If I was to do a spal, I would look very hard at doing its own temp sensor in the lower hose connected to a Pwm controller, much like the E46 does.
Randy's solution would be ideal... I don't really like the fact that I have both fans relying on the single radiator temp switch, but that was the simplest way to do it.
I could take pictures but there wouldn't be much to see (I ran the wires alongside existing wires, wrapped in black electrical tape). But I can tell you where I put stuff:
- relay placement: in the compartment where the DME is (there is also a block of 12v power there to use for the fan power).
- relay trigger power: 12v switched power wire (so fan will not run without ignition on): runs across the firewall behind that black plastic structure that has other wiring in it, then over to the 20-pin obd connector where I spliced into one of the wires (the switched 12v one, I think to pin 16).
- relay trigger wire ground side: runs out of compartment through grommet past shock tower to the radiator temp switch. When temp switch activates, it grounds the trigger circuit in the relay. This coil then switches the high-amp fan power circuit on:
- fan power source to relay: in DME enclosure, block of available 12V from battery (be sure to use fuse!!)
- fan power source from relay to fan: also runs out of compartment past shock tower down to the fan.
Last edited by raubritter; 12-11-2017 at 09:10 AM. Reason: fixed relay info
Anyone interested in adding an electric SPAL should use the SPAL 30102049. It's a curved blade (much quieter) puller, and flows over 25% more air (2040cfm) than the old flat bladed ones...and yes, it's still thin enough to fit. You'll also want to try and create the best low pressure zone directly behind the radiator, so you'll need to construct some sort of shroud (the stock one doesn't help if the fan is inside it). I had a local metal shop fab up a shroud using 1/2 inch, square, aluminum bar stock, and a thin aluminum sheet...it cost me $40 including tip.
It's up to you...not really necessary. I did it because I'm boosted, and for some extra peace of mind.
Do NOT do this! This is completely redundant! The temp switches in our quirky, little, old cars are prone to failure also...so installing a "backup" fan on a switch that is as likely (or more likely) to fail as your main fan (the aux fan) is ridiculous. You should be running the SPAL/backup fan off of its own sensor in the lower hose...it's a flow-thru metal housing, with a bung to accept switch sensors. Very inexpensive, and available through companies like Jegs/Summit/etc.
Close. You want to completely isolate any "backup" mechanisms in a system. So, the "backup" fan should be COMPLETELY on its own circuit...not sharing any part of the main fan's system. You want an in-line, flow-thru housing placed in the lower radiator hose with its own temp switch/relay for the "backup".
^^^THIS!!!!!! x 1,000,000!!!! Although, I don't think a PWM controller is necessary if you're just using the the SPAL as a backup fan. If it's truly intended to be a backup system, then it's safe to say that when it kicks in, it's an emergency (or close to being an emergency)...It should be running full tilt to prevent any serious problems. The E46's run the PWM because they use the electric fan for all of their cooling...hence having it operate at various speeds.
No. Coolant temp coming out of the engine would be the upper hose. The lower hose is the cold side...coolant entering the engine. Here's a quick breakdown of how it should happen:
You're driving along in the Arizona summer heat, and come upon a traffic jam. Temps are starting to rise. Little do you know, but your cooling system is faulty, so things are about to get HOT! As the temp in your engine climbs (and by now the thermostat is open), the temps in your radiator are also climbing as hot water from the engine is being pushed through from the upper hose/hot side, across the elements to the lower hose/cold side...but since you're not moving, there is no airflow to cool the water in the radiator. So, the fan switch on the cold side of the radiator is now receiving hot water...but the switch is dead, so your aux fan will not be activated (nor will any backup fan using this circuit)! The aux fan itself is functional, but it is receiving no signal from the faulty temp sensor/switch, and is completely useless. At this point, you have NO ability to cool the water/cool the engine...unless you have a backup fan on an independent isolated circuit. If you have a backup fan, connected to the aforementioned in-line flow-thru housing with a temp sensor/switch, installed in the lower radiator hose, that sensor/switch will trigger once it receives the unregulated hot water coming out of the cold side of the radiator, and will activate your backup fan.
Looking back at that example, can you see why having a backup system rely on the same circuitry as the main fan is a bad idea? If the main temp switch fails, you will have no working fans!
As for leaving the aux fan "in the circuit"...I'm not sure how to answer the question as posed. You should definitely have the aux fan in place, and connected as from the factory. The SPAL/backup fan should be on its own, completely separate circuit.
Hope this all helps.
