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Thread: Fan Delete and Now Overheating

  1. #101
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    I had the OEM connector fail. Made the aux fan (which when I bought the car was not functioning) made an exciting loud humming sound. One deutsch connector later (well, two; the body shop fucked up the first one) and I had a working aux fan.

  2. #102
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    Relay failure must be considered as exciting as fan failure. There also didn't seem to be too many replacements when I was looking for a relay, ymmv.

  3. #103
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    For those planning to add a spal fan, here is a useful diagram I found on the internet somewhere for the relay wiring:

    fan relay.gif

    I had never messed with relays before doing this, so here is a summary of what is going on for others who are new to this:

    Basic idea is the relay trigger circuit is powered (85 on relay) by a 12V switched source in the 20-pin OBD connector (so fan can only come on when ignition is on). The other half of that circuit (86 on relay) goes to the temp switch. When temp switch hits target temp, switch closes the trigger circuit, activating relay coil.

    When relay is activated, the fan power source (fused 12V from battery, to 30 on relay) is connected to the fan through the relay (87) and the fan comes on.

  4. #104
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    Quote Originally Posted by rf900rkw View Post
    Most factory twin electrics are done due to packaging, demanded by the wide low radiators to fit the modern hood line.
    I worded my question poorly. My intention was to ask if any current production cars have both pusher and puller fans, forgetting how many do run two pushers or pullers.
    Wayne

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  5. #105
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    Electric pusher in front of a mechanical puller has been done, both BMW and Mercedes to meet the A/C demands. Honda used to have a puller on the radiator and a pusher on the separate A/C condenser back in the dark ages of dealer installed A/C systems. I know of no car that used an electric pusher and puller on the same section of cooling matrix. I certainly would not waste the space with it.

  6. #106
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    Quote Originally Posted by rf900rkw View Post
    Electric pusher in front of a mechanical puller has been done, both BMW and Mercedes to meet the A/C demands. Honda used to have a puller on the radiator and a pusher on the separate A/C condenser back in the dark ages of dealer installed A/C systems. I know of no car that used an electric pusher and puller on the same section of cooling matrix. I certainly would not waste the space with it.
    Though two fans subtending the same area of a radiator, but where one is the primary system, and the other is a fallback, backup... that's a different story, correct? Equally: I'm assuming any degradation to the cooling function of the primary of having that 2nd puller fan which it has to blow through, will be acceptable... correct?

  7. #107
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    Quote Originally Posted by gmushial View Post
    Not sure why one would want to try to rethread the temp sensor - why not just find one that fits; or conversely, have a sensor and find an housing that fits it? ...
    Rethread the 10$ ebay sensor housing, not the temp sensor, instead of buying 40$ housing (which are available in USA only, so with shipping and custom fees to Europe in my case it's like 80$ total).

    - - - Updated - - -

    Quote Originally Posted by cleanerPA View Post
    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.
    Spal wiring I mentioned earlier has a fuse included...
    Last edited by deni2s; 12-11-2017 at 06:25 PM.

  8. #108
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    Another thing to not forget to those who rely on aux fan only - check that it's been wired properly from factory, both my cars were wired improperly.

  9. #109
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    Quote Originally Posted by deni2s View Post
    Rethread the 10$ ebay sensor housing, not the temp sensor, instead of buying 40$ housing (which are available in USA only, so with shipping and custom fees to Europe in my case it's like 80$ total).

    - - - Updated - - -



    Spal wiring I mentioned earlier has a fuse included...
    Don't rethread either: there are enough choices on both to have a match (btwn housing and sensor), and get the right size for the actual hose diam... but paying $40 for a $5 item runs against my New England ethos.

    Also, for a $5 housing, generally customs overlooks the items, so no fees.

  10. #110
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    Quote Originally Posted by raubritter View Post
    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.
    I have an 88C switch installed in my radiator...the temp switch I got for the flow-thru housing was something like 115C I think...All of the stuff I got for my backup system is buried in a box in my garage (SPAL fan, flow-thru housing, temp sensor, relay, etc). I look for the part numbers and stuff later this week. 115C is when our cars start to get upset, and by about 120C you'll be in the red zone and starting to potentially cause damage. Remember, the aux fan sensor/switch in the radiator activates when it sees the given temp (88C on my car)...so the temp sensor/switch in the flow through housing needs to be above that, but below the 115C danger zone.

