Here's a thread: https://r.tapatalk.com/shareLink?url...9&share_type=t
Hope that works.
Note the range from center mark to first tick after is 20 deg F (from 190 F at center to 210 at first tick). That's AFTER removing the buffer. Hence built in buffer is something greater than 20 deg F.
Maybe the buffer is 170-230F. Whatever it is, it’s broad enough that your car is either too cold or at risk of overheating if the needle is moving. I think you can watch on the obc by unlocking it and entering a certain code. I have another gauge in my car but maybe the sender is not accurate.
Wow that's alot of new info. Didn't know that the temp actually went all the way to the red before coming back to centre. Guys, would you know the exact temp that is supposed to be engine optemp? Ignoring all buffers etc, what is operating temperature exactly ?
so the temp sensor that is located on the head of the m52 is for the dme right? which sensor is for the gauge on your dash then
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ok guys lets just say we dont want our cars temp gauge to be in the red or even past the middle, soon as i see the gauge creep past the middle i turn the engine off, even if im rolling down the road i push clutch in, key out and come to a safe stopping place. id rather be stranded then wrap the cylinder head, usually when you exceed 225f the gauge will start to move past middle, and when you are at 250f its in the red. sadly i cant test my electric fan since my fuel pump died . was thinking of taking the aux switch out and putting it in a bucket of water of 220f to see if relay activates.
You should stop the engine if its in the red or threatening to get there, but before that its a matter of concern but there is no need to go all emergency on it. I would only go emergency mode if it hits 3/4 and I don't know why.
That cylinder head and block is strong. Many people who come onto the forums - we get a warped view of the probabilities. I mean like only people with problems will make posts here. After awhile you will naturally think the car is full of problems. Yet as a percentage of the total E36s on the road it might not be significant at all. Those cases where someone just touches red and the head goes - doesn't square with reality. UI've overheated my M50 several times before with no problems, and this is with an alloy head but cast iron block - higher risk of cracks due to differential expansion. Not the problem with the M52/54 as I understand it.
I'm sure touching head and all hell breaks loose does happens but it would be very obscure. And remember we don't know the detailed history of the car in question - all that would be highly relevant imo.
An abundance of caution never hurt anybody. My comments here are not a judgement on that.
And you don't need the fuel pump to test the aux fan. It is purely electrical. Just put the key into position 2, then pull the connector from the radiator's double temp switch, and jump the internal sockets. You should hear the fan running at low and high speed. The double temp switch can be tested by checking continuity when you put it in hot water. Or you can create a run hot situation temporarily on the car. At just past middle, definitely by the time its between middle and 3/4 the high speed aux fan comes on. Then as it runs and cools the radiator down, it will switch to low speed, and then it will shut off.
the head is strong yes but unless you have the m50 which is cast iron head, all m52 and 54s have aluminum heads so i assume the aluminum is going to crack or wrap eventually even after being 20 yrs old. you also lose bit of compression by overheating it. so when it happens to me i find the next exit and shut it immediatly
The m50 has an iron block. The head is aluminium. Actually all the heads and blocks (for the m52/54) is not aluminium, but an alloy that is far stronger than aluminium which is a very soft metal. And the main thing that causes warps and craps are differential expansion - two different metals connected to each other firmly, expanding at different rates and thus creating a fissure at their joint. The likelihood of this is lower when the block and head are made of the same material. And my M50 have survived numerous overheats without lasting issue.
Expansion of the metal under heat - this expansion is not huge, because the temperature increase is not substantial when compared to the melting point of the metal concerned.
Anyway this is an academic argument. Once your gauge crosses 3/4 you need to give yourself a good reason why you shouldn't pull over. And if you can't then pull over and check under the hood. But you don't need to break out in a cold sweat even if it hits red - that's my point. But it is exceedingly irritating.
OK, here is my experience. The car is my DD, has AC, and was in Dallas and now in Austin, so dealing with a pretty good heat load / AC load + aux fan / traffic and low air flow. I do not have an oil cooler or a vented hood (yet).