Last edited by danomite; 12-09-2017 at 07:54 PM.
"You don't win silver....you lose gold."
Excellent series of replies - many thanks.
The flow-thru housing that would go into the lower hose - given the ID on our hoses, does anyone have a part number? ... and I assume using such, it will come with a temp sensor, so just go with the connectors on it, instead of trying to make use of the bimmer part?
But I fully agree with the notion of the independent system... I think the only thing I'd add would be: some led for the dash, to let you know that you're running on the backup system.
Again: many thanks.
Just a follow up: looks like the ID of the lower hose is 38mm, at the two ends [that's what's in the parts description], but it also looks like it is smaller in the straight stretches that one might want to insert the sensor into... anyone have a dead one that they can slice cross-wise and measure the ID at that point? [I just checked my parts shelf and have no old one, nor a new one].
Last edited by gmushial; 12-10-2017 at 12:29 PM.
Measure the wall thickness and subtract it (x2) from the straight section o.d.? You'll need calipers.
danomite: I completely agree. I've never liked having both fans hooked up to one temperature switch (though if the aux fan failed it would help in that case at least)... What is the trigger temperature for your lower radiator hose switch? Could a standard BMW temp switch like the one in the radiator be used?
I'm definitely interested if you guys can post some part numbers/links for this... I'm searching now for this pass-through housing, but please post if someone finds it.
Is this what you're talking about?
https://www.summitracing.com/parts/atm-2283/overview/
or
https://www.summitracing.com/parts/mio-mmwhs-38-bk/overview/
Those should work with 1.5in / 38mm hoses. There are related options on this search:
https://www.summitracing.com/search/...ender-fittings
So you'd cut your lower radiator hose and insert this in-line... Coincidentally it's about time for me to change my coolant anyway.
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I'm finding a gazillion housings on eBay - just don't know the diameter to buy... but all are cheap. Though one then also has choices on the temp sensor threading: 1/4", 3/8", 8mm, 9mm, 10mm... but need the hose ID before anything else.... but once I have a parts collection together, will happily post the details. ... but we need someone with an old hose to measure the ID in the straight section [though yes, one could do the OD - 2x the thickness... but currently I don't even have a new hose to measure :-( ].
- - - Updated - - -
Yes... though the eBay prices are about 1/4th as much ... though the 38mm is the question, ie, the radiator end is 38 ID - that's what all the specs say... but the section of the hose that one could splice into is clearly smaller... and hence the plea for someone with an old hose to slice it and measure.
I'd start with the SPAL, find a temp sensor that works for that, then find a housing that works for the temp sensor and hoses. I can measure some hoses later for you if you don't get an answer soon.
Just an idea - measure the hose's OD at the radiator opening then measure the OD where you want to splice in the sensor housing. I'm willing to bet that while it may be a little smaller in the "center" of the hose, a 38mm ID housing would still work. Plus, you want it to be a nice tight fit, you don't want the hose clamp to do all the work making the seal.
Last edited by BimmerBreaker; 12-10-2017 at 12:37 PM.
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Fan wiring "Spal 185FH" contains all wires, connectors, relays, temp sensor. Turns on at 185F, turns off at 165F.
Spal sensor is 3/8 NPT threaded, so most of cheap ebay housings (as one in picture) will not work (or you can try to rethread them).
According to my research 38mm OD should be ok, so https://www.summitracing.com/parts/atm-2283/overview/ and http://www.steigerperformance.com/PRODUCTS/sp40001.html should work. (Saying should, as I haven't done the conversion myself yet.)
Last edited by deni2s; 12-10-2017 at 12:56 PM.
If you're going to replace the stock system with a sensor-driven electric fan with a proper shroud, I have no issue with that. That's not a bad way to go. I thought you were advocating removing the cooling fan and having nothing else there because of the liability of the clutch fan and the fan itself.
That is the initial recomendation. Now the conversation has evolved into suitable systems that could operate as a backup in case the aux fan fails
I just helped a friend get a 2000 540i home from San Diego. Previous owner had the fan clutch seize and explode. Left a huge hole in the hood and cut both main radiator hoses on it's way out and damaged the radiator. Fan clutches are a potential source of catastrophic failure and they aren't always easy to diagnose when they are on their way out. If one chooses to blindly replace it every so often that is fine, but it's much safer for most people to delete the fan and clutch and not worry about it at all. The fan clutches fail a LOT more often than the aux fans do and when the aux fan fails you have time to pull over before damage occurs. If the clutch fails, it messes stuff up.
