!! Hahaha!!!

I'd really like to hear details of the exact setup you're planning on running. Main fan type, main fan location, main fan temp switch range, main fan temp switch location, main fan mounting setup, aux fan, aux fan location, aux fan temp switch range, aux fan temp switch location.

Staying tuned...

[Tom Liberatore]

All this fan delete chatter agitated my fan and shroud to the point where they attempted a spontaneous reattachment but couldn't open the hood.

[deni2s]

The water flows from the hot side to the cold side. So, by the laws of physics, which you so eloquently referenced, the water in the cold side tank is roughly the same temp from top to bottom...

According to my physics knowledge, hot will always tend to top, and cold to bottom, not like from one side to other side (which happens too due to water pump, not the cold/hot difference)... That's why hot pipe is connected to the top of rad and cold pipe to the bottom. Or at least that's how I imagine it is... as I actually haven't seen radiator out of the car yet (will do full radiator/cooling system replacement tomorrow on other z3 to stock config). So truth is in between - temp switch is in hottest (top) corner of cold side and I believe there is temp difference between top and lower corner of cold side.

I'd really like to hear details of the exact setup you're planning on running. Main fan type, main fan location, main fan temp switch range, main fan temp switch location, main fan mounting setup, aux fan, aux fan location, aux fan temp switch range, aux fan temp switch location.

Main puller fan Spall the narrowest one (already bought by Dwight from Zionsville recommendation, it's like 1600 something CFM if I remember right) with Spal wiring and Spal switch in lower pipe. Switch turns on at 85C, turns off at 73C. Stock aux fan/switch/location. Maybe later will upgrade rad to Zionsville (or other), then Spal fan will probably placed offset, to clear the space for potential supercharger in future. This setup was already tested by other z3 owner, he seemed pretty happy with the setup, so I don't expect any major issues.

I never said I want to run aux fan lower than it is in stock for my config...

[BimmerBreaker]

Some good visual evidence for why a fan delete is recomended...

[deni2s]

I just replaced radiator, thermostat and most of the pipes in yellow z3 to stock spec. I measured the OEM lower radiator hose #11531436988 and it is about 39.5mm in OD almost everywhere, except near the radiator where it's much bigger. So 38mm housing for temp sensor should fit just fine. I think earlier in the thread someone mentioned 32 mm would be the right one to fit properly...