    Quote Originally Posted by BimmerBreaker View Post
    It's like a page from my biography or something...
    Emeritus Professor Danomite, at your service!

    Quote Originally Posted by deni2s View Post
    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.)

    First of all: To anyone considering a SPAL fan, do not get this straight blade fan! Get the curved blade design (Model # 30102049)...it's WAY quieter, and flows over 25% more air! If you run the system like this, you will be using the SPAL fan as your main fan...since the 185F (85C) will trigger before the sensor/switch for the aux fan. Our cars came with a 99C (210F), and the optional lower temp 88C (190F) switch is still higher than that 185F switch. If you do want to run the SPAL fan as the main fan, I'd recommend a 195F switch/relay, a PWM module (Derale makes a decent one, and the stock 99C (210F) aux fan sensor/switch in the radiator. Other wise you'll be running your fan only at 100% duty, and the hard on/off triggering will certainly shorten the lifespan of the fan.

    You don't need to re-thread anything. They make temp sensors/switches with the correct thread pitch, and adapters for specific sensors/switches.

    Quote Originally Posted by cleanerPA View Post
    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.
    Stop trying to back-paddle now. We weren't talking about that before...we were talking about the viscous fan exploding and causing damage, hence the suggestions to remove it all together. As for having nothing else there, there is something else there...it's called the aux fan!

    Quote Originally Posted by BimmerBreaker View Post
    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...
    ^^^ All of this x 1,000,000!!! But I'm sure cleanerPA will tell you that that's just fake news, and has never been proven. Oh look, here's the retort below...

    Quote Originally Posted by cleanerPA View Post
    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.
    You're killing me with your #whataboutism. Also, the electric fan doesn't destroy your radiator and shroud, cut through your hood, or chop-suey your hoses.

    Quote Originally Posted by gmushial View Post
    Not sure why one would want to try to rethread the temp sensor - why not just find one that fits; or conversely, have a sensor and find an housing that fits it? ...
    Correct. Find a housing with the proper threading, or just buy an adapter...some of the housings even include an adapter!

    Quote Originally Posted by gmushial View Post
    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.
    Yes, yes, yes!!! But...ORANGE Martians do work on Tuesdays, so you could still get abducted by them on a Tuesday afternoon. *I'm pretending to be cleanerPA.

    Quote Originally Posted by gmushial View Post
    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] ??
    The housing will fit in the hose fine. I'll try to dig up the info on the parts I got for my backup fan mod. You will only need a PWM system if you're using the SPAL fan as the main fan. The PWM module slowly ramps up the fan as needed to provide cooling, and prevents continuous, harsh on/off starts of the SPAL fan motor. If you're going to use the SPAL as the backup, then you just need a temp sensor/switch higher than the one in your radiator (probably 99C/210F), but lower than the 'danger zone' temp (115C/239F). If you solve for problem "A", then problem "B" is included.

    Quote Originally Posted by rasmuw View Post
    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?
    NO, NO, NO!!! 80C is WAAAAYYYYY too low!!! Your fan would be on practically all of the time, unless you were always moving! See my answer above for the temp range you need.

    Also, we DO know EXACTLY how hot our engines are running! I run a bluetooth OBD2 module that shows me real-time actual temp of the coolant in the head...that's how I know if and how well my cooling system is working! If you're considering a backup fan mod set-up, but don't have one of these bluetooth OBD senders yet, then invest in the OBD sender FIRST! Get some baseline data, then you'll know if/how your mods are working.

    I don't know of any aux fans failing personally, but I do know of plenty (over 15) viscous/mechanical fans failing. Getting rid of that thing is the best thing you can do for your hood, radiator, hoses, etc.
    Last edited by danomite; 12-12-2017 at 01:06 AM.

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  11. #111
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    Many thanks for the feedback :-)

    Though question: is the radiator switch really 99C? I thought it was an 80-something number? Or is that the lower trigger temp? and 99 is the upper?

  12. #112
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    Quote Originally Posted by danomite View Post
    NO, NO, NO!!! 80C is WAAAAYYYYY too low!!! Your fan would be on practically all of the time, unless you were always moving! See my answer above for the temp range you need.