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My aux fan started failing and blowing fuses, so I replaced it.
The new fan had smaller connector pins than the original, so it would lose its connection sometimes. Maybe a lot, but I'd only notice it under certain conditions. Because my mechanical fan clutch was dead and it took me years to realize - the aux fan was picking up the slack.
I finally put all the pieces together, fixed the pins on the aux fan, installed a Mishimoto radiator, and replaced the mechanical fan with a 17" fully caged Derale fan that I interfaced with the factory shroud and wired into the low temp wire of the the aux fan switch (this switch is the only piece of this whole equation that is still original).
Others have commented on the difference between the fan switch and the vehicle's temp sensor.
These are my OBSERVED temps for various conditions using an OBD bluetooth transmitter and the Torque app (i.e. temps come from the Torque app).
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The needle hits 12 o'clock around 170-175 degrees F, and starts moving north again about 225 F.
I forget where the upper line is - I want to say 250, and the red starts at 265, but I've only ever seen the upper line in my own car once, and have never gotten to the red.
But these numbers would be in line with the boiling point of 50/50 water/coolant at 16-20 psi, which is when you catastrophically lose cooling capability, so it makes sense the OEM would put those marks there.
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As for the aux fan switch.
Low comes on around 208 degrees. You'll never see high with your hood up and the low speed functioning (even without any other fan running), so I don't have a recorded number for the high speed fan.
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I will also note that my fan (and I think most fans) run on low speed with one wire hot, and run on high with two wires hot. Meaning, you wire the low speed to the low temp switch and the high speed to the high temp switch. The low temp switch remains hot when the high speed switch closes. If you don't have two switches and want your fan to run at high speed, you wire both together into the one switch for high.
Being in Texas, I don't see any need to ever run just at the low speed, so I wired both together for high speed to come on from the low speed aux switch.
So the Aux fan comes on at low speed when it hits 208 or when the AC is on. It ramps to high when it gets to whatever the high temp is.
My primary electric fan comes on at high when it hits 208 or when the AC is on.
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Even at crazy high ambient in the summer (120 or so), my car will run as low as 190 degrees sitting in traffic with the AC on. It can get up to 220 at sustained high speeds in 120+ weather, but will drop quickly to 200 or lower when I get off the highway.
And being wired into the AC, my fans almost never come on from temperature. If it's cool enough to NOT need the AC, it's cool enough the car never gets up to 208 just from sitting in traffic.
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OP, if you still live in Dallas, you need to wire your fan into the low speed switch.
The problem with using the high speed switch is that you're already above the boiling point of un-pressurized coolant. The more time you spend in the higher temperatures, the more time you spend with higher pressure in your system, causing fatigue, and the more opportunity for failures.
And the faster a failure spirals out of control.
This is why things go catastrophic. To address the conversation just above here, a healthy cooling system can handle up to around 265-275 depending on coolant mix and radiator cap (50/50 mix at 20 psi won't boil until 275, discounting any localized hot spots). With an old / unhealthy system, you're rolling the dice above 225. Any single component (a hose, fitting, plastic radiator neck, expansion tank) can be the failure point and get you in hot water quickly - even if most everything else is new.
Once the needle starts moving (passing 225+), if you were to lose pressure your coolant is already above its boiling point. Pressure loss results in the coolant immediately boiling. So the coolant in the engine becomes steam, which means the only thing cooling your engine at that point is the oil. And that's why the temperature jumps up so quickly at that point.
If it was me (and it was), I'd start as low as possible and keep it as low as possible.
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
Thank you
Reference blckstrm's response for thoroughly explaining what to do in your situation. Your wiring is a little off, redo and test to check function as you should be wired to the low speed not the high speed. If nothing changes and the fan isn't kicking on then it could simply be a defective part from the manufacturer.
Also, I would recommend putting the electric Spal fan behind the radiator as a puller-style not a pusher. You can retain the factory fan shroud which is helpful.