And now that we are working on establishing a good backup system with an electric fan, there will be absolutely no reason to run a clutch fan on any Z3 in the near future... imo anyways...
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Just remember that electric fans are not without their faults. I've seen on several cars instances where an electric fan seized up, caused the motor to overdraw current and meltdown the wiring harness from the fan all the way to the fusebox. Very expensive if that happens. With a high capacity fan, it's important to put in a fusible link or a circuit breaker to cut the circuit in case the fan seizes.
Also remember that without a real water temp gauge, you don't have a whole lot of warning before you have to shut the engine down. I've had cooling system failures on several cars and was able to prevent significant damage by turning the heat on full hot and getting the car shut down as quickly as possible. Any excess running of the engine on a failed cooling system is a recipe for disaster.
If you could, that would be great... ... my concern on the ID question: from memory, and from pictures, there is a significant different in diameter at the ends vs the middle, maybe as much as 6 or 8 mm... and yes, very much agree with you on the let the snug fit of the hose hold it onto the fitting and let the clamp act as a backup... if you can't get the hose on, then that goes out the window. :-(
True... nothing is perfect. But wire a fuse in series with the fan and an led around the fuse and one would be good to go. ... but I believe the evolving theory is: use the existing aux fan and the existing sensor and wiring, as is. Which is what I've been using since last Apr or May. And install the SPAL on the inside of the radiator with a separate sensor in the lower hose, which in theory would only come on/be used if the aux failed. So in theory, if the P of failure of the aux fan is like 10^-5 and the SPAL is likewise, then combined, the likelihood of both failing will be less than being abducted by purple (not green) Martians on a Tuesday and after lunch, but before dinner.
I notice that later on, yes, bimmer moves the sensor to the connector - which would make it easier to make a use of... though the problem I see is: our lower rad hose seems to be unique, ie, only fits the I-6 Z3's... unless you happen to know of a more modern hose that would still connect to the t-stat housing and likewise the rad?? Is there such a beast [thereby splicing the housing into the middle of the lower hose]?...
Also, if one isn't going the PWM route, but an binary on/off system, what would you set the trip point at temp wise? On at 90C? 95C? Given that this would be going into the lower hose, and by intent should only come on either a) when the aux fan has failed; and/or b) the aux fan wasn't cutting it, and more air flow would improve a high temp situation [though I think I'd like to design for "A" and not "B" - but could be wrong] ??
This might be a case of: it depends on which brand of hose you use, ie, the cheapest AutoZone generics, seems to run 1.5" from end to end; but like a Rein's, looks like it's 38mm at the radiator end, but measuring from the screen pic, looks like it wants a 34 or maybe even a 32mm splice. So it might be a case of buy a hose to insert the splice into; cut it, measure it, buy the splice/sensor to match; and them swap the old hose out and swap the new one in.
s-l1600.jpg
edit: I ordered a Reim's lower hose, and will build around it.
Last edited by gmushial; 12-10-2017 at 11:02 PM.
It seems that as long as your backup fan comes on before the engine gets too hot, you've accomplished your mission. Choose 80 degrees C or something a little higher. It will only help if you are sitting in traffic.
I've read this thread with interest, after having removed the clutch fan and closed the hood. I understand the desire not to lose an engine, and realize we do not know exactly how hot the engine might be given the way our temperature gauges are set up. That said, how many current production cars run more than one fan? How many know of someone whose electric fan has malfunctioned vs. a clutch fan exploding?
Wayne
1998 M Roadster
1994 Honda ST1100--sold
2017 Yamaha FJR1300ES
Zfest 2014. Two certified exploded fans requiring tow and new radiators at a minimum, and a third suspected failure on the home trip. No reported electric fan failures.
I have seen the aux fan fail once. I have seen MANY Spal type installations fail. Not the fan, the wiring and connectors overheat. Even the connector on the fan will melt if run near 100% duty. This is not something a fuse will protect
As far as two fans, it's not by any means a given. Most factory twin electrics are done due to packaging, demanded by the wide low radiators to fit the modern hood line. Our powertrain was designed and certified with one fan, the mechanical. The problem is the clutch fan is a lethargic antique design that can not keep up with the quickly changing demands of A/C. So BMW had to add a modern electric fan to the A/C equipped cars. All bmws with just an electric fan, starting with the M44 Z3, have but a single fan.
As far as why my postings are sporadic and terse, I'm having a bit of a health issue that is currently sapping 100% of time and energy.
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