    Also, we DO know EXACTLY how hot our engines are running! I run a bluetooth OBD2 module that shows me real-time actual temp of the coolant in the head...that's how I know if and how well my cooling system is working! If you're considering a backup fan mod set-up, but don't have one of these bluetooth OBD senders yet, then invest in the OBD sender FIRST! Get some baseline data, then you'll know if/how your mods are working.
    Thanks for the correction. If I were to get a bluetooth OBD2 sender for an iPhone, what would you suggest?
    Wayne

    1998 M Roadster
    1994 Honda ST1100--sold

  13. #113
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    Quote Originally Posted by gmushial View Post
    Many thanks for the feedback :-)

    Though question: is the radiator switch really 99C? I thought it was an 80-something number? Or is that the lower trigger temp? and 99 is the upper?
    The temp switches on our cars are two-stage switches...they have a low-speed and a high-speed trigger. The standard switch, as installed at the factory, is a 90/99C switch. The lower temp 80/88C switch came on the smaller 4-cyl motors in the e36's and Z3 1.9. You will have to modify the switch slightly to get the plug on the connector to fit. It took me 5 secs with an exacto knife to remove the small plastic tab so that the connectors fit together.

    BMW part #: 61 31 8 376 440

    Quote Originally Posted by rasmuw View Post
    Thanks for the correction. If I were to get a bluetooth OBD2 sender for an iPhone, what would you suggest?
    There are hundreds out there...they all basically do the same thing: allow line of communication from your DME to your phone/tablet/etc via bluetooth. I bought mine on ebay for about $10. You will also need to download and install an engine monitoring app as well...I use the Torque app, but there are several different good ones out there.

    Good luck!

    "You don't win silver....you lose gold."

  14. #114
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    seems if someone made a plug and play kit for a high end puller fan (are there better options than Spal??) for our cars there's plenty of interested owners... the above assembly of parts looks promising...


    as the SME's have noted, you need a shroud for a puller if you are serious about effectively moving air. Years ago i built one for a rod out of a large deep dish pizza pan or hot water heater basin (don't remember which, they are similar). bolted right into the existing (overly large) shroud and the spal tucked straight in. very effective

  15. #115
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    The problem with the cheap ebay flow-through housings is that they are threaded for 1/8 inch fittings, which might be ok for a gauge sending unit, but all the thermal coolant switches I've found are at least 3/8 inch. So it seems if you get the ebay one you'll have to make the hole bigger and re-thread it. Or go with the more expensive ones.

    Also, the best I could find for a thermal switch is this:

    Be Cool 75099 (on= 210F/ 98.9C, off= 190F/ 87.8C)

    But it is basically equivalent to the high side of my stock switch (99C). I couldn't find anything with a higher trigger temperature. (I did find a 235F/ 112.8C switch to trigger a warning light, but it's just an on/off switch, no over run. I don't think that would be good at all for running a fan in an overheat situation).

    Anyone have any ideas for a non-adjustable switch (I'd rather avoid more possible failure points with electronic adjustable switches)?

    I suppose I could change to a 80C/88C on the upper switch and then use a 99/91C switch on the lower one, but would rather not. From what I've read it will be 'fighting' with the stock thermostat if you do that. Unless someone can explain how it works well with the stock thermostat temperatures?

  16. #116
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    I have written many long posts, indeed a complete thread, describing the theory and practical operation of our cooling systems. No, it will not be fighting the thermostat.


    This thread has taken a weird direction. It is focusing on no load minimal heat generation conditions. This area is not a problem. The aux fan is more than adequate for even desert traffic conditions, as stated here. My last years of development work wasn't about idle conditions, it was and eventually will be about higher loads highway speed cooling. The S52 sucks in this area. Stacking more fans in the air stream will just make this worse. The only thing I have with idle speed conditions is I'm convinced BMW put the fan switch in the wrong place, high on the tank when the draw is at the bottom. I suspect that corner of the radiator has stagnant flow at low flows of idle, and this is exasperated by the lower idle flow of the much loved Stewart pump.

  17. #117
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    Sorry if I'm misunderstanding you, but what I was talking about is a situation where either the aux fan or the stock radiator switch has failed, and we are trying to make a backup for that possibility with another temp switch in the lower radiator hose that triggers a spal fan only in that case to prevent overheating.