For about 20 years, I have been using Evans coolant and zero pressure or lower pressure caps in some of my cars. I like the idea of less stress on the heater core, which is a pain to change. It has pros and cons and is not for everyone. Boiling point is much higher than even 50/50 water antifreeze and a 29 psi cap. Supporting mods probably a good idea — wider core radiator like z3 s54 m or mishimoto version or zionsville plus heavy duty pump like Stewart.
Also, you should have wired a fuse in line somewhere. My fan is getting old and blew the fuse today (I may have a replacement in my near future). Make sure you check that fuse before going crazy.
But yeah, it won't be turning at 208 if it's on the high temp. But that's an easy, easy fix to switch it to the low temp wire.
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
ye I’m still in Dallas area, will you come back to the area or are staying Austin, wanted to see your build.
I did Add 30a Fuse, gonna switch it to the green and black wire(low temp switch) and if that doesent work, will have to get the 318i switch. But I will have to test all this after I can get the e36 started cuz now it won’t even fire up, fuel pressure is good at 51psi, gonna check for spark later, bad thing is there no crank sensor code so kinda stumped, oh well gonna try getting it back on the road
Last edited by zohaibrose; 02-08-2019 at 07:11 PM.
I'll be at the big SCCA race at COTA tomorrow if you have the day free and want to watch the races. But yeah, I don't make it up to Dallas hardly at all anymore, and even when I do it's with the family in the Escalade, not in the M3.
I was going to say you're safe for a couple days without a fan - it's almost cold this weekend. Did the wiring issues run the battery down?
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
The oem system was simple and worked
Idk why there is so much problems with the electric fans. Buy the right stuff and do it once. I'm using the mishi fan, + mishi temp controller /relay. Literally no splicing, all plug and play. Turns on at temp set on controller, turns off below, no physical switch nonsense.
well i wired to the low temp n still not come on at 208f , i even attatched a ring terminal to the grey wire and tried grounding it but the fan didnt come on with key in position 1. someone here said if you ground that grey wire from the spal relay n the fan doesent spin then your wiring is incorrect,
but i dont get it, i have 12v to the wire going to battery jumper terminal, hooked up orange wire to pin 16 of diagnostic port, red is hooked up to the fan harness, and grey was tapped into the green n black wire. i can get the fan to be on constant if i remove the relay and apply power and ground to it but the relay seems to not work. i even tried removing the orange wire to see if the fan would turn on constantly without igniton but still no go, thinking my relay no good. darn i really need the engine to be kept cool or i will be stuck with a scrap engine. WHAT DO I DO
Recheck your wiring. Make sure the relay powers the fan when the relay is triggered, by testing the trigger— the wire that taps into the temperature sender. It supplies a ground that turns the relay on. There is only a ground when the wax in the sender melts and allows contact between the wire in and the wire out. For the test, forget about that. Just run a lead off the relay ground, which is 85 or 86, depending on how you wired (one is switched relay power — key on #2 — if you want switched fan operation or unswitched if you want the fan to run with the ignition off, and the other is relay ground but these two terminals can be swapped without affecting relay operation). These two wires are small gauge like 14-18 since they pass little current.9
30 is heavy gauge power in and 87 (not 87a) is heavy gauge power out to the fan. The fan ground is to the car chassis.
Beware of using bmw colored relays. Many are not wired internally like Bosch standard relays. Unless you know how they work, use a relay with 85, 86, 87 and 30 terminals. It’s ok if there is an 87a in the middle but don’t use 87a.
Last edited by pbonsalb; 02-13-2019 at 11:05 AM.
Wouldn't it be great to just have the stock system working perfectly, life could be so easy
For most people, stock is easiest and more than adequate. However, none of my 3 cars are stock. I enjoy them much more in modified form.
I salvaged a fan motor harness end and spliced it in. Fits perfectly. At least I think that is the connector I salvaged that fits. This was over 5 years ago.
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