    Maybe it's overkill, but in my case I already have installed the spal fan so I might as well make it a real backup (currently it's just wired to the same temperature switch as the aux fan, and it seems the temp switch is a more likely failure point anyway).

  18. #118
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    OK, let me see if I've got this straight...

    The main fan can be removed from behind the radiator because the car shouldn't overheat anyway (and there is a separate auxilliary fan that comes on only with the increased load of running the AC) and as it is, it risks causing major damage when failure occurs.

    Those that advocate adding a SPAL electrical fan do so because they don't trust the car to stay cool when the main fan is removed, or they just want the added comfort of having a fan there.

    Am I right?

  19. #119
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    For me personally, the reasoning is this: the cooling system was designed with the mechanical fan, and they added an electric fan to augment it for AC use or whatever. Yes, it turns out the aux fan works fine as a main fan. But it wasn't designed to do that, so could the extra workload/stress cause the aux fan to wear out prematurely or fail? I don't know. But as Randy and others have said, aux fan failures are very rare. So odds are you could just delete the mechanical fan and let the aux fan keep things cool and not have a problem.

    I did this 5 years ago, and at the time the spal backup seemed like a good idea. If I were doing it now, maybe I wouldn't bother. Then again, I live in Texas so a backup seems like a pretty good idea in the intense heat...

    So long story short, for me, the spal is just a backup in case the aux fan fails (very unlikely) or the temp switch fails (less unlikely). I'm sure everyone has their own reason.

    Edit: Then there are the relays for the aux fan. I've never had an electrical problem with my Z3, but relays can eventually fail. As an example, I was recently driving a big Ford rental van on a long trip. At the destination the blower motor for the AC/heat in the front stopped working. The one in the rear of the van (for passengers) continued to work. I checked the fuse, it was ok. I switched the relays for the front and rear blower motors, and then the front blower worked again... But so did the rear. So no fuses or relays were even bad, just a bad connection. And those relays aren't even in the engine compartment, but in the passenger compartment in a much more comfortable environment.

    Again, I haven't had any problems like that with the Z3 (and hopefully never will), but it's just another thing that could happen. With a spal fan on its own circuit with its own relay and temperature switch, you have a good chance of saving your engine if something were to fail with the aux fan or associated relays and radiator temp switch. Yes, it cost $150 or so (more when you count the flow-through connector and temp switch) but that's a lot cheaper than a new engine. Anyway I spent more than that on a Mason clutch pedal....
    Last edited by raubritter; 12-13-2017 at 01:22 PM.

  20. #120
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    Quote Originally Posted by raubritter View Post
    ... the aux fan works fine as a main fan. But it wasn't designed to do that...
    An electric fan is my only fan. The main fan, not auxiliary.
    It was designed as the main fan for my Z3 which was built in 10/96.
    It never comes on for overheating except after a few minutes at hot summer stop lights. It cycles on when the temp rises from the normal 207F to 212F.
    I am glad that I don't have a troublesome and unneeded mechanical fan.
    BMW MOA 696, BMW CCA 1405

  21. #121
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    I'm all for electric fans. And deleting the mechanical fan on the Z3 is a given for me... My Mini also only has an electric fan (it also has no coolant temperature gauge... I don't like that very much). However it was designed for that fan to be the only one in the system (like your Z3). Like I said, it's probably overkill to have a backup fan on a 6-cylinder Z3... But then again...

  22. #122
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    Quote Originally Posted by raubritter View Post
    The problem with the cheap ebay flow-through housings is that they are threaded for 1/8 inch fittings, which might be ok for a gauge sending unit, but all the thermal coolant switches I've found are at least 3/8 inch. So it seems if you get the ebay one you'll have to make the hole bigger and re-thread it. Or go with the more expensive ones.

    Also, the best I could find for a thermal switch is this:

    Be Cool 75099 (on= 210F/ 98.9C, off= 190F/ 87.8C)

    But it is basically equivalent to the high side of my stock switch (99C). I couldn't find anything with a higher trigger temperature. (I did find a 235F/ 112.8C switch to trigger a warning light, but it's just an on/off switch, no over run. I don't think that would be good at all for running a fan in an overheat situation).

    Anyone have any ideas for a non-adjustable switch (I'd rather avoid more possible failure points with electronic adjustable switches)?

    I suppose I could change to a 80C/88C on the upper switch and then use a 99/91C switch on the lower one, but would rather not. From what I've read it will be 'fighting' with the stock thermostat if you do that. Unless someone can explain how it works well with the stock thermostat temperatures?
    I see them threaded for a variety of sensors - 1/8" thru 11mm... but beyond that, if push came to shove, one could always drill out a smaller one and tap it for a larger size - so I don't see that as a problem: though I fully expect to be able to buy one of the correct hose diameter and sensor diameter, off the shelf, no problem.

    W/re going to the 4-cyl switch... my understanding is that the purpose of the radiator is to provide the cooling system a source of cooler water to blend into the mix within the engine, so having a lower temp switch means that: a) the aux fan runs more, but b) the cooling system management blends less 90C water into the mix, than it would 98C water from the radiator.. but will defer to Randy.

  23. #123
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    Quote Originally Posted by cngizbleevng View Post
    OK, let me see if I've got this straight...

    The main fan can be removed from behind the radiator because the car shouldn't overheat anyway (and there is a separate auxilliary fan that comes on only with the increased load of running the AC) and as it is, it risks causing major damage when failure occurs.

    Those that advocate adding a SPAL electrical fan do so because they don't trust the car to stay cool when the main fan is removed, or they just want the added comfort of having a fan there.

    Am I right?
    No, or at least in my case... I'm happy (plus or minus) without the mechanical fan and with just the aux fan... but given the temps I drive in for months at a time, would like a backup, whereby, if the aux fan dies (or the sensor, or any part of its system) [have had one go on another car - mostly due to the 1/2 mi of dirt road leading here, and the amount of dust things mechanical end up sucking up]: I would like a backup system in place that will take me through the week (mindlessly) and allow me to replace the aux fan at my convenience... would also like an idiot light (LED) that comes on when the backup is being used, as a warning that something is amiss... so at least in my case: I'd like to spend money on a system that doesn't get used; but if it does, it let's me know it is being used, and allows me to continue to do what I was doing without concern [4000mi geology field trip to the desert SW etc].
    Last edited by gmushial; 12-13-2017 at 02:17 PM.

  24. #124
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    E36/7 E36/8x2 E39/2 E46
    It has been noted that the economy and hem lines seem to be related. Imagine if the government attempted to control the economy by strictly regulating hem lines. Ludicrous, but the same thing is done every day with cooling systems. The coolant temp is just that, the temp of the coolant. It is NOT the engine temp. Yet everyone seems to try and pin immediate engine failure on a specific coolant temp.

    Want an example? Look at the guys running Evans. They brag about the lower system pressure and look at the coolant temp gauge as verification that it works. In fact, propylene glycol has such a piss poor thermal transfer rate that while the coolant is the correct temp (themerstat controlled), the actual engine temp is easily 100F. The engine doesn't fail because the coolant doesn't boil off. We won't talk about the performance hit.

    AS LONG AS THE ENGINE IS FULL OF LIQUID COOLANT, THINGS ARE FINE. The failure comes very quickly when the liquid goes away; either by leakage or steam generation.
    The temp gauge and the red light are not there to protect the engine directly. They are there to protect the coolant. Because as soon as you boil the coolant, the engine is in jeopardy. .

    I have a lot more to say, but I'm too damn tired. Chemo does that to you. If you are worried about boil-over, to borrow a Model A term, the two best things to do are to run the coolant at the correct level and to make sure you have a working 2.0 bar pressure cap. The 2.0 cap is there not to set the system pressure, but to protect against premature boil-over if things do go wrong.

    As far as how to do a temp sensor, I dunno. My comment long ago about if I was to do a Spal was based on my system and the spal being stand-alone. I would have the sensor bung welded into the radiator tank right at the lower outlet. Your sensor can go anywhere from the lower radiator outlet to the thermostat.


    /.randy

  25. #125
    Join Date
    Aug 2006
    Location
    Texas
    Posts
    462
    My Cars
    '02 Z3, '09 Mini
    Damn... Sorry to hear that, Randy. I hope you kick its ass soon.

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